I am from a past position at Delco Advanced Development and Reliability Engineering , as the US ADRE facilities engineering coordinator. I am very impressed with your attention to calibration and following a predetermined process to create a controlled sequence that is to be followed in the testing of the product and use of in a different perspective than we usually see online
I wonder what the temperature was when he was doing this. I always strongly caution people about using machine shops that are 90 to 95° F inside during the summer and 50° F inside with everyone huddled around a kerosene heater during the Winter, I've demonstrated to people how much dimensions change over just a 15° F from what's considered the temperature that machine work is supposed to be done at which is 70° F, it makes a bigger difference than people think, especially if you're sizing aluminum pistons into an iron block or iron motorcycle cylinders, when you get down to a minimum clearance like .00075 inch that I sometimes deal with it makes a difference, a BIG difference.
13 years of building race motors and some classes have stock rod rules, there was never a question about resizing the big end when changing the bolts. The more power you plan to make the more prefect things need to be.
I'm 71 years old and rebuilding a 56 Chevy with a 1969 Corvette 427 that has sat for over 25 years from the last time I built it. Had a new cam part part failure, long story and nothing to do with the build process. Life got in the way, raised 2 fine sons, and am now starting over. Your attention to detail makes me question my sanity! ;) Thinking maybe I should just pay a machine shop to build the long block for me! I just really want to drive it again before I die! :)
Many many people just love the building process and not the using part. I've known so many amateur boat builders that spent a decade or so building a boat only to sell it within six months of launching, only to realise that they loved building the thing more than they did using the thing.
It's easy to just pay a machine shop to assemble an engine. The problem is finding a machine shop that'll actually care half as much as you do. And when you do it's gonna cost time is money and the majority of machine shops would rather pump out work for local repair shops who aren't so picky. When you do all the measurements yourself you are 100% sure it's correct.... assuming you spent the time doing it correctly. It's not difficult but there's some cost if you didn't already have the tools.
@@garysgarage.2841 Fortunately, there is a machine shop close by that has a good name, and he races too! He's my age, but he has the experience and the tools. I think I will be money ahead, at this point in my life, to pay a professional to build the short block, and I can finish it. :)
BTW, awesome video. An engineer that actually knows how to turn a wrench - there are so few of us. I work with some engineers who don't know what a ratchet wrench is. Subscribing!
@@tempest411 Yes possibly....in the English speaking world this confusion is common in people who use the term “engineer” when they are do not have the prerequisite training from a tertiary education provider. It is exacerbated by the fact that the media do not understand the difference and most people will never need to deal with an engineer in their daily lives so public exposure to engineers is limited. It is almost exclusively an issue in English speaking countries.
You've either got measurements or you've got an opinion - great perspective to take and I really appreciate the time taken to make this video - thank you!
Based on some of the comments (thanks) I realized I should have included the fact that when I reinstalled the stock rod bolts (while forgetting which one was from which side), and re-torqued to factory specs, the rod measurements came back as P1: 2.2392" and P2: 2.2394", so within .0001" of the initial measurements, and a complete A-B-A test. The dimensional changes were definitely due to the higher clamping force from the ARP bolts, and not cap alignment, press fit, etc. And for those suggesting just using the same stock torque with the ARP bolts, that negates the advantage of the improved bolts. You need the greater clamping force to hold the rod together at the higher RPM loads.
I would have liked to see either a new stock bolt and check the OOR or a stock bolt stretch measurement. I think ARP puts priority on fully loading their fasteners to the ideal yield point. Which ends up being a lot more clamping force than you want. I bought some arp bolts for my stock gen 4 but returned them for exactly this reason. Here’s the interesting part I think arp has some bolts that are designed to not require machining. Or at least I have read that somewhere for the cracked ls rod caps. Unsure Cool video appreciate the thoughtful and thorough job you did, dropped a sub. Would be cool to see if you came back to this with a few different alternative approaches/comparisons. Maybe try to find the rod bolt stretch needed to keep the rod round, and compare stretch of new and old bolts vs ARP. You could beat a center punch into the stockers to give yourself a nice stretch measurement point. As long as you use the same mark you should be all good
But even if ARP Bolt torqued to the same spec as a stock bolt... ARP still going to be stronger and hold more... it's not going to break at the same yield as the stock bolt just because you torque them at the same... right
wouldn't the higher clamping force simply be a result of the higher torque, not the bolt material? Couldn't you get the same benefits of the ARP bolts higher tensile strength by just torquing them to the factory torque spec and likely not have this issue? the ARP torque spec is 25-30% higher, so it stands to reason that it would create more distortion. Is there any benefit at all for using the higher torque requirement?
@@funkyzero No, the amount of stretch comes into play, ARP bolts have different qualities than stock bolts do, they react differently under the same amount of torque and also react differently when the rod heats up and things swell.
Not only bearing clearance but bearing crush! I applaud your diligence for precision but a few pointers. If you measure the rod in 3 places you can determine if the cap is misaligned now or merely distorted. Number 2 measurement alone won't give you that imfo. Couple other points; ALL measuring equipment should be close to 70 degrees and the subject your measuring also. Very difficult to use the mic to set the bore gauge in tenth of thousands. The finger pressure alone can throw the bore gauge off even tho your rocking it. A setting fixture is preferred. And yes any change in torque will 99% of the time change a bores dimensions. This goes for guys putting studs in main caps, one can get by without line honing if you use the exact same torque on stud as main cap bolt had! Good Video!!!
It's because of the increased torque on the bolts that it changed. If you changed the bolt but still torqued to factory spec you see very little change. It still is a yes and no for a resize. If you plan on changing the amount of torque on the bolts then you need a resize. Main bearings do the exact same thing when you change the torque of the bolt. It can also change when a bolt is slightly longer or shorter or a stud is used on mains.
I love this! Definitely worth subscribing for....wayyyy back in high school I built a Pontiac 400 for my 2nd gen Firebird, I built it poorly of course but the advice I got from my shop teacher didn't help. I wanted to put better rod bolts in and he was all like "go for it". 3 months into running that engine the bearings were finished, this wasn't the only factor of course but it obviously helped. I was told after that about resizing rods, I was a dumb high school kid who got all his knowledge from magazines so how would I have known? Watching this brought that all back, and I love the full hardcore geeky confirmation aspect. Just awesome!
Great video Ed, I've gone through this same exercise a few times while building engines. Some rods don't move around nearly as much as others, my general rule of thumb is that you should always check/measure if your replacing rod bolts.
I suggest measuring in both diagonal directions to understand the variation in cap shift left to right. Obviously the ARP bolts/lube/torque do influence clearances shown in dimension #1. Appreciate the testing!
Good Video. Fortunately for me unlucky for a buddy of mine I was taught this lesson a long time ago. You always check the big end of the rod. I have seen rods that did not change, I have seen seven that did not change but one did. Most of the time all eight need resized. The little Ford rod will take tons of abuse without failing, the block splits first.
Depending on the head of the rod bolt, some rod bolts sit flatter than others. I suspect that can give the connecting cap a bit of twist/torque and distort the end.
yes sir!! Hard to beleive those Little rods hold up....but they do,but like you said the block!!!! Worked in a machine shop 25 year ago doing the rods/pistons/ and balancing.seen some 289/302 and 283/327 with them spinning 7,000 on stock stuff.......but re-sized or bore checking is the key along with oiling! Sounds like you have seen some 302,s pushed to the limit!
Yeah dopey office workers with their breakfast cereal pack commerce degrees always mistake data for information. They then apply a good dose of confirmation bias and voila get the answer they want. When it inevitably turns to crap - time then to initiate a blame loop with the lowest paid workers the scapegoats for their incompetence. The world is full of great hoards of these scabs. W. Edwards Deming would roll in his grave if he could see how his comment was perverted. I know how it all works ... BTW I prefer, The trouble with life is all the stupid people have an answer for everything and the intelligent people can't make their minds up. At least that way it's keeping it real. Data is not information and is the realm of the stupid.
@@The_Performance_Laboratory Where the hell did you get that spec book at 3:42? I've been looking for one of those for a couple of years, it has specs for the SVO right? I would guess so if it contains the XR4TI specs. Any info would be appreciated, thanks.
Great video! I didn't know there were people out there swapping rod bolts that were NOT resizing their rods. I can imagine those doing that talking trash about the bolts they put in after they spun a bearing.
Great video to show how to measure a rod first, Secondly thank you for putting this myth to sleep about if the big end needs to be resized with ARP rod bolts. Keep doing these types of videos so I can geek out with engine-building content!!!!
Going from 23 lb-ft with oil lube, to 35 lb-ft with UltraTorque is a significant change in bolt tension. It is no surprise the big end changed shape, getting wider and shorter. But now the width of the big end is above Ford's max spec so this rod cannot be resized to spec. If the new bolts were installed to Ford specs, much of the benefit of the stronger bolt is lost, but it is still an improvement. My solution here would be to use =0.001 bearings and go with it.
Interesting video. I come from the world of BMW E46 m3s, high strung motors with tight tolerances. Rod bearings are a 60k serviceable item. Everyone seems to get away with using aftermarket ARP bolts and just torqueing them (no stretch measuring). My engineer brain cries bloody murder every time I hear this, and your findings are exactly why.
It's not in the slightest bit obscure. In fact, it's common knowledge, normal practise, and perfectly logical. It's the exact same reason that you must measure bearing clearances with the bolts torqued to spec.
Hi Ed - Thanks for this excellent video. I'm a mechanical engineer too, and appreciate the attention to detail. I'm about to start the reassembly of a 2110 cc air-cooled VW engine (82mm stroker crank w/90.5 pistons) for my 1970 Crew Cab pick-up. I had this engine together about 10 yrs ago, but paid someone to line-bore and build the shortblock for me because I was doing 60-70hr weeks at work. I built up the rest like a Swiss watch. The engine seized up (on the main thrust bearing) after about 3-4 hrs runtime. A real heartbreaker. By good luck the beautiful new crank was okay after a competent machinist dressed the journal, re-did the line-bore, and set me up with a new properly sized bearing set. Everything's been sitting in enclosed tubs on the shelf ever since, and now I finally have some time to put it back together. The problem is that somewhere along the line I read that ARP bolts are designed to yield ever so slightly when torqued to ARP's recommended level. That being the case, they are not to be re-used. Or so that source said. It seems like a conundrum, because if that's true then when you torque them to measure & re-size the rods, you'd instantly lose everything when you disassemble to install the rods on the crank. You'd be chasing your tail, so to speak. I'd like to get your take (and maybe that of some of the erudite gearhead commentors below) on this matter. Thanks - and you have a new subscriber.
If the bolts don't specifically say they're torque to yield, they're not. Contact ARP to be sure, but sounds like typical internet misinformation. Also, if you're chewing up thrust bearings, check the trans and clutch setup to make sure they're not creating unnecessary thrust.
@@The_Performance_Laboratory Thanks for the reply. I'll call them and ask - easy enough. BTW, I think I know what happened with my thrust bearing. It was seized at its 3 O'clock and 9 O'clock positions, and totally virgin/untouched at 6 O'clock & 12 O'clock. This led me to suspect that the two halves of the VW crankcase weren't fully torqued together when the line bore was done. So, later when it was reassembled the perfectly round bore went football-shaped under full torque, and squeezed the crank at 3 & 9. One other question - any suggestion for where to buy myself a good but reasonably-priced stretch gauge? I see some at Summit that look pretty good. Thanks
Dude thanks for all the time taken for the video! Much appreciated! Hopefully you've saved someone a major headache! I've never seen rods come back drone the shop without having machining marks on them. And I've seen serious damage done from this exact issue causing rod seizure on journal. If you aren't going to do it right then just don't do it at all
Excellent video. This is why I wont spin a wrench anymore, especially with modifications. Theres no end to the time and money that can be spent making something "better "
That was a really interesting video. As a precision machinist (3~5 micron tolerances, manual machining) and a motorcycle tech it isn't something I've come across before, (even though Triumph motorcycles used bolt stretch since 1950's) Maybe because motorcycles are much higher rpm engines and have to use better quality materials? (imports, 12~20,000rpm) One thing I have found, setting bore gauge is much easier on a piece of 'foam rubber' sheet, 1/2" thick or so. Laying micrometer down is way easier than trying to 'balance' things using a micrometer stand You don't need to touch working ends of micrometer or bore gauge so heat from your hands doesn't make things change dimensions (more critical with aluminium as it has such a high expansion rate compared to iron/steel) Ambient temperature is another factor that needs to be taken into account if your working somewhere 'cold' as body heat can change dimensions more than at a slightly higher temp. (std temp used to be 68f, don't know if that has changed now 'everything' is metric?)
@@The_Performance_Laboratory I just watched a 'bore measuring video', almost got it right I looked for the 'Instructable' I did several years ago. Here's link in case your interested www.instructables.com/The-correct-way-to-measure-a-cylinder-bore-and-mea/
Pre watching this I thought you'd say it didn't matter, I was ready to jump on you because you don't know what that rod (motor) went through. But you got it right! Also I reconditioned rods late high school through college & saw differences in manufacture tendencies after capping them whether they were close or way off.
This video brings home to me the importance of having the knowledge and technique necessary to use precision measuring instruments. It ain't no automatic! Three different people could measure a rod and come up with three different measurements.
Sounded like you had some taper too, also you have a sample size of one. Yes if one comes up out of tolerance then your done anyway. However, if it came up in tolerance, I wouldn't say it was good based on one sample.
I guess some on has seen what a run off that equates to .00025 to .003 side to side will do. It's like some dope looking at the feeler gauges and seeing the thinnest gauge and thinking, that's what .005 look like... That nothing at all
To get a real look at the rod end roundness you need a 3 point precision gauge by Sunnen precision gage. If you are measuring Bearing clearance the dial bore gauge is fine.
If your. Talking about a ag 300 sunnen gauge that is a good gauge but any good bore gage is more than capable of checking a rod end. When measuring at .0001 and closer many things need to come into play even at 3 tenths, temperature of parts, are the parting lines burr free, has the shop warmed up or cooled down is there interference in a bolt radius and more. Has any of the measuring instruments been calibrated ever? Not the standard that came with the set either that needs checking also
@@scottmuller1901 No you need a dedicated rod gauge to measure a rod properly such as the 3 point gauge used (and usually bolted to) sunnen rod honing machines. looks like he is using a Mitutoyo standard set. They are very good. That is expectable he just needs to keep his fingers off the metal part. Automotive machining is very specialized and requires specialized equipment and training to do properly. The tolerances are very critical.
@@scottmuller1901 If you are measuring clearances that's fine; But roundness is what that precision gauge is about. Setting that Sunnen gauge up for use requires a centering set-up for use where a dial bore is not set-up that way. Concentricity is the key. Rod bearings are not round they have a crown thickness which you can measure with a ball mic. That is where a dial bore is used. Sunnen also has the Dial Bore Gauge which has an adjustable point tension on it so it will be gentle on the bearing surface. I have used these tools for many years and some of my friends also use them in Sikorsky for Precision Roundness. Roundness is the Key Word here. You are not getting the full picture for roundness and concentricity
@@willy3377 i know exactly what your talking about . Roundness, concentricity. I have been in automotive machining for 30 + years of my life. There are other tools very capable of measuring this. Take a 3500 series cat rod and try to handle that on a rod honing machine mounted 300 gauge. I have a sunnen rod hone i have the gauge and know very well it’s capabilities. It is a very good gauge for what it does but it is a comparator type gauge that needs a ‘standard’ so to speak for size setting. I was also talking about other things than just roundness and concentricity. I was referencing the effects of temp, burs possibly other factors that will change the process. Miss machined non planar parting lines for instance. I always measure the bearing thickness with ball mics. For consistency. I would also not try to outthink the engineers by deviation from the design specifications for the rod bore in attempt to set clearance. That needs to be set with crank size.
When I first seen the video title I was worried you' were going the other way. I once reconditioned a set of BBC rods with stock bolts to with in a couple tenths. Owner later decided to upgrade the rod bolts. He didn't believe me it was going to change the dimensions. I changed the rod bolts using a support block for the purpose then remeasured the big ends. 4 stayed in spec (but with greater use of tolerance) and the other 4 was out of spec. Another time a customer that had work done from a different shop was told to torque his 302 rods to 45 ft/lb. I informed him that the torque should've only been around 30 ft/lb and that all bolts should be replaced due to over stressed. He ended up paying for the new bolts and the original shop installed them but said they didn't need reconditioning. I've no clue as to how they changed the bolts but the big ends were .006 to .007 out of round. He's never been back to that shop.
On the higher hp aftermarket rods when you remove the cap you'll see hollow dowl pins. Those pins locate the cap so when its removed and reinstalled it's always in the same place. On rods like in this video the caps are located by the rod bolts. When the bolts are replaced they have to be resized.
No, they don't have to be resized. Read the pinned comment, where he re-fitted the original bolts and after torquing to the same spec he got the same dimension. It's not the _bolts_ that change the clearance, it's a change in torque which alters the bearing shell crush. In this case he increased the bolt torque by 50% so of course the dimensions changed.
A few years back I rebuilt a BSA A65 engine. I found that the original rods and caps were round enough. I used ARP rod bolts and measured the stretch, just using a standard micrometer. Once together, I checked the torque. It was within a pound-foot of what BSA specified for the rod bolts. The next time I'll do this will be once my Triumph Trident needs a complete rebuild. I have new steel rods and caps for this, and the ARP bolts which came with the rods. No need to resize for this.
agreed but what does that say about tolerance control on the bolt shank? the only way you can get lateral shift is both shanks are under size to a lesser or greater extent.
Me and my buddies have done the backyard mechanic thing and just thrown in ARP Rod bolt in many different engines... Honda engines... Nissan engines and we've never had a problem but we always just did it to stock spec. I'm curious what would happen if you torque it to 23 foot pound. I bet it would be perfect. You're not trying to clamp the rod any tighter. you're just trying to make sure it doesn't give under more load. And I realize that with torque to yield bolts. you're trying to get it to its yield point so that it's optimized but there lies the question what's the end goal. I don't know but put that s*** on a loose engine and you'll be good to go. Lol For the cost of resizing stock rods you can almost buy a shity h-beam.
You definitely need to resize if you change the BOLT TORQUE. You won't need to resize if you add new bolts but use standard torque settings. Of course it's better to grind, hone and resize, but you need to pull the engine to do that.
@@johncoops6897 That's not true at all. Any time you replace rod bolts even if you put the original ones back in you need to resize the rods. In fact any good rebuild requires resizing the rods . Its very unusual to find used rods that check out as good as the ones here. Oh and changing rod bolts with out removing pistons is ridiculous. The internet is full of "Billy bobs" Experts giving out incorrect advice.
Replaced the rod bolts many times in used engines and worked ok. No issues. Guess I was lucky, and many other guys were too. Great information. “If you look for problems, you will find problems; if you look for solutions, you will find solutions.” - Andy Gilbert Check your main bearing clearances with new bolts, or studs. Its always god to know.
@@The_Performance_Laboratory I used arp bolts in stock 350 chevy rods. A mild street engine. Street driven for three years. Just my experience. I know no two examples can compare. My engine had 89,000 on the odometer when I re built it. This was 20 years ago. We checked the cylinder standard bore, replaced the standard pistons with Forged flat tops. From my understanding Forged Piston don't shrink as cast pistons due to heat. So in my application it worked. This was verified thru the machine shop we used for years. That's what I recall. I know technology today supercedes what we used back then. I am new to your channel. The bearings in the old 350 were all to specifications too. I guess I had a Good engine? Thank you for your knowledge. We checked the clearances too. Everything was good.
I have always told people that there is a difference between something working and something working right. An "OK" engine may run and may "feel" good, but an engine done right will usually have slightly better power and last longer in the same application.
The last few years I've been taking 3 measurement; 1) 45 degrees to rod centerline 2) parallel to rod centerline, and 3) 45 degrees to rod centerline, but on the other side of centerline. More than a few times I've seen measurements at 1) and 3) move in opposite directions with both the existing bolts, and after a bolt change. If you are not routinely looking at this data, maybe you should.
A better made after-market Rod will resize closer to Round if not completely Round. Stock Rods can only come close at best. It is what it is, and you can only get it to tolerance. Otherwise, get yourself a set of Pankel's
In the field of calibration (Metrology) the question comes up, what was your temperature? It plays a big part in measuring. Could have the rod gotten bigger as it might have gotten warmer? While torqueing it down, did it get warmer? If you are talking about accuracy what is the accuracy of a click type torquewrench? Usually it is fare to. say it is 3% and a beam bar type is 1%, keep that in mind. You should have open and retorque the rod bot mutile times then take the average for a more accurate decision. You would even be amazed how the numbers would change if you just heat cycled the rod too and then take measurements. It is a good experiment. Try that if you are curious.
If you do the math, you'll find the dimensional changes from temperature changes you're suggesting are insignificant compared to the precision of these measurements. My torque wrench was calibrated (maybe you missed that part), and things were assembled/torqued several times (but edited out for time). With the ARP bolts, they were tightened to stretch, which takes any torque errors out of the equation. As for heat cycling the new bolts, I would be a bit worried about the metallurgy of the bolts (and rods) if that made a significant difference. How much did your measurements change when you checked that, and what was your heat cycle procedure?
@@The_Performance_Laboratory Your 3" long micrometer will change 0.0002 from 59degF-68degF That is not an insignificant change. You total measured big end change in one direction was was 7-8 tenths. .0002 thou is 25% of that...
@@The_Performance_Laboratory I did see that you said your torque wrench was calibrated. I never question that. I was noting that a click type torquewrench is less accurate than a beam bar type. The heat cycle, I was mentioning would be to bring the part up to operation temperature, a few times then measuring after the part relaxed because metal will change shape. What would happen after a few cycles, would it change? I know you could spend hours debating on accuracy and that could be a hole other conversation. What we required was a 4:1 ratio of accuracy of a tool for a specific part depending on what we were measuring per mil spec. or ISO back in the day. What you doing is very interesting; however, I'm not arguing who is right or wrong and I'm not trying to be nay sayer but the average person doesn't even understand tens of a thousand and I admire you for showing people what your doing. Keep up your videos, they are interesting. 👍
Swapped out the rod bolts on my Chevy LSJ as the engine is in an Ariel Atom. 6 years of to the floor road race track abuse and a rod bolt finally let go. I should have gone with better rods and bolts. Nice video.
Don't know how I came across your channel but I've watched a couple videos. Even though some things already aware of, its nice to watch how people do things either the same way or to learn a new way of doing. Plus have to support our local Manitoban's
One important thing about metrology is the temperature the measuring is done at. Iif you're serious, you can buy circular standards, in a range of sizes, which would avoid any possible cosine error if the internal dial gaude was slightly off when in the micrometer.
@@3rweldingandfabrication375 that was the joke, it closed up the gap on the shell bearing from wear :o) instead of removing the shells, swapping them and putting a piece of coke can on the cap to close it all up :D
No no no! You don't have to use _new_ rod bolts. Just drop the pan and wind the stocker bolts up from 23 ft/lb to 35 ft/lb or more. The more crush, the less rattle. Leave the pan off when you test run it, so that if it's still clunking you can quickly drop the cap and install the coke can shim. Always shim at the bottom, so you don't need to drill an oil hole LOL.
@@johncoops6897 lol, I know your joking, but I actually did drop the pan and shim a knocking rod in an old nova once. I had no money, and needed the car to last a few more months. 3 years later when the cam went bad the rod was still fine. it was a 74 nova with a 250 inline six I drove the car under a big tree, pulled the hood off, hooked a come-along up, and lifted the motor just enough to get the pan off without unhooking anything other than motor mounts. used vaseline as assembly lube when I put her back together. drove her easy for a few days, then right back to driving like a dumb kid. then after the cam went bad, pulled the spark plug out of the offending cylinder to relive the pressure from the non functioning exhaust valve, and STILL drove that car around like a race car for 6 more months before I sold it. that motor just wouldn't die. I finally sold it because I was worried all the raw fuel that dead cylinder was pumping into the engine bay would eventually blow me up.
It replaced rod bolts on a 351 that I did a budget rebuild on and had to use a brake cylinder hone to get the proper fit on the crankshaft journals . If l would have had the funds to have a machine shop , I would have done that then spend about 10 hours getting my required bearing clearances . Even though it was a lot of work , I got it running and I have driven it about 35K miles and it still has excellent oil pressure
I expected a change, but, I was surprised at the amount of change in the up/down measurement. I wasn't surprised at the change across the big end. After thinking about it though, the parting surfaces are fairly rough from the factory, so you may get more "crush" of the surface metal than a rod that has a smooth ground surface, like after a resize.
I think that you have hit the nail on the head. I always question the wisdom of using stretch bolts in any application, since once you have entered the second modules of elasticity, you are one step nearer to shear. In addition, changing the forces in an engine beyond the design levels changes the load on everything in the chain, so looking at one small aspect is fairly pointless, since he rod itself, particularly at the small end, may be outside it's design loads and liable to sudden catastrophic failure. The piston itself at the rod connection may then be the the weakest link. Engineers working on large marine engines in tankers and container ships designed to run 24/7 for 30 years would never play these games.
Your video is good. I have no problem with your theory. But think about it. Did you check all the rods for roundness before installing new bolts? Let’s say you did and they were close to spec. Then you installed new bolts and they changed. Your then gonna have to press out the bolts which then takes a little of the knurls, opens the bolt holes a touch, and slightly distorts the rod and cap and send them to a shop to cut the cap and rod, press back in the bolts and resize anyways. Probably stretched the bolt a bit. Why not just resize them in the first place and they’d be perfect. I’ve sized thousands if not tens of thousands rods. We used to do tolerance tests on junk rods to see what different techniques did.
NHRAStock, so ? were the STOCK Con-Rod bolts "STRETCHED" by the factory after initial TORQUE just you stretched the ARP Bolts ??? I beLIEve the out of ROUND condition resulted from the additional TORQUE Step taken for the ARP's just an observation COOP ...................................
When you set your micrometer to the standards using the ratchet thimble or friction thimble the frame is stretched a tiny, but significant amount. When you set your bore gage with the micrometer the frame will be relaxed and the distance between the micrometer anvils will be less than indicated on the barrel. Furthermore, there is backlash between the screw and nut in the micrometer. So slight pressure. must be placed against the screw anvil when adjusting the micrometer. Depending on the wear to the micrometer nut the backlash could be more than a coup!e tenths.
so the absolute dimensions might be out by a tenth or 2, but would any of this affect the relative measurements? i.e. the same errors (in the same directions) should exist for both rod bolt measurements, right?
So - don't use ARP rod bolts if you don't want an egg shaped rod hole. You probably don't need ARP bolts unless you are racing anyway. This probably applies to any over torqued ARP or aftermarket bolts anywhere on the engine.
and if your going racing stock rods are probably not going to cut the mustard in any event, especially if you want to be competitive (unless you know the metallurgy of the rod and KNOW its strong enough)
@@Bristolcentaurus "𝘪𝘧 𝘺𝘰𝘶𝘳 𝘨𝘰𝘪𝘯𝘨 𝘳𝘢𝘤𝘪𝘯𝘨 𝘴𝘵𝘰𝘤𝘬 𝘳𝘰𝘥𝘴 𝘢𝘳𝘦 𝘱𝘳𝘰𝘣𝘢𝘣𝘭𝘺 𝘯𝘰𝘵 𝘨𝘰𝘪𝘯𝘨 𝘵𝘰 𝘤𝘶𝘵 𝘵𝘩𝘦 𝘮𝘶𝘴𝘵𝘢𝘳𝘥 𝘪𝘯 𝘢𝘯𝘺 𝘦𝘷𝘦𝘯𝘵" The class the car was built for and that he's racing in requires stock rods and other internal parts but "stock eliminator" engines are far from stock output. They're modded to make way more power than the manufacturer ever designed them to, usually aided by spinning 7500+ rpm the whole way down the track. To put that in perspective, the 5.0HO had a factory limiter of 6250 RPM and Ford didn't expect people to even regularly hit that. Watch his clutch tuning video and you'll see he has so much gearing in the car he actually needs to use 5th gear to make it to the end of the track.
Nice video. I was suspecting a change, because of the higher torque speck on the ARP bolts. Wonder if the clearence would change on new rods... I may try that same test. Thank you Sir.
Great work on minutia, but you forgot a really critical adjustment....the weight of the new bolts. ARP are REALLY serious with their strength claims, so they use hyper alloys that trash factory balance standards.....you can NEVER get back the lack of harmonics unless the entire reciprocating mass is re-balanced....weigh the stock in grams, and then the new ARP's....BIG difference!
I know I learned the hard way if you install main studs you need to align hone. My 350 Buick got the full ARP stud treatment. Ran great and would wind up to 5500 no problem. However, by 25,000 miles I was running 20psi oil pressure when hot. No knocking. I imagine it’s sloppy crank bearings.
The other question of operations, is did you leave one torqued and then change one. Retorque and change the other? Or just knock them out? That is what I have read makes the difference. When un supported you can spread the rod when forcing bolt in and out. So may have been an idea to attempt both ways, measure an alignment pin and clamp together? Takes three points to prove a line?
I'm no engineer, but I think the the difference in final torque spec would explain the size change. All other things considered, It would be interesting to see the new bolts at the same torque as the originals. i.e. if the bolts were replaced with like bolts, with the same torque spec, then would the rod need resizing?
the rod would not need resizing but you also would not have accomplished anything. the joint is strengthened by the increase in clamping force not from the bolts being stronger. the bolts are str9nger to allow you to increase the clamping force. in a joint under tension the purpose of the preload is to prevent cyclic loading. as long as the external load is less than the preload then the fastener will essentially not see cycles and will not fatigue. when torqueing to stock spec the improvement over stock will be marginal
I’ve only replaced rod bolts twice, both times Chrysler V8s. Both had to be resized. Oh and on a Cummins. The Cummins did change the rod size no doubt but it was still within spec.
Ive only built two sbc 350's my machinist did the new bolts and resizing. If i was installing new bearings and wanted to replace the rod bolts with new ones, would there be any alignment issues between the rod and cap? Or does the process of installing and torquing force the parts to align? Great demo and explanation. 👍
Some rods use dowels, but for most rods, the caps register on the bolts for alignment, so it's important to resize the rods with the new bolts at the correct torque.
1950's english motorcycles (triumph?} called out for micrometer measure of stretch of rod bolts instead of a torque wrench. that's when i learned about modulous of elasticity....a bolt is a spring. go tighten too far and bolt metal is deformed and bolt is ruined. It's important to know temperature! Cold temps and you will pull it too tight and my Norton rod bolt snapped. Ouch
Definitely not installing the new bolts by themselves. Considering pulling the engine next winter and upgrading the pistons too, while I'm in there resizing the rods for the ARP bolts.
Think people overcomplicate things and as others mentioned more power more exact things need to be (and balanced, etc.). I always check for round when I balance with the bolts that are to be used in the build. Can't balance if you "resize" the rod as it will change the weight enough in some cases. Takes about .02 seconds anyways.
2 questions: 1. Did you have to relieve the rod cap before installing the ARP bolts ? I've heard the knurling is harder and distorts the rods. 2. I'd be interested to know if one can replace STOCK rod bolts without distortion.
1. ARP bolts and nuts appeared to fit fine. 2. I would expect replacing the stock bolts with the same bolts, and using the same preload (torque, or ideally, stretch) would result in the same shape of the rod, so no resizing needed. But then you don't get any performance advantage...
Thanks, and normally, yes. During resizing the cap mating surfaces are cut, making the big end a smaller oval-like shape. It's then honed back to the nominal size round shape.
I rebuilt my first engine at 15 a 289 out of a $200 Mustang. I unlike you didn't do any testing. Since I was going to put four barrel on it I had to " make it full race" and torque the rod bolts to 35 and I forget what I torque the main to. My friend's dad came over to see how I was doing and when I told him the motor was almost impossible to turn over by hand he asked me what I had torque things to. Once he realized what I have done he helped me take apart the motor again and correctly assemble it. So this was an entertaining video for me
I have found mismatched rod caps or main caps that caused problems for young builders including me. Back then it was supposed to be a good thing that it was hard to turn over that meant that rings would seal and oil pressure would be great.
Interesting. Thanks for explaining your method of verifying the C clamp is a precision device now....I feel this has helped me understand some measuring tools.... I want to check the wear on a subaru engine piston bore, so a tool like this and properly measure 3 & 9 and 6 &12 positions as you move up the wall...maybe focus on the highest wear area ? just below the TDC of the piston.... thanks.
@@The_Performance_Laboratory There are many levels of learning and understanding. Your video here helped, like the heart of the Grinch, it grew that day...
I think resizing the rod bearings would have to be on of the the riskier jobs in the balancing process. I can see why so many people go out and just buy expensive high-quality I-BEAMS or H-BEAMS because the risk is so much lower that everything will be right.
When clamping a rod in a vise it should be done on the big end of the rod just before the parting line generally. After resizing a rod you can change the bolts using the same style & brand bolt if done properly. Bill Jenkins addresses this in a couple of his books. I have done this myself with no problems. The rod must be torqued and securely clamped over the parting line doing one bolt and retorque at a time. Always re-check sizing. Don't clamp a rod on the small end of the rod, avoid twisting the beam. I've resized so many connecting rods in my life I've lost count. Also its a good idea to change the nuts after a few retorquings.
Many years ago apps 35 . before I had access to people who could resize rods (I now have a rod hone) I put many sets of bolts in without resizing. I would reduce the press fit of the unfurl to close. To the size of the ones I removed and install them if they where less than 001 out of round I used them. Don't recall having a problem.
Can you measure the diameter of the bolts where the caps meet? Seems to me the cap is spreading outward with the stronger bolts, wonder if this is helped by a dimensional difference in the bolt? Or excess clearance in the dowels?
Ovality was within spec with original bolts. Ovality out of spec with new bolts. The issue isn’t with the bolts being torque to yield, it’s with that torque being excessive and distorting the rod. Lesson for the day is standard rods = manufacturer’s torque spec regardless of fastener choice because the rod can only deliver so much crush before distortion.
We used to run a 350SBC up to 9200RPM, but it was a purpose built race engine, usually rods are around 35ft lbs mains are usually 65ft lbs if I remember correctly on a 350 SBC that is been 20 yrs since I built one
The problem is, the cost of new bolts, installing and paying a machine shop gets the cost darn close to what a set of Eagle or Scat rods cost. You are left with a factory rod this is bit stronger than the stock one. shot peen and polish the beams it might last a bit longer. Drop in an Eagle rod and you will not have to worry about the connecting rod - especially if your running something like an old Pontiac (cast iron rods? really?)
ARP bolts are $80. The local shop charges $100 for resizing plus $25 to make sure they aren't bent or twisted. So that's $215. Scat forged rods are $380 shipped. For $160 I get a much better forged rod.
I built a 427 bbc decades ago. Replace 3/8 rod bolts with arp. Didn't resize them. Lots of street miles and numerous 7000rpm Rev limiter hits never an issue
Nope. Rplaced the rod bolts in my LS Vtec with ARP and did not resize the rods. Had 0 issues and no bearing wear. Daily drove that motor for 5 years and beat it pretty hard at times. Wish I would not habe sold that Civic.
this. also, he used the wrong gauge. i replaced the rod bolts in my 400 cu in big block v8 mopar with arp bolts, and never resized them. runs damn good.
Ok question for you: rebuilding a 5.0 and the bottom end looked decent (explorer motor / was cared for). Planning to reuse the rods / boring .030 because new pistons are within 5grams of old so I don’t plan to rebalance. Targeting ~300hp street motor but might wind it to 6k here/there. Would you add the ARPs to the rods? Mic’ed the rods and they are in spec. Also - did you check twist on yours? Might mount mine in the lathe and check with an indicator too. Alternative plan is to order full rotating asm from summit but only if necessary (ie- reuse is too risky) Opinions welcome / what would you do?
If it's just a street motor that won't see much RPM too often, you're probably fine with the stock bolts if the rest of the rod specs check out. But if you're going to lean on it regularly, you'll sleep better with the better bolts and resized rods.
Here we go "ANOTHER ENGINEER MAKING HIS OWN DECISIONS--NOT CALLING THE MANUFACTURER WHEN SPECIFICATIONS CONFLICT"--which only the manufacturer would know. Nothing like scratching your ^ss and calling it good!
not sure about the resizing point - lateral movement - if you have lateral movement the bolt shank is the wrong size (too small), if you up the bolt torque and this causes distortion that suggests you have issues with distortion and therefore down stream issues with heat treat and temper (insufficient RC hardness) In addition the route you seem to be going implies that rod bolts are single use - do it up once throw it in the bin as the second time round will exceed the stretch limit and the bolt will be out of spec - more fundamental question is - is the metallurgy of the stock rod suitable for the increased tension of the HP bolts? or should you get hp rods which come with up rated bolts? second question if your using stretch as your measure how many times can you do up (stretch) a bolt before its out of spec?
The ARP (and stock) rod bolts are not torque to yield, so can be reused as long as they're not overtorqued beyond the yield point. There was no lateral movement, everything was a tight fit. Hardness does not affect stiffness, and thus distortion. Stronger rod bolts allow higher preload (which allows for greater rod loading), but create greater distortion from the higher preload, thus making the rod out of round, and requiring resizing.
That is odd. It is as though there is more metal to the outside of the bolt than the inside and that is probably true. Which suggests the fix is fine sand paper on a surface plate with one side of the cap slightly raised to bias the mating surface. *I wonder how round it is with no toque?
As a machine shop owner I think you failed to mention the stress of removing the old bolts and pressing the new bolts in place. The majority of ARP rod bolts need to be pressed into the rod and that induces stress into the rod bore causing deformation. The test you performed would be better suited with a capscrew only connecting rod because no additional stresses would be introduced with a capscrew only set up.
The stock rod bolts were also pressed in, with what appeared to be a similar interference fit. But I think you missed the fundamental point of the video: you can't just replace rod bolts without resizing the rods, because regardless of how the stresses are created/altered, it affects the size of the big end.
@@The_Performance_Laboratory you missed the fundamental point because you forgot to mention it or even show replacing the bolts in the video! Yes the stock bolts were pressed in but then sized afterwards in the manufacturing process. Your video failed because you blamed the deformation on the new bolts without mentioning the stress of new bolt insertion had on your outcome. That is why I said your test would be better suited to a capscrew only rod because there would no other stress influences , only the stress of the different grade of fastener.
@@The_Performance_Laboratory your conclusion which is typically true in automotive style rods doesn't apply to every connecting rod in production. I rebuilt lots of medium duty diesel rods of a capscrew design. They use a one time use stretch bolt. I have yet to meet a customer who was willing to buy two new sets of new bolts, one set for me to use in the resizing process and another set for final assembly(that scenario also has its own flaws by using two different sets of bolts). I torque and degree the old bolts during resizing process and when I have tested the dimensions with new bolts after the resizing process and it was always within a tenth. Several older agricultural based engines required rod bolt replacement at certain intervals without removal from the engine.
@@andrewevans1658 I think you are going deeper into the question than is required to answer the question. You make many valid points, but the question was "do I have to resize if I put in ARP bolts?" The answer, regardless of all the points you make, is YES. Now if you wanted to root out just what would happen with ARP fasteners in a capscrew style rod, that would be a different and interesting video. Maybe you could make that one?
@@999torino he didn't show replacing the bolts on video or explain the stress that induces and blamed it all on the bolt and as an engineer he should know better. I am in the process of starting a channel and yes a capscrew video would show that the fastener alone has virtually no impact or very little.
