Following on from the last episode, I get into exactly why the Duetto Spider's engine was so noisy. Turns out it was a bad line bore sometime in the past. Instagram @jethrojamesbronner #ClassicCar #Restoration #AlfaRomeo
Amazing restorations - I remember 1973 - The Oil Crisis, when all Gasoline Stations in SA closed on a Friday at 6:00pm and only opened up at 6:00am on Monday - I drove with my friend in his Alfa Giulietta from College in Pretoria to Cape Town for the long Weekend. We stored Gasoline in the Trunk using empty 25liter paraffin cans, the square ones, as they packed perfectly in the trunk. We made the first leg near to Bloemfontein and filled up and then drove carefully all the way through the Northern Cape, through the Karoo on to Cape Town on our gasoline cans. Wonderful little car and brings back memories of a bygone era. Now, I am relegated to driving a gas guzzling Cayenne Twin Turbo V8 and driving my 1991 Fiat Turbo Uno in Cape Town when I come back to SA. Keep up the good work. Never throw any classic car away!
Im a mechanic, and i did some NA engine builds (Lada 8v SOHC) with crazy camshafts, like 296 and 316/304. These engines always needed enlarged valve pockets, otherwise it wouldnt even turn over :D So the easiest method; Get a valve that is 2mm larger diameter than your current valves in your engine. Make sure it that its leg fits you cyl head perfectly, and it is long enough for you can reach it with a drill on the cyl head. Now shape it like a router with an angle grinder. On the side, and bottom too! Get the piston in TDC in the block, bput on cyl head with used gasket, and you can route the exact amount out that you need.
Maybe run a spacer plate, laser cut from sheet steel in the shape of the headgasket by a machine shop, like ones used to lower compression for adding a turbo?
My day has been made since a new Jethro video showed up. It's cool to follow your investigation as to what caused the failure. You are very well versed in these Alfa drivetrains 🔥🔥💯 Everyone makes mistakes, but you were man enough to recognize them and learn from it. I'm definitely gonna keep an eye out for this build. Good luck my friend!
Welcome back Jethro,always a pleasure to watch and enjoy your excellent videos. God only knows how many engines and other mechanical components of Alfa 105 cars have been butchered over the years by lazy,incompetent mechanics with a penchant for always looking for short cuts and cheap repairs as a way to keep these cars on the road . Giving these well engineered cars a bad name and reputation. Hope your fix for this engine works well.
After all that work building the engine it would be heartbreaking to have it not run. Great detective work on finding the issue. I am sure you will be able to sort it out and make it run like new again though.
As mentioned use a copper shim, standard with old XK engines, especially 3.8 litre solves lack of old 5 star leaded petrol by dropping the compression ratio and any skimmed heads with valve to piston clearance problems. have done this on a 3.4 XK120 and a 3.8 E Type with no ill effects.
Oh dear Jethro, not good finding a problem like this so deep in the engine after completing a full rebuild. It's easy to blame yourself, but that's hindsight for you. You have fantastic knowledge and skill working on Alfas, similar to Iain Tyrell and the cars he works on. It makes for great viewing and I look forward to seeing you work on this problem.
Thanks Jethro for sharing such a rare issue in this so reliable block. You are very brave to start (almost) all over again. I look forward to see the next works.
Great to walk through all this with you and learn along together. Even if it never ran again.....those blocks are still gorgeous enough to display in any living room!
Quite a storm sounds like going on outside, could also tell by the water on the glasses and the wet hair. Nonetheless amazing video as always! One of these days your channel will get noticed and pick up massively, I have no doubt, the production value is astronomical and the pure mechanical content is aligned with any car enthusiast's ideal idea of a car channel. Amazing job good sir
Whoa! Brave man that you are! You couldn't have realised these problems before hand! Full credit for your breakdown appraisals! 👍 I'll be looking forward to watching where you go from here....👌
Hey Jethro... great detective work! I def recommend speaking to Redline gaskets in Cape Town, very helpful bunch, and really good value. Regarding the alignment, I had an Opel 2L than had to be line-bored higher (cast iron), and the oil seals and alignment dowels for the Gearbox were moved succesfully. Best of luck! - A Duetto with original motor is a special thing!
Great Video, Jethro. Just do what is needed to put the heart into that amazing car. OH!!! What a start for a video!! Seeing a classic Giulia always brings back memories. We had a 1967 Giulia Super 1.6. As a sick, "Alfa Nut" myself, I wish we were neighbors. Keep on working!
That is awesome trouble shooting the problem. I agree with some comments with shims and copper gaskets. Also is there a possibility of slightly grinding a clearance on the piston and valve sides just enough to get it working. Setting the valve in a drill press and slightly touch the edge of the valve with a fine tooth file then 500 grit sandpaper so no sharp edges. Good luck fixing it.
Wow I’m glad you’re knowledgeable of the impact of such tolerances and oil channels in the block - looking forward to more videos Jethro as any Alfa content from you is so enjoyable to watch 👍
So glad to get another video from you Jethro even if just to share what happened to the engine. Really looking forward to the next vids on building it back!
If you weren’t already intimately familiar with these engines, how would you have ever made this diagnosis? It’s frustrating. No matter how much experience I gain working on my own car, I’ll never know what this guy knows. How did you gain all this knowledge Jethro? It’s obviously not just from experience. You have had some mentors, I think. Share your story?
To be fair though: if (!) the there's nothing wrong with the timings, if stock or close to stock camshafts are being used, if the valve guides are straight, if the valve seats are fine, if the correct valve clearance is there and there are stock pistons and rods are being used then there are just 2 reasons left why valves and pistons come into contact: a) someone machined down head and/or block (maybe to gain compressino, maybe because it wasn't flat, maybe because they botched the job) b) the whole bottom end with crankshaft, rods and pistons came up. If it's a) you can check the overhang of the liners to rule out machining on the block and you can measure the thickness of the head. If you ruled out both it has to be b). Then it's time to check the main bearings and the crankshaft. Of course, takes time, tools and lots of experience to do all of that right and potentially even more knowledge and experience to fix it.
@@diotough Good post, but just saying, if it’s me: - measuring cams, valves, pistons would take me hours, and 0.5mm is probably inside my margin of error anyway - I would never expect that (a) would result in interference; I’d have expected any interference to cause a catastrophic failure - (b) would absolutely never occur to me Which is why it might have taken me weeks - or forever - to diagnose this. My only hope is videos like this to help me in times like that.
Sorry to hear bud, I've junked a few rare blocks because of previous machining and it's frustrating. I've not heard of mains being welded up to create surface for line boring so keep us posted, and remember stumbling blocks can be turned into stepping stones - doing something right requires knowing how it's done wrong.
Why not put a shim between the cylinder head and the block? It would be simple to manufacture. Perhaps use copper which would deform to make a good seal.
neville if the bearings are in ok condition it seems like the logical thing to do. Check the valves are still straight and he should still be good to go.
I think now he knows the issue he wants to fix the root cause of the problem. An engineer / perfectionist wants to really sort these things out properly not just get it running ok. It will also sort all the other potential issues. You really need to trust the machine shop you give that work to though. Really great to see a perfectionist at work rather than than the oh so common ‘oh that’ll do’.
That would give the Piston to valve more clearance you need at least 70 to a hundred thousands of clearance between both items so it does not interfere with each other during running conditions especially at high speed
@@JethroBronner Jethro Bronner Try contacting Victor Reinz, Ajusa or OKP and explain them your situation. They manufacture head gaskets for your engine. Hope they can help you out
Years ago I also had the same kind of problem with an engineering shop. It just shows that when you take it to the engineers, it is not a given that they will do the job correctly.
Great update 👍 I’ve noticed some people mentioning a spacer in the head gasket or a thicker head gasket, this will lower the compression & give the clearance, a lot less work & this type of fix is quite common. ✨🚙✨
There are reasonable ways to fix the valve/piston clearance issues, e.g. new(shorter) or machined pistons or thicker head gasket if readily available to offset increased piston travel path. However I'm curious about mating offset crankshaft/flywheel with transmission, that seems like a bigger issue to me. Thanks for sharing and looking forward to more updates, love your attention to details and shop setup.
I had a similar issue with a Mitsubishi 4g63 with a shaved head. I found a standard head and a thicker HKS head gasket and that was enough to do it. Good luck and hopefully it’s not too much work
Nice that you care about keeping the car original. Of I had this situation I would stick a good and biggee block in it. Looking forward to the next episode!
Great diagnosis, analysis and explanation Jethro. Very informative and helpful. Not possible to correct that situation with oversized bearings and a different head that is closer to the specified thickness?
Cowboys bodged it before... With the crank too high, not good. Thicker head gasket should be a simple way forward. Cut one from copper if not commercially available. I'd worry about oil seal life. Might be better to get the crank back in the right place and add the race mods for the crank oil ways. Expensive, but keeps it original and gives you peace of mind/fewer hassles in future. Especially if you decide to update the motor.
All that's been done is the main caps faces have been machined off and the tunnel machined back to size. The seal housing can be re-done by coming off the main bearing and just go up in size on the seal O/D untill it just cleans up at a size of seal readily available. As far as the compression ratio is concerned, 0.015" is not a great deal.
Hello Jethro, which cylinder head gasket are you using? The quality is getting worse and worse and the gaskets are getting thinner, even with the old brands, the thickness should be 1,6 to 1,9 mm, I recently got one under 1 mm directly into the trash. Good luck
I'm using the Victor Reinz head gasket on this one. Even that one is only like 1.4mm. I'll check on the new gasket that I have for this car. I've been watching your channel lately to help with my German, looking forward to seeing how the new paint on your GT looks.
@@JethroBronner i hope it helps you a little bit, i am very happy about that. i follow you too :) too bad it is so far away .... let us know how it goes on with the engine
@@JethroBronner 1.4mm is too little. The cyinder head will be from the head dimension also already under tolerance, which means it was planned already more than once, or planned too much, as I said before you need a 1.9 mm head gasket or a new head. One does not notice it if one turns the engine by hand, you notice it only if the engine runs.
Ughh I hate that, the Duetto looks so beautiful I was excited for the project to be a runner! But alas, problems happen, if you didnt have patience you wouldn't have an Alfa! Im impressed at the level of inspection you went through to find the miniscule (yet catastrophic)faults. Is there a valve-piston clearance test you can run next go round? I believe thats normally needed for high compression race Nords, I wouldn't have expected it on a stock standard 1600
Have you considered having the block re line bored back to the correct location and have oversize bearing shells fitted? Could have the oil feed issue addressed at the same time? Quite a common job for us to do on race engines that have spun bearings due to oil feed issues under high cornering loads.
This is what they call tolerance build up where parts get machined too much to the point where there is insufficient clearance between moving parts. Porsche flat six engines also can suffer from this problem, which the engine builder will use shims on the bottom of the cylinders to achieve proper deck height. This entails careful machining of cylinder heads to also achieve proper depth to avoid valve interference issues. On the Alfa, if the cylinder head is machined to it's maximum limit may require an oversize head gasket. The machine shop should not had machined into the block as far without realising you would have these issues later on.
Did you notice anything funny when doing the plastigauge when installing the new main bearings? I'd think if you used oversized bearings because the crank was ground, they'd still be loose because the block main bearing surfaces were bored out 0.015, and that would show when plastigauge used?
Did I miss you saying how you plan to avoid this problem of the valves hitting the valve pockets when you rebuild? Will you have to re-machine the pistons? As far as I know there are no thicker head gaskets available for these engines. I'm sorry this happened, but we all learn a lot by your misfortune. Thanks very much for sharing this.
Hi Bruce. I'll be doing a series of videos about the rebuild, where I'll show exactly what I'm doing to address all the issues caused by the line boring. It has other issues other than the valve noise. Yeah I've certainly learned a lesson from all of this!
I am not sure I understand why the new larger tunnel bore is not concentric with the old bore. That can only be a machining error, because normally after line boring, the tunnel is in the same place even if larger. I have had my cars' engines line bored quite a few times and never had a problem of this kind. .4mm is also a lot. I don't think I ever needed to take away more than .1mm. Be that as it may. So the new bore is up .4mm from the old one. If that is the case, you can have the crank spray welded and machined to compensate for the upwards move of the tunnel. This means you will reduce stroke by .4mm. Not ideal but it would work and it's simple, easy and cheap. The other option is to have bearings made up for your block as is. There are companies that can make you a set of bearings to your specs and these can be eccentric, to bring the crank down by .4mm or however much you need. I would take the second option because that would help solve the misalignment problem with the seals and g'box as well (the first option is easier and cheaper though). These options have the merit that they leave the head alone since that is not the problem anyway. All said, now I think we know why the last owner sold the car.
Any chance you can get the valve pockets milled out a little for your clearance? Or can a thicker head gasket do the trick, it will lower the compression? NOT sure if even a .080 gasket has even been made for that motor.
@@JethroBronner Nice! It should have absolutely no effect on compression or at least not enough to make a difference. The Duetto is so clean I love just looking at it!
Hey Jethro, how about machining the pistons to clear the valves? Easy fix with simple machining, and you will still have plenty of compression as the head has been machined 0.5mm. :-) This would give you the clearances you need to eliminate any concerns going forward.
It's all part of build life Jethro..... I'm glad you took responsibility for the over sight... Now let's make it a bad ass duetto. Put some valve clearance on the pistons and let's move on.... Oops. Question. How can you not rev an Alfa?
Hi Jethro.... thanks for the videos.... I have a question about cleanliness.... I assume the cylinder block in the video is alloy?.... how are you getting it so clean?..... what are you using to achieve this. Im in Botswana so perhaps have the same materials as you can get in SA?
Nearly 40 years ago we restored a guilia GTC with the 1600 in it. We were youngsters and didn't really know what we were doing. Anyway it never quite ran right so we took it to a specialist engine builder. He eventually diagnosed that the con rods only go in one way and we had it wrong. Any idea if this is possible? It certainly ran better after. My friend still owns the car.
Wow a GTC is a very rare and special car. Yes the con rods are offset, so if you put them in the wrong way round it will cause lots of friction on one side of the piston.
Nope. As Jethro explained the problem is the position of the crank inside the block, nearly .5mm. In engine terms it's a huge change. The simpler method is to machine the pistons to accommodate the valves, but the underlying issue isn't really solved. I wonder if it would not be possible to fabricate shims for the block and then use an unmolested set of bearing caps to resolve the crank location issue?
Have the valve seats been replaced ? If they have and the valve no longer sits sufficiently into the head, this could generate the issue. Try comparing with a stock head with original valves and seats.
I'm no engineer but you can also work on the pistons making the valve pockets a bit bigger or deeper so the valves don't hit them. Higher compression is not a problem if the cylinder heads can take it. Another way is using a head gasket a bit thicker that the original one, it gives you less compression and more space for valves and pistons. What do you think?
I've built engine for decades and I can't even begin to imagine that 15 thou would make any difference. It's not actually more stroke, it's just 15 thou higher up. You don't need different cams to run different compression and I don't think 15 thou is going to make any real difference. If it's going to hit, shave a bit off the pistons and polish the chambers. The line bore shouldn't have changed anything, they just open it up, it should have had the same center. You don't offset the center.
Wow, I did not see that coming. Kudo's for gaining the knowledge to figure this out and measure properly. Don't feel defeated! So..dumb question- can you get away with a thicker head gasket to solve this issue? I know that we used to get thicker hg's on our old BMW's to lower compression for turbo applications...
That would be an ideal solution, but I can't find anything like that for Alfa 105 engines, and I definitely don't have the technical know how to develop one.
Hi Jethro, well done on the fault finding. Surely any line boring would have been with the caps in place and therefore the same amount of metal will have been removed from the caps? If this is the case, then I don’t see how crank is any higher in the block? Could O/D oversize bearings be sourced?
So the issue is that the damage from the 2nd main bearing spinning removed metal from the block, and they line bored into the block to remove the damage. They also cut down the caps a little bit too.
You can end up with ignition issues like detonation. A high lift cam will change where the power is over the rev range, making it less likely that you'll have a detonation in the mid range and lower range. High lift cams, because they have so much overlap, let out quite a lot of gas, which is why they usually run with high compression pistons, it will offset that effect.
Even if the line bore took off more material than standard, cant you make the difference with oversized bearings like normal and the crank will be in the standard position? or is there something with alfa engines that i'm not understanding.
I guess I’m missing something here. The line bore was oversized and would require oversized bearings which would restore the crank to the original position, no?
In some cases, larger outer diameter main bearings are available for line bored engines. This applies to air cooled VW and Porsche engine cases which are alloy as well. It would be nice if Alfa engined had these oversize diameter mains... Best of luck! Cheers!
