I believe you are wrong, Where the roller touches the valve stem is where the line should be drawn to (but you can't) Don't believe me? Draw a right angle on a piece of paper, place the Rocker's Trunnion center on the Horizontal line with the Roller tip on the Vertical line at a 45. Sweep the rocker through the arc (I place a small white dot on the side of the roller tip) and see where arc is and you'll notice it is on the Tip of the roller is where the true center of the fulcrum should be. Kind of makes sense it would be at the tip eh?. (at least for my roller rocker)
I have a set of older TFS twisted wedge heads on my Corvette. They require different rockers and pushrods for intake and exhaust. The sharpie marker method is exactly what I used to get it right. Good advice and great video explanation.
you need to point out this procedure is at the base of the cam lobe, you also need to point out this includes the head gasket and head is torqued to spec.
I did mine with the mid lift method, but the roller is out on the exhaust side closer to the edge. It's a sbc with a hydraulic roller and + .100" valves. If I put the sweep in the center, the patern is about .125" wide. With it out about 3/4 of the way out, it's only around .050" wide. I haven't fired it up yet, but I'm thinking of putting lash caps on it just to be safe. Got any advice? Scorpion 1.5 rockers btw.
I have an idea... once you have your first line. There should be some kind of simple math that would allow you to calculate the angle to make a 90° at full closed. I'm sure it would change depending on cam lift :/ If that is possible though. all you would need is one of those cheap angle finders and mark your closed line off of the smooth edge of some masking tape. Then use the smooth edge of the tape as the line in the video and not even need to make a mark on the rocker.
The proper method isn't primarily a "BULLSEYE" center stem pattern, but the minimum RA from/back ARC swing movement. That will translate to the most full transfer to linear vlv movement.
Needing to find pushrod length for my build, the cam I installed has different lift for intake and exhaust so for proper geometry I should run different length pushrods?
go to lowes and get a laser that shoots the + dual lines and use that to check the 90 degrees, much better than a sharpie, on line on the valve stem, one line for the rocker
You are a genius. What is that guage that's measuring how far down the spring is going called? I should get one of those and try this method. I'm using pedastal non adjustable rockers though, but I'm assuming I could accomplish the same thing with shims? I don't know....I'm just trying to do a GT40P head swap on my mustang with an explorer intake and custom cam. Nothing too major, but I want to do it right the first time.
this is BY FAR the best video I've seen. but I have a question since I'm learning. do you not need some softer springs to do this?? I've seen it on some other videos and hears it before. thanks keep it coming !!
You don't need soft springs. In fact, you don't need to compress the springs at all. That's one of the real benefits of this method, is you can do it in the car without turning the motor over. Just make sure the lifter is o the base circle, get your initial 90* relationship and it's just math from there.
Although it helps in aiding longevity to the checker tool and the amount of re-uses it will give if the checker tool is of good quality you can compress a single spring w/damper without removing them to test.. I do the check with the regular pushrod I have on hand and a dial indicator..I get the valve to half lift and see how much it takes to get the fulcrum to roller tip centerline to 90* with the valve subtract the two and thats how much longer of a pushrod I'll need and vice versa.......Been doing it that way over 35yrs. and never a problem..
I have a Chevy 01 cavalier 2.2. 134l that I have built for oval track and would like to put roller rockers on but have no idea what components to use I would have to tap the head for studs. I believe the ratio is 1.5 stock camshaft with hydraulic lifters. It has pedestal mount rockers now but the bolts are very light duty and I am running 6500# valve springs. Just rotating the motor broke one of the studs off. I believe they have to be self aligning rockers. I seen this motor with roller rockers so I know it can be done I just don't know what parts I need to accomplish what I want to do, any help would be greatly appreciated,thx
Are high quality roller rocker arms best for all automotive gasoline piston/cylinder engines (from the humble little 4 banger all the way up to those monster V-12's and beyond)? If not, couldyou cite examples of where would rollers work best?
I tried using this method, but in order to establish the 90 degree angle (with valve closed) and getting the mid lift, I need to have longer rocker studs. What am I doing wrong?
I'm trying you're method but i have Howard's link bar lifters(ford 289) When you spin the motor to check 45 degrees angle at half lift my plunjer in the hydraulic lifter will collapse .also when checking valve tip mark. Doesn't it give you a false reading? Thanks
You can put a washer or two under the stud just for measuring purposes. If the stud is too short for the initial 90* setting, it usually means you need longer studs.
I had an engine built 20 years ago. The pushrods were too long and the rocker rolled off the edge of the valve tip and ruined the valves . Now I know how to find the right pushrod length but what about the lash? Doesnt that change the geometry? I'm running a hydraulic roller. 0 lash then a half turn preload is my understanding. Is it that the lash won't make enough of a difference to throw the geometry off? I had a head gasket problem. Can this be caused by the incomplete lift of the valves and getting a lean condition that blew the head gasket. It's a 347 vortec V1 s trim with ported first gen twist wedge.
Irs probably a solid roller You do it one if two ways You either buy a solid lifter and use you regular springs or you buy checking springs and use the exact lifter youre gonna use If you use regular springs then yes you would be right about not truning it over if it has a hydralic lifter
He's looking at the valve stem vs the line he drew on the rocker If you look at it theyre 90 degrees to each other and the roller ia centered over the top of the vakve stem
@@19jody72 do you have a checking pushrod? The comp cams magnum ones are the ones most people use because its marked with measurements so you know exactly what size it is
@@serracon Hello Sr.! I was wondering if I could ask you a question. My camshaft is .520 .544 do I make the math from .544 lift? So half lift would be .272? Thank you in advance and thanks for the video.
Good lesson but that $13 tool they make now takes all that work away lol just set it on in place of the rocker and bring pushrod checker up to it and there u go
Those are worthless, different lift cams will need different pushrods on a stud mount setup to achieve 90 degrees at half lift. A shaft rocker setup will need the shaft height set so the rocker is 90 degrees to the valve at half lift.
@@jeffreydurham5342 yeah theres a guy on here who builds racing engines shows that and drawing a centerline through the rocker tip and the roller fulcrum with a sharpie and setting it at 90 then going back and checking it with the method here. If they match its a go
Good video but you drew the wrong line on your rocker arm. The line of action is from the rocker pivot to the roller contact point, not the roller center. The valve only cares about what contacts it, the roller OD.
