Say any given cam and the pushrod length was spot on. If the rockers were changed to full roller and the same ratio, will the PR length be the same? Yes, I realize it should be checked, and I’ll do as I’ve done before and use one of the old PRs and make it adjustable to check/verify. I’m just curious what to expect.
Due to the ratio of the roller rocker's being more accurate than a stamped rocker, I'd expect to have to get different pushrod's. You might get lucky though.
Well I’ll need hardened push rods anyways, so will make one of the old ones adjustable. I’ve never run a roller tip/full roller, didn’t know if the roller and rocker was in the same place/height as the dimple is in the stamped ones. Thanks.
Of course changing from flat tappet to roller will change pushrod length. How much, or what length you need will be determined by what roller lifters you use. You'll need to buy or build an adjustable pushrod to see what length you need. Once you find out there's a good chance one of the cam makers, or pushrod makers will have a common length that fits. My SBC 350 is a 1990 roller motor, so when I installed the Howards roller cam I went with factory style roller lifters, with Crane 1.5 ratio roller rockers, and after measuring I found numerous sources for hardened pushrods in that length.
I ran a flat tappet roller cam, an Isky rev kit, Crane roller rockers and stock length push rods. I had the cast iron off road angle plug heads with the screw in studs and guide plates. That setup never caused any problems. The engines were SBC 350, 377, and 400. They all ran great. Of course that was back in the mid 70's to the late 80's.
Really...there's no need in asking here !! Only you...will know, when you install the new rocker's and...check for correct length ! Mike
Manley makes a pushrod length checking tool for a variety of engines. Jeg's price for the Manley small block Chevy engine part no. 660-42132 is $17.57.
If you are working on a Chevy and use a pushrod length checker, that takes the place of the rocker arm, then how could it matter what type rocker arm you use?
The only way to know is to color the tip of the valve with ****m or sharpie and pattern it. The tool from Manley might work ok with stock rockers but rollers are a different matter. There will be differences from brand to brand. Get your pattern in the center and as narrow as possible and you'll be golden.
I made my own adjustable push rod by cutting out a section and taping both ends for all thread and locking nuts. With adjustable rockers it’s easier to get the geometry pretty close. I send off the pushrod most of the time when ordering.. I always made sure to request it back.
If I read the original post correctly,,,,,,he asked about using roller rockers,,,,,, not a roller cam . And the blue tool that Jim posted is the correct tool to check the pushrod length with . It will be dead on ,,,,on a stud mounted rocker system . Tommy
If you are going to buy new roller rocker arms, why not look into getting a longer ratio at the same time for a performance gain...........if you have some room for piston clearance? As for all roller rocker arms by all aftermarket manufacturers needing the exact same length pushrods when bolted to your engine........check twice/buy once. I'd buy a ready made length checker, they are cheap and Amazin delivers free www.amazon.com/Performance-Adjustable-range-length-checker/dp/B09NR419SH/ref=sr_1_1?crid=3UP7O2YT4DA4T&dib=eyJ2IjoiMSJ9.vAmd9lY_OOE1TM1lZbvYCift3tsdZ43iSRYX0FM0DLHcaRjSqpqXb1UXktFOcs_V5Ep0GtPeE5CzDpvNDwdJ0hIf4M9S61yL1-B2XQKbiLma1v2_ivD3Ceh3cUqrQcB8FGyLqRTPoATD4UHWpf03NP0LHemOUiDILRIjVl45vbZYkv87-EPOd9f_ls8EfiGPGkhQ1cIWV7CS78LnNjYHU3i_nZTlHgDtkEVHCqKJEeQ.lXBPCzGNAI8NMd4p9nJug9J2duNx5bkICyvu3yazQRI&dib_tag=se&keywords=pushrod+length+checker&qid=1709155214&sprefix=pushrod+length+checker%2Caps%2C281&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1
I failed to mention the cam is hydraulic roller, iirc the lift is in the .470 intake range, exhaust is .485 with 1.5 rockers. I’ve done the same with PRs before, cut, tap and make them adjustable. As I mentioned I’ve never used roller rockers, so wasn’t sure what I’d see. It was a “I wonder about” question. Thanks all
I think the answer is yes for any make of engine. For instance on the Ford 1978-up small block, the stock bolt on rocker arms can be replaced with bolt on full rollers and everything still lines up and works fine.
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