Noisy 302
Logistics Pro
Joined: Aug 2014
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Did you measure correctly?
Even a 0.020"–0.060" change matters, so 0.200" is a significant difference in valvetrain geometry
Even a 0.020"–0.060" change matters, so 0.200" is a significant difference in valvetrain geometry
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Lead Driver
Joined: Dec 2002
Posts: 5,493
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From: Kuna ID
Unfortunately I don’t have a tool for that. We just found the closest size to stock and went with it. I just don’t understand how a cam that should work with stock pushrods and lifters that should work with stock pushrods don’t. I figured if the pushrods were too long we could shim the rockers?
Hotshot
Joined: Jun 2015
Posts: 12,885
Likes: 2,448
That depends….. did the OP remove a roller cam because the new cam is a roller.
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Hotshot
Joined: Jun 2015
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I removed the flat tappet in my ‘89 and installed a roller cam with GT40 heads and Scorpion rocker arms. The pushrod checker tool came up with stock length roller cam pushrods.
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Lead Driver
Joined: Dec 2002
Posts: 5,493
Likes: 16
From: Kuna ID
The new pushrods were too long which I thought they would be but it was taking 4-5 shims to even them out. Right now we are thinking about a rocker stud conversion kit and running some adjustable roller rockers. I even tried a new rocker arm just in case the old ones were really worn out but no luck.
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Lead Driver
Joined: Dec 2002
Posts: 5,493
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From: Kuna ID
Another thing I have been pondering is just getting some screw in studs and using older style adjustable rockers like the ones on the 1969 351w in my old mustang. They are adjustable and don’t require guide plates as the valve side of the rocker has lips that keep it centered over the tip of the valve stem.
I have also contacted summit about the cam and they have no answer as to why the stock pushrods won’t work.
I have also contacted summit about the cam and they have no answer as to why the stock pushrods won’t work.
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Joined: Feb 2020
Posts: 322
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From: Ohio,Georgia,Nevada,Texas
OP,
This is a bit of an odd one. The Comp CCA-35-512-8 should use a 6.248" stock length pushrod in a factory roller 302. Adding lift does take away from the base circle, but this isn't a "big" cam, and Comp calls it out as working with stock pushrods, so that alone shouldn't make the pushrods seem drastically too short.
Something else in the valvetrain stack is likely causing the discrepancy in pushrod length.
At this point, you could either check the valvetrain geometry with a pushrod length checker and dial caliper or convert it to a stud-mount adjustable roller rocker and give yourself some adjustment range there.
Either way, you still want good geometry. Even with adjustable rockers, you’d still want to verify preload, rocker sweep pattern, etc. For those Ford Performance lifters, Ford recommends around .020"-.060" preload, or roughly 1/4 to 3/4 turn past zero lash.
This is a bit of an odd one. The Comp CCA-35-512-8 should use a 6.248" stock length pushrod in a factory roller 302. Adding lift does take away from the base circle, but this isn't a "big" cam, and Comp calls it out as working with stock pushrods, so that alone shouldn't make the pushrods seem drastically too short.
Something else in the valvetrain stack is likely causing the discrepancy in pushrod length.
- Lifter seat height
- Collapsed or fast-bleed lifters
- Valve tip height
- Pedestal/rocker stack differences
At this point, you could either check the valvetrain geometry with a pushrod length checker and dial caliper or convert it to a stud-mount adjustable roller rocker and give yourself some adjustment range there.
Either way, you still want good geometry. Even with adjustable rockers, you’d still want to verify preload, rocker sweep pattern, etc. For those Ford Performance lifters, Ford recommends around .020"-.060" preload, or roughly 1/4 to 3/4 turn past zero lash.
Cross-Country
Joined: Jan 2024
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My 78 f-250 have dummy gauges same with my 89 f150 and 90 f-250.