Pushrod question hheellpppppppp!!!

XxSlowpokexX

Registered User
Seriously. So I get the new heads on, try my stock pushrods....I hand tighten and then get a lil more then 180 degrees rotation before tight using a wratchet.

This is with a regrind cam (unkown core), and a set of larger size valves with the beehive springs from Dave Dalke and stock rockers.

The only thing Im thinking is that the combination of the longer chevy valves with the smaller base circle of the regrind comes close.

What do you all think?
 
Seriously. So I get the new heads on, try my stock pushrods....I hand tighten and then get a lil more then 180 degrees rotation before tight using a wratchet.

This is with a regrind cam (unkown core), and a set of larger size valves with the beehive springs from Dave Dalke and stock rockers.

The only thing Im thinking is that the combination of the longer chevy valves with the smaller base circle of the regrind comes close.

What do you all think?

are you saying the stocks are close..
 
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Do you have the factory pedestals? If so, they are M8x1.25.

That means every one rotation of the bolt, it is driven about .050" into the rocker stand. Half is obviously .025". You should target .050" of preload; therefore, it sounds like you need to get .050" longer pushrods and then put about .020" shims in it, too.

How many turns did you put into it, exactly? Just text me if you have questions, bro. It's OKAAAYYYY.
 
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Do you have the factory pedestals? If so, they are M8x1.25.

That means every one rotation of the bolt, it is driven about .050" into the rocker stand. Half is obviously .025". You should target .050" of preload; therefore, it sounds like you need to get .050" longer pushrods and then put about .020" shims in it, too.

How many turns did you put into it, exactly? Just text me if you have questions, bro. It's OKAAAYYYY.

That would not be correct son. .025 on the bolt will be a lot more than .025 at the lifter. Seems you are forgetting the RR in the equation.

The combination you have will work, but since the valves are a little taller, I suggest that geometry will be better if you shim the pedestals .060". If you do that, you'll need longer pushrods.

Before testing pushrods, you should be looking at geometry because shims determine geometry. Once you have the geometry you want, select a pushrod that will get you the correct preload. Off the top of my head I'd guess that most likely a 7.200 pushrod and some amount of shimming would be your best compromise.
 
I am using the stock rockers and got a little more then 180 degrees rotation. WHat I did was used a sharpie on the wear mark of the rocker to see where it sat on the valvetip. Seemed like it was on the mark. I will set my adjustable pushrod to 7.2 and play with the shims to see where that puts me though. Get this squared away by this

Thanks guys
 
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Damon,
The pushrods I got to work well with them were from a TPI Chevy 305/350, which I believe are right around 7.200. That was with stock ratio roller rockers.

DW
 
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