pushrods

[gmhatr]

Ok this is what i'm doing I'm going to be putting a set of c5 heads on my 302 roller block. How do i determine what length of pushrod I will need beings this head uses a stud mount rocker? Or will the stock length be fine. I will probably be using a set of 1.7 roller rockers with this also. Thanks

[jonnyk]

The only way to know is to buy an adjustable length pushrod (one that works around the 6.25" mark) and mock it up with your head gasket, a solid lifter that is the same size as the lifters you are using, and then measure what length you need. Somebody on here may have the procedure...I can dig it up later if need be.

[RPM427]

How to check for pushrod length:

1.With the cam, crank and timing set installed, bring number 1 cylinder to top dead center on the compression stroke.
2.Install the two lifters that will be used for checking on the intake and exhaust lobes of the cam for number one cylinder (make sure they are solid).
3.Bolt the cylinder head on the block with no head gasket. (Do not torque the cylinder head, just make it snug).
4.Install the guide plate and rocker arm studs. Again do not torque the studs, just make it snug
5.As a starting point, adjust your checking pushrod to the same length recommended by cam manufacturer for the cam and lifter combination you are using.
6.Install the checking pushrods in the engine.
7.Take your black magic marker and color the tips of the intake and exhaust valves.
8.Install the intake and exhaust rockers and adjust the rockers to zero lash.
9.Rotate the engine over by hand several times.
10.Remove the rockers and note the contact pattern the rockers made on the tip of the valve.
11.If the pattern is centered on the valve tip, pushrod length is ok. If the pattern is wide to the exhaust side of the head, your pushrod length is too long. If the pattern is wide to the intake side of the head, the pushrod is to short.
12.If adjustments need to be made, remove the rockers, recolor the tips of the valves, lengthen or shorten the adjusting pushrods as needed, reinstall the rockers and rotate the engine over again by hand. Repeat the process until the desired pattern is achieved.
13.Once the desired pattern is achieved, remove the checking pushrods from the engine and measure them. Take that measurement and add the compressed thickness of the head gasket being used. The sum of this will be the correct pushrod length for your combination

Thats it! You can get a an adjustable pushrod through Summit Racing for a few bucks.