Hey guys ive been working on my 383 blower motor and its time to determine my pushrod length. I know i need to use a pr length checker but i dont have one available and am not sure how to work it exactly. My cam has a 571 lift and my block has been zero decked in your opinion what length pr should i need?

 

won't know until you measure it.. DO NOT order pushrods before you measure for the length. You can probably get one at a local auto parts store.

 

how much were your heads milled if at all?

how much was taken off the block?

what ratio rocker are you running?

what headgasket are you running?

 

I don't believe anything was milled off my heads, im running 1.6 ration and im not too sure about the block itself. My headgasket .40 compressed thickness

 

The following is a method of verifying proper valve train geometry. After you have estimated the required pushrod length using a Pushrod Length Checker, use this method to verify that the valve train geometry is correct (using the rockers you are using in your engine):



1
The first step is to install a solid lifter and an adjustable pushrod. Mark the tip of the valve with a marker



2
Install your rocker arm and set it up with zero lash.



3
Rotate the crankshaft clockwise several times. Remove the rocker arm. The contact pattern of the rocker tip will be where the marker has been wiped away from the valve tip. The pattern should be centered on the valve tip, and as narrow as possible. If it is not, experiment with varying the pushrod length to yield the best pattern.



4
Pushrod Too Long: Notice how the pattern is wide, and shifted to the exhaust side of the valve tip.



5
Pushrod Too Short: Notice how the pattern is wide, and shifted to the intake side of the valve tip.



6
Pushrod Length Correct: Notice how the pattern is narrow and is centered on the valve tip.

There are pics to go with this info here . . . . .

http://ls1tech.com/forums/showthread.php?t=327734

look at post # 5.

This is an LS1 page so the info is for LS1's but the PR length checking procedure is for a SB Chevy/LT1.

Lloyd

 

Just find a stock length pushrod and use it to measure to get an idea of where you are at and then go from there. I actually found a stock length to be the correct length with my old motor even though the block was decked and heads milled.

 

OK, I have a stupid question. Where does one get a single solid lifter that has the exact dimensions as the hydraulic lifters that you are planning to use? For example, I am replacing my Comp lifters with the LS7 version.