How do I find the right push rod length for my 383 LT1?
04-30-2005, 04:05 AM
#1
How do I find the right push rod length for my 383 LT1? Hi , I have a 383 with AFR heads , a 235/245, .585in, .595ex. LSA 112+4, and 54cc, on the heads. Do you think that I need a different lengh push rod? Or should I just use the stock lenght rod?
Thanks,
Roger
Thanks,
Roger
04-30-2005, 04:30 PM
#2
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You can find a detailed process online, but you check pushrod length by marking the top of the valvestem tip with a sharpie marker. Go ahead and do both valves for cylinder #1. Install your factory-length pushrods, install the rocker arms and adjust valve lash as usual.
Turn over the engine several times by hand, then pull the rockers. Check the wear pattern left on the valvestem tip. It should be centered (perhaps a little toward the intake-side of the head), and hopefully fairly thin.
If it is too far off to one side, then you're going to have to purchase an adjustable pushrod length checker tool, and repeat the process until you get the desired wear pattern. Measure the checker-tool's length when the proper wear pattern is achieved, and order the correct length pushrods...
Again, that's the 'Reader's Digest' version -- I'm sure you can find it explained far better online -- such as Comp's website...
Turn over the engine several times by hand, then pull the rockers. Check the wear pattern left on the valvestem tip. It should be centered (perhaps a little toward the intake-side of the head), and hopefully fairly thin.
If it is too far off to one side, then you're going to have to purchase an adjustable pushrod length checker tool, and repeat the process until you get the desired wear pattern. Measure the checker-tool's length when the proper wear pattern is achieved, and order the correct length pushrods...
Again, that's the 'Reader's Digest' version -- I'm sure you can find it explained far better online -- such as Comp's website...
Last edited by Alex94TAGT; 04-30-2005 at 04:39 PM.
04-30-2005, 04:35 PM
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04-30-2005, 05:32 PM
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There's far more than just 'camshaft base circle size' that can affect valvetrain geometry. 
Straight from the first link I posted:
• block deck height
• head deck height
• head stud boss height
• rocker arm brand/design
• lifter design/brand/pushrod seat height
• valve stem length
Any, or all, of these things can affect valvetrain geometry. He just finished a 383 stroker buildup with new heads. It definitely needs to be checked, physically.
Straight from the first link I posted:• block deck height
• head deck height
• head stud boss height
• rocker arm brand/design
• lifter design/brand/pushrod seat height
• valve stem length
Any, or all, of these things can affect valvetrain geometry. He just finished a 383 stroker buildup with new heads. It definitely needs to be checked, physically.
