Looking for a little info concerning push rod length. Assembling a 383 sbc that has had both the heads (AFR) and block resurfaced. How much was taken off I am not completely sure of but I do know it was a minimal resurface cut. I am also using a very thing gasket, FelPro 1094 at 0.015" compressed thickness. The last kicker is that I will be running a retrofit hydraulic roller cam with retrofit hydraulic roller lifters. Now these lifters are higher than the hydraulic flat tappets so I have read that the use of a shorter pushrod is mandatory. Also the fact that I have had both the block and head resurfaced and running a thin head gasket would mean I would need a shorter pushrod yet. I will most likely end up buying an adjustable pushrod to verify proper pushrod length, I just don't know what numbers I will be looking at and which adjustable pushrod I will need?
If the lifters are the same as the OEM hydraulic rollers, you'll be in the 7.2" range. IIRC most others are in the 7.3" range. But Crane uses very short p-rods for some of their hydraulic roller lifters and cams (just over 7.00").
If you know the brand of the lifters you can research it from that, or by measuring the distance between the p-rod body and rocker arm, then adding the depths of the cups. This will get you a ballpark figure to work with to make a tool.
Other things that can effect p-rod length is the valve length and cam base circle diameter, so you will need to mock it up once you get a ballpark figure to work from. A couple pages that will help:
• Adjusting hydraulic lifters
• Valve train points to check
• Valve train geometry
• Valve spring installed height
Click on image for details on making an adjustable pushrod:
Other homemade pushrod length checking tools at HomemadeTools.net
I got a set form amazon had both sizes of adjustables and was very cheap. Dont buy really expensive ones you will use it once and shelf it so go cheap. they all work the same. I think crane or comp both make a pretty cheap one.
Crappy thing is they make them right outside the size you need. one is 7.2 the other is 7.2 and above. Not sure why they dont make one that is 6.5 to 7.5 but i purchased two so maybe thats the reason.
This adjustable pushrod checker should get you the correct length pushrods. COMP Cams Hi-Tech Pushrod Length Checking Tools 7702-1 - SummitRacing.com. The stock flat tappet pushrods are 7.800". OEM roller cam uses 7.200" pushrod. Retro roller cam uses 7.300" pushrods. Most aftermarket heads use +.100" longer pushrods. This pushrod checker is 6.800" - 7.800" so it covers them all.
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