977 and CompR - what is the correct preload for this setup??
Thread Starter
Launching!
Joined: Mar 2002
Posts: 223
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From: McKinney Texas
977 and CompR - what is the correct preload for this setup?? I know there has been alot of talk with different numbers, but what is the correct preload with this setup? I will not have adjustable rockers. I am having absolute speed set these heads up and another shop install the heads.
I need these to be as reliable as possible since this is my Daily Driver!!!
Thanks,
Crowley
I need these to be as reliable as possible since this is my Daily Driver!!!
Thanks,
Crowley
You will need .002-.004 preload with Comp "R"s, regardless. Jay told me that I would need 7.350" PRs and .030 shims. My AS heads are milled ~.025, and I too have Comp "R"s and Comp 977s. I am having a shop with experience in setting them (Comp "R"s and non-adjustable rocker arms) up do mine fwiw. Good luck, Shawn
I have a question or two. Those that say they are setting lifter preload at .002-.004, do you really think you can tell when you are at 0 preload just by turning the pushrod with your fingers and tightening the rocker bolt and not having a dial indicator directly reading the movement of the lifter piston which you cannot access with the heads on? Have you actually looked at a .002 or a .004 feeler gauge to see what a small amount that is?
Thats why someone who has successfully done this before is doing mine. 
I trust their experience and expertise. What other choices are available? Its this or ~$1100 in additional valvetrain ($250 valve cover spacers and $850 rockers).
Shawn
I trust their experience and expertise. What other choices are available? Its this or ~$1100 in additional valvetrain ($250 valve cover spacers and $850 rockers).Shawn
I agree, but the difference between stock lifter preload (I *think* ~.050) and the COMP "R" preload (.002-.004) should be able to be measured/estimated. My guess is that realistically <.010 or so is fine, which I think is attainable. What other options do you suggest or recommend? I, like others in this boat would like some other options, they just aren't there.
Shawn
Shawn
I have no suggestion. I just chuckle when people say they can set preload on a hydraulic lifter at .002-.004 using their fingers to feel for the starting point of 0 preload. I will say that understanding how a hydraulic lifter is put together that running the inner piston .002-.004 from the retaining clip that holds it in does not make sense from an engineering stand point.
