Im in the middle of rebuilding my motor after my head and cam upgrade. Im at the point now where ill need to use the Comp Cam push rod length checker to figure out what length push rods ill need.

My question is this, can i accurately measure what length push rod I need with the this Comp Cam peice while my my Comp Cam 977 springs are installed on my heads? My concern is that my hydrolic lifters will bleed down while turning the motor under the pressure of my 977 springs and alter my reading on which lengnth push rod i need. Maybe i should install one of my stock springs for this test?

 

You should either

A) use a solid lifter, or

B) buy a special low pressure spring designed for checking pushrod length using a hydraulic lifter

 

Thanks for the reply. I heard there is away to modify the stock hydrolic lifter to make it in effect a solid lifter. How is that done?

 

you basically have to take the plunger end of the lifter apart and figure a way to make it solid (putting something in there) and reinstalling the end cap. Basically you want to remove the spring part of it and make it solid. (use an extra!) then keep it for a future time.

 

Yawp.

I bought one LS7 lifter and made it a solid and keep it in my toolbox for that reason. I took all the parts out of it and used a small piece of all-thread that fit in the body and slowly sanded it down until it was the same length of the plunger, then reassembled it. Works perfect.

Or you COULD just disassemble one lifter and make it a solid temporarily, check for length, then reassemble it and use it.

 

Thanks for the help, i just took apart one of my lifters and it looks like i can reassemble it with metal washers in place of the spring. Ill see what i can figure out and post the results to get a general idea if i did it correctly

 

ok, took apart my lifter and stuffed it with washers untilthe plunger was fully extended. I called Comp Cams and what they told me wasthat i could use my converted hydro lifter but that i would have to add .040 tomy final measurement to compensate for the plunger travel associated and commonwith hydraulic lifters. If i would have stayed with the measurement i got withmy converted hydraulic/solid lifter with out adding the .040 i would have endedup with a push rod that is too short. So after all this i came up with ameasurement of 7.075" adding .040 gets me 7.115. The benefit of having a hydrauliclifter set up is that there is a little wiggle room i can work with so whiletalking to Comp they suggested I go with a 7.100 push rod which gives me andadditional .015 buffer as far as PTV clearance is concerned.