ws.6kid

I have a set of Comp "R"s part#875-16, a Trex cam, TSP 7.400 Hardened Pushrods, PRC Dual Valve Springs, GM performance graphite gaskets, .010 Milled 98 ported heads and stock rockers.

I have heard alot of horror stories about these lifters and I am a bit worried. Now what do I need to do step by step to have the correct preload?

I am assuming the normal 22ft lbs torque spec on the rocker bolts will not cut it?

BTW I have searched everywhere and have yet to find a guide on how to do this.

Thanks in advance...

Xtnct00WS6

iTrader: (8)

If you have stock or any other kinda of non adjustable rocker, you just need to get the right pushrod length to attain the right preload on the lifters.

ws.6kid

well how do i find out the right pushrod length for my setup?

Xtnct00WS6

iTrader: (8)

You'll probably be fine with 7.4. If you want to be sure, get a pushrod length checker from thunder racing. FWIW, I have milled 243's (.010 just like you), a Thunder Racing cam which is a .030??? smaller base circle and my preload was .080 which is great. I'm not sure if th etrex is .030, but I'm pretty sure my TR224 is. I have stock lifters so my preload spec might be slightly dif. than urs. You should look it up and see what's recommended for it and go from there.

Btw...ALWAYS torque the stock rockers to 22ft/lbs.

vettenuts

iTrader: (4)

The preload on the Comp R's is very small and with a small tolerance. You may need to measure each pushrod location to make it work. You are also going to have to get custom pushrods. Other option is adjustable rockers.

Slowhawk

iTrader: (12)

7.40 will be too long.Preload is ussually 1/8-1/4 turn.An adjustable pushrod is best to check it out with.Either that or buy a bunch of pushrods and try different sizes.

ws.6kid

how do i figure how my preload? Is there some kind of formula or something? How do I go about setting up the preload exactly?

Xtnct00WS6

iTrader: (8)

The preload is determined by how long your pushrod is. Check out this post about using the adjustable PR checker. It should clear some things up.

https://ls1tech.com/forums/showpost....05&postcount=4

ws.6kid

So I HAVE to use a PR checker?

There is no predetermined way of finding out what pushrod length I need by calculations?

How can I test to see if the pushrods I have right now are the correct size?

How can I determine the current preload I have right now with just the rocker bolts torqued to 22ft lbs?

This all seems pretty confusing, I am just worried cause I hear Comp R lifters need very little preload.

racecar

Call Comp and ask about preload. They will give you a number in thousandths of an inch. (They like .010, I like .030-.040 to make sure they don't make noise.) Use an adjustable pushrod. Set it short, and torque your rocker, then adjust the pushrod to 0 lash. Then remove the rocker and measure the pushrod length. Add the amount you want for preload and you will know what length your pushrods need to be. For me, it's worth paying the big bucks to get adjustable rockers and set each one right on. You will still need to have the right length pushrods, but you can adjust each rock to the precise preload. 1 turn, 1.5 or what ever works for you.

ws.6kid

Ok i measured what pushrods i need by using the comp cams pushrod length tool and came up with 7.343 at zero lash and with .010 of preload for the Comp R lifters my new pushrods should be 7.353. My question is does the pushrod size have to be exact or can I round this off to the nearest thousandth? Because I see that Thunder Racing offers 7.350 chromoly pushrods and it would be alot more convenient than ordering/waiting for some custom pushrods to be made.

If I have to get the exact size, what sponsor can I order some custom sized pushrods from?

ws.6kid

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WS6nJAX

iTrader: (207)

these are the same lifters i am using in my h/c swap. comp recommends .002-.004 pre-load, but the few people who i have spoken to said they all run around .010. comp also recommends the type r's only be used with adjustable rockers, but here again, the people i have spoken to also ran non-adj's set on .010 pre-load. i would try the 7.35's before i ordered a custom length. but thats just my opinion.

racecar

I would round it up to the next length longer. If you set them at .010 cold, your motor will sound like a worn out sewing machine after 30 minutes when it gets relly warmed up.
That's the experience I had with my 233/239 cam when I set it at .010, it sounded like solid lifters at .030 lash. I get tired of that noise real quick. The lifters were louder than the exhaust.

67Firebird455

iTrader: (27)

I have a set of these lifters also... and I know what you mean about a solid lifter (roller in my case) at .030... I had a cam that we ran .025/.028" lash, and it sounded like ***...

JMBLOWNWS6

iTrader: (17)

I know where you can get 7.350 in town

vettenuts

iTrader: (4)

How did you measure, end to end? That is overall length (OAL). Unfortunately the pushrods come in "gauge length", which isn't the same. So don't order pushrods until you determine how it was measured as the difference is OAL to Gauge Length is greater than the preload you are trying to achieve.

Did you use the Comp adjustable pushrod?

ws.6kid

Yes I used the comp cams adjustable pushrod. I started at the shortest setting which is 6.800 and did1/4 turns till there was zero lash with 22 ft lbs of torque. This was measured on the base circle of the cam.

kaos_

iTrader: (12)

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vettenuts

iTrader: (4)

OK, so you are taking the measurement from the number of turns and the little white lines, and not measuring with a vernier. The white lines will give you gauge length.