How to set Lifter Preload????
#1
TECH Apprentice
Thread Starter
Join Date: Jan 2004
Location: San Antonio, Texas
Posts: 380
Likes: 0
Received 0 Likes
on
0 Posts
How to set Lifter Preload for COMP R Lifters????
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...
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...
Last edited by ws.6kid; 07-22-2006 at 06:17 PM.
#4
TECH Fanatic
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.
Btw...ALWAYS torque the stock rockers to 22ft/lbs.
Trending Topics
#8
TECH Fanatic
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
https://ls1tech.com/forums/showpost....05&postcount=4
#9
TECH Apprentice
Thread Starter
Join Date: Jan 2004
Location: San Antonio, Texas
Posts: 380
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
#10
TECH Resident
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.
#11
TECH Apprentice
Thread Starter
Join Date: Jan 2004
Location: San Antonio, Texas
Posts: 380
Likes: 0
Received 0 Likes
on
0 Posts
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?
If I have to get the exact size, what sponsor can I order some custom sized pushrods from?
Last edited by ws.6kid; 07-31-2006 at 01:29 AM.
#13
Restricted User
iTrader: (207)
Join Date: Aug 2005
Location: jacksonville, fl.
Posts: 555
Likes: 0
Received 0 Likes
on
0 Posts
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.
#14
TECH Resident
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.
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.
#15
12 Second Club
iTrader: (27)
Originally Posted by 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.
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.
#17
TECH Senior Member
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?
Did you use the Comp adjustable pushrod?
#18
TECH Apprentice
Thread Starter
Join Date: Jan 2004
Location: San Antonio, Texas
Posts: 380
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by vettenuts
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?
Did you use the Comp adjustable pushrod?
#20
TECH Senior Member
iTrader: (4)
Originally Posted by 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.