Pushrod Length & Preload
Pushrod Length & Preload I'd just like to verify that I've done the math correctly and selected the correct pushrods:
Note: I've edited this post since I measured incorrectly the first time
Intake:
6.800 + 11.125 * 0.050 = 7.35625
7.35625 + Preload = 0.0?? = 7.xxx
Exhaust:
6.800 + 11.25 * 0.050 = 7.3625
7.3625 + Preload = 0.0?? = 7.xxx
Question: What is the proper preload on Comp 850-16 lifters?
I am running TFS 215s and Harland Sharp Non Adjustable 1.7s.
Note: I've edited this post since I measured incorrectly the first time
Intake:
6.800 + 11.125 * 0.050 = 7.35625
7.35625 + Preload = 0.0?? = 7.xxx
Exhaust:
6.800 + 11.25 * 0.050 = 7.3625
7.3625 + Preload = 0.0?? = 7.xxx
Question: What is the proper preload on Comp 850-16 lifters?
I am running TFS 215s and Harland Sharp Non Adjustable 1.7s.
Last edited by Spd-Kilz; Jul 27, 2009 at 10:31 PM.
Sorry, I didn't specify.
I used the comp adjustable length checker. I made sure that I measured at the base circle of the camshaft. This is at zero lash. The rocker is still able to move, but ever so slightly - not enough to make a "tick" noise.
If that is what you mean by measuring.
I used the comp adjustable length checker. I made sure that I measured at the base circle of the camshaft. This is at zero lash. The rocker is still able to move, but ever so slightly - not enough to make a "tick" noise.
If that is what you mean by measuring.
Math is correct based on your measurement.
I don't know the preload on the lifters, have you contacted COMP?
I believe the newer TFS heads will run 3/8" pushrods. Have you considered those?
I don't know the preload on the lifters, have you contacted COMP?
I believe the newer TFS heads will run 3/8" pushrods. Have you considered those?
Are your valve stem heights 25 thousandths difference? Not sure why you would get a difference like that bewteen intake and exhuasts seems like a large margin to me. Maybe somebody can help with clearing that up.
It seemed strange to me as well. I do not know why there is such a large difference.
I read a post by Predator-Z that said these lifters run 0.060>0.100 preload. Keeping that in mind, would it be fine to run a set of 7.425 rods intake & exhaust? I'd end up with preloads of 0.0875 (intake) and 0.0625 (exhaust).
I read a post by Predator-Z that said these lifters run 0.060>0.100 preload. Keeping that in mind, would it be fine to run a set of 7.425 rods intake & exhaust? I'd end up with preloads of 0.0875 (intake) and 0.0625 (exhaust).
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If you're confident in your measurement then I'd go with the two different lengths. We typically stock both those lengths in 5/16" and can get you the 3/8" drop-shipped from the MFG in a matter of days for the same price. Let us know if we can help 
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Here is the proper preload for the 850-16 lifters directly off the instructions
Through various testing we have discovered that lifter preload should be set between .030” to
.040” or ½ to ¾ a turn of the wrench past zero for optimal performance.
.080 is way to much
Here is the link also
http://www.compcams.com/Technical/In.../COMP4-116.pdf
Through various testing we have discovered that lifter preload should be set between .030” to
.040” or ½ to ¾ a turn of the wrench past zero for optimal performance.
.080 is way to much
Here is the link also
http://www.compcams.com/Technical/In.../COMP4-116.pdf
Here is the proper preload for the 850-16 lifters directly off the instructions
Through various testing we have discovered that lifter preload should be set between .030” to
.040” or ½ to ¾ a turn of the wrench past zero for optimal performance.
.080 is way to much
Here is the link also
http://www.compcams.com/Technical/In.../COMP4-116.pdf
Through various testing we have discovered that lifter preload should be set between .030” to
.040” or ½ to ¾ a turn of the wrench past zero for optimal performance.
.080 is way to much
Here is the link also
http://www.compcams.com/Technical/In.../COMP4-116.pdf
So you have come across setups needing 2 different length pushrods? I'm just wondering how common this is to have 25 thousandths difference.
I should have updated this a while ago. I went back and re-checked (numerous times) and got a different measurement for the intake. This puts them within 0.00625".
The measurements with zero lash are: 7.35625 & 7.3625.
Now all that is left is to determine the preload.
The measurements with zero lash are: 7.35625 & 7.3625.
Now all that is left is to determine the preload.
Last edited by Spd-Kilz; Jul 27, 2009 at 10:33 PM.
That puts the intake at about .044" and the exhaust at about .038" (for those who don't want to grab a calculator).
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COMP - FAST - PACESETTER - DIAMOND RACING - EAGLE SPECIALTY PRODUCTS - CALLIES - COMETIC GASKETS
RAM CLUTCHES - MOSER ENGINEERING - KOOK'S HEADERS - ARP - GM BOLTS AND GASKETS - MSD - NGK
POWERBOND - ASP - AND MORE!
Largest Stocking Distributor of LS-x Engines / CHECK OUT OUR NEW WEBSITE!
COMP - FAST - PACESETTER - DIAMOND RACING - EAGLE SPECIALTY PRODUCTS - CALLIES - COMETIC GASKETS
RAM CLUTCHES - MOSER ENGINEERING - KOOK'S HEADERS - ARP - GM BOLTS AND GASKETS - MSD - NGK
POWERBOND - ASP - AND MORE!
