Getting my Heads and Cam Combo this week, need tips on pushrod measuring!
07-22-2012, 11:01 PM
#1
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Getting my Heads and Cam Combo this week, need tips on pushrod measuring! Well I am getting nearly 2,500 dollars worth of parts in for my 2002 Corvette C5. I'll list all the upgrades so that you guys will know what I am dealing with, then I will need help with pushrod lengths. I have a good idea of what to do, but there is so much damn conflicting arguments on LS1tech (do it that way, no do this, no your doing it wrong) that its kinda got my head in a daze, lol.
When I set the lash on the rockers arms of a Honda Civic, it was pretty darn simple. Though no pushrods were utilized in this valvetrain, you were basically eliminating all play at Top dead center. You wanted around .005 gap between the rocker arm and valve retainer. (But as I said, this a different application altogether)
So anyways, here is what I got coming.
PRC Stage 2.5 heads, milled to 11:5-1 compression ratio.
TSP 228R Camshaft, 112 LSA.
GM Multilayer steel head gaskets.
LS7 lifters.
LS2 timing chain.
Comp Performance Cam Trunion Upgrade.
Comp Performance Pushrod Measuring Tool.
From what I hear, the preload measurement for LS7 lifters is a different. .080 I believe. I thought I measured the pushrod with the no.1 piston at TDC, valves closed, but apparently I keep hearing that the cam is not at base center, so would someone help me with that.
If anybody has a good non-conflicting link, feel free to post it!
When I set the lash on the rockers arms of a Honda Civic, it was pretty darn simple. Though no pushrods were utilized in this valvetrain, you were basically eliminating all play at Top dead center. You wanted around .005 gap between the rocker arm and valve retainer. (But as I said, this a different application altogether)
So anyways, here is what I got coming.
PRC Stage 2.5 heads, milled to 11:5-1 compression ratio.
TSP 228R Camshaft, 112 LSA.
GM Multilayer steel head gaskets.
LS7 lifters.
LS2 timing chain.
Comp Performance Cam Trunion Upgrade.
Comp Performance Pushrod Measuring Tool.
From what I hear, the preload measurement for LS7 lifters is a different. .080 I believe. I thought I measured the pushrod with the no.1 piston at TDC, valves closed, but apparently I keep hearing that the cam is not at base center, so would someone help me with that.
If anybody has a good non-conflicting link, feel free to post it!
07-22-2012, 11:36 PM
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Staging Lane
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I have the adjustable comp pushrod tool.
Some people say the TDC is not on "base circle" I don't know. But what the other poster said appears to be right on the money, well it is how I would go about getting the measurements.
Base pushrod length say 6.80 -0.050 x number of turns =pushrod length then add lifter preload (say 0.80)
What is the lifter preload for LS7 lifters?
Some people say the TDC is not on "base circle" I don't know. But what the other poster said appears to be right on the money, well it is how I would go about getting the measurements.
Base pushrod length say 6.80 -0.050 x number of turns =pushrod length then add lifter preload (say 0.80)
What is the lifter preload for LS7 lifters?
07-23-2012, 04:30 AM
#5
Both lifters had better be on the base circle as both valves are closed. The intake has been closed about about 1/3 crank turn and the exhaust won't open for at least 1/3 turn. If they aren't on the base circle then cylinder pressure will bleed off.
I have seen some try to measure when the piston is at the top, but it was the exhaust stroke where there is overlap. That will be a problem.
I have seen some try to measure when the piston is at the top, but it was the exhaust stroke where there is overlap. That will be a problem.
07-23-2012, 08:30 AM
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Both lifters had better be on the base circle as both valves are closed. The intake has been closed about about 1/3 crank turn and the exhaust won't open for at least 1/3 turn. If they aren't on the base circle then cylinder pressure will bleed off.
I have seen some try to measure when the piston is at the top, but it was the exhaust stroke where there is overlap. That will be a problem.
I have seen some try to measure when the piston is at the top, but it was the exhaust stroke where there is overlap. That will be a problem.
