Originally Posted by Darth_V8r

Usually torque results in half a rotation on the bolt. That would mean your method 2 was lacking preload by a good 030. That would put you right in the range of your math method. To tell the difference between preload and torque, use a screwdriver handle to tighten the bolt instead of your ratchet. Or use a very mall ratchet so you can't get much torque on it. You'll feel it bottom out.

On the adjuster, I'm not a fan of the counting rotation method. I use calipers and measure the pushrods. I've never had the two not agree.

Originally Posted by Pantera EFI

HI ALL, this is good "tech" though NO ONE has added the AL block/head expansion value.

The block/head temperature effects the pushrod length specification.

I am sure all here will agree that a steel part will grow less than an aluminum part.
I too try for "center" plunger location, with no problems found.

The alloy, 319-T5, of the GM block has a different growth rate than a 356-T6 used in the RHS block.
The newer GM HP blocks get the 319-T7 for greater strength.

THUS, when checking the pushrod length, block temperature should be considered.

Lance

Originally Posted by I R Gunnr

Background:
Stock LQ4

Mild Cam
DUR @ .004" 272*/280*
DUR @ .050" 210*/218*
LIFT .551/.551
LSA 116*
2A

When I bought the cam, stock length 7.400" pushrods were spec'd and worked fantastically

Then rebuilt motor:

1 -Heads Milled .025 w/ .040 gasket

2. New LS7 lifters - but these are interchangeable part right? So shouldnt change pushrod length

So here is the confusions:

Method 1 - Using pushrod checker - zero lash at 8.5 turns = 7.225 + .070 preload = 7.300 pushrod

Method 2 - Counting turns on the bolt from zero lash. 1 1/8 turns from zero lash = preload of about .052, using .047 per turn. 7.325 Pushrod From this post

Method 3 - Math - I milled .025 from the heads and used a gasket that is .011 thinner. Factory .051 - .040 Cometic = .011. So .036" total less height from rocker arm to block (lifters).
Then how in the hell does a 7.300 or 7.325 pushrod make sense, using the other methods? I would think 7.400 - .036 -> 7.364, so a 7.350 or 7.375.


The motor is together and running, but has epic valve train noise using a 7.300" pushrod. I've been all over the valve train, rockers tight, bearings good, etc - all good.

Before milling the heads, the valve train was factory silent.
Since milling the heads sounds like a sewing machine.

Anyone share how much a mill changed their length?


I'm pretty sure my 7.300s are too short, but i'm back to lost on how much longer to go.

Originally Posted by kinglt-1

The ideal is to hit the middle range of the lifters travel. I thought LS7 had upwards of .190 on travel? and several folks have ran well over .080 pre load with good results. I personally would measure each valve and make sure none are under .070.

I am in a similar situation except I am running a morel 5315 with a travel of .140ish. Preload calls for .050 but I have several lifters in the .06x range because 3 valves measure .010-.015 lighter then the rest. Currently debating switching to a set of comp ultra pro adjustable rockers to get all valves the same and I am sure that will be worth a few ponies and a even more responsive engine down low.

It blows my mind after all these years somebody has not come up with a light weight adjustable roller tip rocker for LS....there is again the comp ultra pro but only offered in a 1.8 ratio which will work for some applications but most need or want a 1.7.