Colder2012

Hello, his is my first post on this site, I have a couple questions about inconsistencies with my lifter preload. My application is as follows:

L76 6.0 truck motor, stock bottom end, 218/226 629/603 113+3 cam, ls7 lifters, 660 lift double valve springs, stock rockers with trunion upgrade, 7.4 pushrods, l92 heads milled .010, stock l92 head gaskets, stock valves.

I checked my lifter preload on cylinders 2, 4, 6, 8 with a pushrod length checker and this is the preload values that I came up with.

Cylinder 2 - Exhaust=.100 Intake=.075
Cylinder 4 - Exhaust=.100 Intake=.0875
Cylinder 6 - Exhaust=.094 Intake=.060
Cylinder 8 - Exhaust=.112 Intake=.075

I haven't had a chance to check cylinders 1, 3, 5, and 7, I will check them after work. My main question is, why is there such a large gap between exhaust valves on cylinders 6 and 8 and intake valves on cylinders 4 and 6? I plan to get some 7.375 pushrods for the exhaust valves, unless y'all would recommend going with custom push rods from Manton. Thanks for the help.

Darth_V8r

iTrader: (4)

what you're seeing is relatively normal. This is why I check all 16 valves, not just cylinder 1 and 2 like most. After you're done getting measurements, when you order, the pushrods will be +/- .005 from what you specify, so group them together. You likely end up with 11 at one length, 3 at another, and two "bastard" lengths.

Colder2012

Ok thanks. Would you recommend leaving the 7.4's on the intake side and put the 7.375's on the exhaust side or would I be better off going with 7.375's on the intake and 7.350's on the exhaust?

Darth_V8r

iTrader: (4)

I'd leave 7.4 on the intake side and go 7.375 on the exhaust side, assuming LS7 lifters

Colder2012

Ok that's what I was planning on doing, just wanted a second set of eyes on it. Would you think I would be good to drive it with the 7.4's in it until my other pushrods come in? I do hear a slight lifter tick on the #8 exhaust lifter. I don't know if that's due to too much preload or a problem with the lifter.

Darth_V8r

iTrader: (4)

If it were my car, I'd wait to drive it. Last thing you need to do is collapse a lifter. It might be fine if you baby it, but that would only be a guess. Not running it is a safe decision.

Colder2012

Ok thanks, I appreciate the input.

badazz81z28

iTrader: (6)

How are you getting measured pre-load? You should be checking with the push rod checker to measure for zero lash.

Once you do the that's, add the amount of preload you desire to that length for ordering. What is the longest and shortest measurement?