Ferocity02

iTrader: (59)

I bought some 799 heads new on eBay a couple months ago, had WCCH mill them 0.022, and I have put about 600 miles on them since. I took them off last night to swap the lifters and springs because I had some annoying lifter tapping on the driver side. On this head I noticed that two of the exhaust valves are 1.55" and two are 1.59". The other head has all 1.59". I think these heads are supposed to have 1.55" exhaust valves. I also measured how far the valve stems stick out of the head and there is a 0.03" spread in the stem height.

What the heck is going on here??? Can I run it as is? This is my daily driver and was hoping to have it buttoned back up tomorrow. I don't really have time to get new heads or valves, or have machine work done. I'm leaning towards just using them as is. There was no obvious issues during the the first 600 miles (unless this is causing the tapping noise which I don't think it is). I may have to use some different length pushrods to get the preload correct with the varying stem heights.

This is what I get for buying heads on eBay, even though they were new

Preston129

iTrader: (3)

I would worry about how well they seal against the valve seats (assuming they were all cut for 1.55" valves).

Ferocity02

iTrader: (59)

Yes I spoke with wcch today and found out that they are indeed cut for 1.55, that's why the stem heights were so different, the 1.59s don't sit deep enough. They are overnighting me a set of 1.55 valves, talk about service!

2000chevysilverado

iTrader: (11)

That close of a measurent most people would have missed

Ferocity02

iTrader: (59)

Yup, I'm surprised I spotted the difference.

stock48

iTrader: (16)

It's possible that could have been causing your lifters to be noisy if the height was off.

Ferocity02

iTrader: (59)

A few weeks ago went through and measured the preload on each lifter with a dial indicator and ended up using longer pushrods on 5 of the 8 exhaust valves, presumably the ones that were LS3 valves. So the preload was good on all of the lifters despite the difference in stem heights. Here are the preload results with all 7.325" pushrods:

Intake Lifters:
Cylinder Preload
1......... 0.075
2......... 0.083
3......... 0.081
4......... 0.086
5......... 0.084
6......... 0.082
7......... 0.081
8......... 0.078

Exhaust Lifters:
Cylinder Preload
1......... 0.079
2......... 0.067
3......... 0.080
4......... 0.069
5......... 0.066
6......... 0.071
7......... 0.059
8......... 0.075

Cylinders 1 and 3 had the correct exhaust valves, the others were LS3 valves. Also found these marks on the cylinder walls of 5 and 7. Looks like the marks shouldnt affect anything though, they are just above where the rings reach. I filed down the high spots lightly. I could barely fell it with my fingernail, probably only a couple thousandths deep.

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