Valves recessed to far bad?

[ah1988ford]

2 of the intakes are under too much by 4 thousands and same with exaust somtsomet I should be worried about?

 

[Macrobb]

Too much by .004? Don't worry about it. .004 too little(less clearance)? Worry about it.

 

[jaluhn83]

Wouldn't be too worried either way. Too much reseccion (most likely the case) will decrease the effective CR, but probably not enough to make a difference, and even if it does, lower CR is good if you're running a turbo anyway.

Too little could reduce valve/piston clearance, but again I don't think it's so tight where 0.004" over will matter unless you've got a different cam.

 

[Macrobb]

Yes, it is that tight, even with a stock cam. I had a rebuilt engine; one side was around .010" under spec, nice imprint of the valves on the pistons(*all* of them). The other head was within spec, no marks at all.

 

[onetonjohn]

Disclaimer: Not a machinist specializing in IDI.

That said, from a layman's perspective, .004 inch is the thickness of a couple sheets of paper. If things were this tight, wouldn't carbon buildup be an issue?

 

[typ4]

Yes.
And I have seen 2 ****** engines that have valve marks in the pistons upon teardown. they are that close.
I sink them to the deep side of spec.

 

[typ4]

And I thought this question was already covered?