Ill find out for sure what head gasket was on it tomm when Im back at the shop
Quote: The ones with the shallow machined areas around the main chambers are intended for 340 pistons like yours................
Was their a thread about this somewhere? Id like to know more, it sounds like these are the wrong heads then but it also sounds like they can be made to work with the correct head gasket.
I think like I mentioned that the valves hit the top of the pistons at some point, made VERY minor indentations, I can get a picture of this hopefully tomm.
Looking at your cleaned up pix of the head, your DON'T have the shallow circlular recesses in the heads. So these are Edlebrock PN 60779 and your 63 cc chamber volume measurements are spot on spec for this part. SO that is very good info to establish for working further.
Cudafever points out something important with asking about the head gaskets: Piston to head clearance and gasket thickness. First off, if these pistons are good, I would not even think of changing them. They are good strong pistons. So working with these pistons and these heads as is would be where I would head unless I was doing some sort of dedicated race engine.
Where the head gasket thickness comes into play is setting piston to head clearance. With the pistons at a max of .040" out of the deck, then a .055" thick head gasket (crushed thickness) will set the minimum piston to head clearance at .035". That is about as short as you want to go for a worry free clearance. That would mean you want to get .055" thick Cometic gaskets. They are not cheap but this is the cheapest OVERALL way to use these pistons and the heads as-is. You get the benefits of quench for detonation suppression too. .060" Thick head gaskets would be OK too, if you worried about this at 100k miles of wear....
BTW, those Felpro 8553PT head gaskets are standard out-of-the-box Felpro gaskets. Nominal crushed thickness is .051" but folks have found them to vary. Too tight for this engine unless you are on top of things.
Cudafever's CR numbers look to be a spot on: high 9's to 10.0. (I get 10.0.) This will be a good torquey place to be for your truck use. This is pretty much ideal for wide street use, IMHO.
The valves hitting the pistons is very likely the valve float as said. The out-of-the-box valve springs on the Edelbrocks are decent but have their limits like any other spring. Check the piston tops for cracks; they are very probably fine, and just clean off the bits of aluminum hanging off.
The Edelbrock valves are 2.02" intake (you can look that all up now that you know the head PN) and should be fine in those valve pockets for a lot of lift as has been said. We have a set of those heads on some similar KB pistons, and with a .500" cam lift and 6 degrees cam advance, there was way over .100" of valve to piston clearance. But for SURE, check the valve-to-piston clearance when you start to assemble things with the new cam.
AND, now that you know that the valves have kissed the pistons, you need o get the heads to a shop to check for bent valves. You can do a quick check yourself by setting a head on a bench upright and at such an angle so that the valve head is horizontal. Pour some alcohol into each port and look under to see if it leaks out. A straight valve and good seat contact won't leak any alcohol.
Cam position: The cam is pushed backwards by the pressure of the lifters on the lobes; the lobes have a slight slope on the surfaces that does this. This force holds the cam back and the back face of the cam sprocket on the block holds the cam's position steady.
BTW on the bore measurements: If you got .001" above the 4.100" bore, my point was that small errors in using the telescope gauge can make them look small. (And other errors with the telescope gauge can make them look larger!) So that is why you would like to get a bore gauge into this block. And as far as the piston measurements, the normal place to measure piston diameter is across the thrust faces ('vertical' as I think you are calling it in the bores), and so far up from the bottom of the piston skirt. I just can't recall on these TRW's how far up on the skirts to measure them. The most conservative is to measure their diameter 1" up from the bottom of the skirt.
As for ring side clearance; it is simple. Just insert a feeler gauge between the ring and the ring groove and see how much space there is between ring and groove. Make sure the ring and groove are clean (but I suspect you aren't going to find much gunk in this engine).
