Originally Posted by MILD THUNDER (Post 4516020)

You are first saying you are thinking of running a .018 shim gasket, or a .027 gasket, or a .037 gasket. My suggestion, is/was, to run a standard .039 or whatever felpro gasket. Readily available, cheap, work well, and available for your particular situation "gen 6 heads on mark IV block". Will this increase the quench a bit, yes. Will it matter? No. Will the drop in static matter? No. Will running .037" for piston to head clearance be ok? Should be. Might be. I'd rather have a little more room. BBC's typically work well in the .040-.060 range. Being it isn't a competition deal, why risk it? You're running fairly poor performing cylinder heads, that don't do much for combustion quality, or airflow anyway.

The GEN 5/6 blocks, have coolant holes at the front of the block. Those holes MUST be blocked by the gasket, or , water will run right up and out the intake manifold, never cooling the rear of the engine. Felpro has this figured out. The 1037 Fel pro gasket, 4.370 bore .039 thick, fits Mark IV, GEN 5, and Gen 6 blocks. Bascially, the GEN 5 and 6, have holes in the deck at front of the block, that simply aren't used. Ever. The Mark IV blocks, do not have these holes at that location, even though some of the old gaskets had a hole cut into them. There was no hole in the block, so it didnt matter. Now, If you put on of those gaskets, on a GEN 5 or 6, yes, you would have an issue.

Originally Posted by phragle (Post 4516045)

http://www.jegs.com/p/Chevrolet-Perf...86gRoCHjDw_wcB


THere IS an 8.0 block, its a tall deck...

Originally Posted by Lee (Post 4516061)

Lets see some more pics of that Camaro.

Originally Posted by MILD THUNDER (Post 4516076)

Thats a Mark IV block in the picture?

Originally Posted by HawkX66 (Post 4516078)

No. This one isn't a Mk IV. It's all Gen VI.

Originally Posted by MILD THUNDER (Post 4516080)

ok, for whatever reason, all this MARK IV talk, i assumed you stated you had a Mark IV block.

Anyhow, those heads you have, are standard GM rectangle port heads, that were designed in the 1960's. They havent changed much of anything to the design since then. Their combustion chamber design, and exhaust port, are lackluster by todays standards in bbc performance aftermarket heads. They were the standard heads on the 502 and 454/420HP crate engines, and everything from a 365HP 454 magnum mercruiser, to a 800sc supercharged 572 Mercruiser. I am pretty sure, they have 3/8 rocker stud bosses, unlike most earlier versions, that had the 7/16 holes.

How close to cutting into the intake valve seat did they get when milling to 110cc?

Originally Posted by MILD THUNDER (Post 4516080)

Thats a cool engine GM came out with, for towing applications. 4.25 forged crank, vortec heads, etc. Pretty much a big brother to the old 454 L29 Vortec engines, like I have in my 1997 dually, and a bigger version of the old "tall deck" 427T engines.

Originally Posted by MILD THUNDER (Post 4516048)

I have never, seen a MARK 4 "8.0" liter block.

Phroogly, that engine you posted , is not a Mark IV block .

Originally Posted by phragle (Post 4516089)

Novody ever said anything about a mk4 block. THere was mention of going from a gen6 to a mk4 cam and difference betwee gen 6 and mk headgaskets and cooling.