Thanks for all the help - this is my first big block to build and I'm finding out that they are alot more expensive and harder to find parts for around here (West TN). Is it true that I'll need a 119cc combustion chamber since I am running the 11:1 dome top pistons - to have enough clearance so the valves and pistons don't hit? Which BB heads were better - the oval or the rectangle ports? I really appreciate everyones help - I'm trying to get a grasp on all the BB Head info. I would love to buy a new set of aluminum heads - but I have a baby due in Feb and a couple other car projects going, so I'm tryin to watch my funds, especially since this is not a car I'm going to sell.

By the sound of the engine your building I really dont think your going to have a valve to piston issue but you need to watch dome style with a closed chamber head, can have some contact if wrong, send me your piston number and I can tell you, A bbc is very easy to get power out of for a street car you dont need much to get 500hp out of them and can be done with minimal costs, good luck with your project and a HUGE congrats on the new one.

http://www.sdpc2000.com/faq/kbhowto.asp?mt_node=360
Some interesting reading for you.

The blocks might take the same gasket but the water holes in the gen 6 deck are smaller, and thus the mark 4 heads work.

Sounds like I need to recall about 2300 engines Literally and go back so school :( I think the question was will a 5 or 6 head work on a 4 block?? not a 4 head working on a 6 block.... I might be wrong but I thought that was the question...... :wow: I am not trying to get a flame war going on Im trying to help a person with a project with known facts and also years of every day experience building gen 5 and 6 engines

No flame war. I just was confused by what you said about the gen 6 block so I did some more digging. My point is that there are more differences between the gen 5 and 6 than what you listed. The biggest is the change in the deck, it looks nothing like the gen 5, and takes mark 4 heads.

My experience is that the problem is 4 heads on a 5 block, I think the other way, 5 or 6 heads on a 4 block has never come up as most of the late heads are junk. The heads I recommended, the ZZ 502 heads, are of the universal design you mentioned. I have a set of these bolted onto a 1970 454 with no coolant leaks.

I too am just trying to help out. If the guy who asked the question has a 79 vintage block, the ZZ502 heads with their 110CC chambers, universal deck, and large oval port design are an excellent choice, and at the price offered with matching manifold by the other guy, are a smoking deal.

The SD catalog you quoted is not all that correct as well the only 6 block with a fuel pump boss is the over the counter replacement service block that is why the water passages are smaller and fuel pump boss added gm made a block to sevice all the engines with that one. The production gen 5 and 6 454 vortech engines in trucks from 1991 to today in the 8.1 have not had a fuel pump boss the only ones I have with them are service replacements. the aftermarket industry has made added deck surface to the heads with a small water passage to fit 4 5 6 blocks the new gen alum heads from gm performance are just Edelbrocks with gmperformace on them. Good question who is the largest purchaser of engines from GM I might post that its a good question

The 99 burb 454 I have in the garage has the smaller coolant holes, no fuel pump boss.

The largest customer of GM engines is likely Mercury Marine.

correct mercury marine