I plan on building a 383 with the tpis/afr heads and ive got a few tech questions for those whove built some engines. tpis told me to 0 deck the block and use 15cc dished pistons with their 54cc afr heads and .029" head gasket to get 11-1 compression. they said this would be a safe combo with no detonation problems. I then went to a local machine shop and talked to the owner. he swore to me that with a 0 deck and .029" gasket, the pistons will hit the heads. he also told me that my cam, (tpis zz-409- 226I,226E @.050 .520",.520" lift), will create too much cylinder pressure and cause all kinds of detonation. I trust his opinion, but i know that he likes to talk people into buying his stuff. so who do you guys think is being more truthful, and i welcome any opinions of those who have experience with these heads.

 

All I can tell you from experience is that I put together a 355 for my truck with dished pistons(stock type keith black's) and wanted to raise the compression with thin (.015) head gastkets and the number one piston ended up hitting the vortec head causing it to sieze the rod bearing to the crank and spin it. I don't even think that the engine was decked all the way to zero but I will never do that again. It's not worth the increase of like .3 points in compression unless you want to risk having to pull apart the whole thing again to regrind the crank and put new rod bearings.

 

The heads are not the issue. They're flat where they meet the deck, no matter what heads they are. They don't stick down into the cyl. Ever.

The real issue is the combination of stroke, rod length, and piston "compression height", vs. the block's deck height. The best way to make certain of what you have is to dummy in the crank and one cyl, and measure the deck clearance. If the piston is at 0 or below the deck, then it isn't possible for it to hit the head, period; no matter whose heads you use, or what head gasket, or anything else.

That cam looks like a reasonable match for those heads and that size motor. IMHO 11:1 is a bit much for it though, even with aluminum heads. You should probably look to keep it down to 10.5:1 or so. Otherwise you'll have one of these motors that may run fine at the track at low block temps, but you can't run on the street with A/C and all that. (if it matters to you)

 

Maybe it's not possible at 0 deck but it's damn close and once everything is hot it will get even closer since the rods expand when hot.

 

I would run the deck height at .010"(in the hole) with the .029" gasket, that would give you a more detonation resistant quench area.

There are a lot more likely reasons for a spun rod bearing than a deck height issue.