mixing early/late BBC parts
 

Is it possible to use MkIV ('86 vintage) heads on a Gen.6 block? I thought I remembered reading that there is a head gasket that would allow this without any fluid leaks. Thanks for any help.

Re: mixing early/late BBC parts
 

That's an "iffy" situation. FelPro makes a few gaskets, you need to call their tech line or look at a catalog.

Re: mixing early/late BBC parts
 

Thanks Alan. I was pretty sure you would know and also respond.
Ken

Re: mixing early/late BBC parts
 

I know it can be done because I seen 502 blocks used to build 540's use aftermarket heads like Alan said
call fel pro tech line to get right gasket catalog has that info but is confusing so call them to verify.
Mike Taylor3601

Re: mixing early/late BBC parts
 

That is definately no problem. I built a 502 for a bracket/street driven car and used a GenVI block with early oval port, closed chamber heads. I can't recall what head gasket I used but I belive it was a GM gasket. That engine is still going. It never had any problem and has run in the 9's after it was transplanted from a street car into a racecar. I got the info for what I needed and bought some parts from one of the GM Performance parts dealers thru their catalog. Pace Chevrolet. Scoggin Dickey is another good source. Lots of good info in those catalogs..........

Re: mixing early/late BBC parts
 

Thanks for the help guys. I'm trying to come up with a viable engine for my dually. My grand experiment with Rectangle port heads was a bust, even with revs of 3 grand plus. I should have known better; just gettin' stupider with old age. I now realize why the diesels are the engine of choice. I just can't afford one.

Re: mixing early/late BBC parts
 

Ken, the hot setup is the old closed chamber oval port heads, or the Vortec heads. About 96 to 100cc chamber, and 2.19 intake valves with 1.88 exhaust valves. If you can get 10:1 compression it will work fine. My old 454 had about 9.5:1 and it really wasn't enough, even though I went down in cam to a 218/.520. An all steel flat bed truck, with steel wheels and no overdrive it would get 12-14 loaded or not, and pull 20K pounds with ease. With the air on. Of course, with Camaro headers, 3" pipes, and huge mufflers, it sounded a lot like a stock car on the Interstate. I think with 10:1 compression, overdrive, and fuel injection I could do better.

Re: mixing early/late BBC parts
 

Alan, thanks for the additional info. You've prompted a new batch of question's, if you don't mind answering them.
What gear ratio was your truck? My dually has 4.10's.
Did you use a 'stock' converter, or one for towing?
Your thoughts on stroking to 496. That would boost the compression ratio a little.
Best header tube size?
Did you stay with a Q-jet? Manifold?

This is an '86 C-30, so no OD. The engine is a low miles 454/425 crate. The Vortec heads you mentioned came out in '96 I believe, so they should be a direct bolt-on. I know the smart play would be to buy a late model diesel. But, since my wife recently lost her job (30+ years as an RN with the same hospital), the bucks just aren't there. Realistically, probably not for these engine mods either. We'll see.

I appreciate everybody's help.

Re: mixing early/late BBC parts
 

I think the gasket is a 1047 Fel Pro. Better check.. it's late & I'm at home, far away from any cataloges.... & my memory is getting, well just say a bunch of birthdays :~)

Re: mixing early/late BBC parts
 

I have a set of 215 oval port closed chamber heads for sale. I think the date code is in 67 sometime.