bbc Questions

[elcaminoss84]

i am deciding to get a 454 from a mid 80's truck. i am think it has peanut heads. i know it would need to be rebuilt. would it be worth rebuilding or should i find something else? would 3872702 heads be good with a air gap intake and a performance cam or thumper cam and a 750 cfm carb mild bottom end ( 9.5-10.1 compression aftermarket rods stock or aftermarket crank) work for a street/strip combo? ideas or comment would be great since this would be my first bbc. thanks Spencer

 

[Malibuwagon80]

I have those same heads on a 461 in my wagon. It has a street roller and is about 12.1 comp. Its a closed chamber head. Those heads will work but if you're gonna rebuild the motor I would look for a set of open chamber oval ports. I have gotten my wagon to run 10.80's @121. with the closed chamber heads though.

 

[elcaminoss84]

whats the difference between open chambers and closed chamber heads? does one perform better than the other?

 

[Malibuwagon80]

There's a big difference. The open chamber allows alot better flame travel and complete combustion. All of you're aftermarket head designs are open chambered. If you're gonna go to the expense of buying a crank rods and pistons I would look around for a set of open chambered heads.

 

[elcaminoss84]

would porting and polishing closed chamber heads make then perform better or about the same as open chamber heads?

 

[abigda]

I've had good luck using smog oval port heads, they make good torque. The ones on my current engine, are port and polished with gasket matching, and Large stainless steel valve, which the machine shop had to machine recesses in the cylinder wall for clearance. Engines and absolute torque monster. I want to put aftermarker heads on it, but needed to go cost effective at the time.

 

[StrokedBBC]

The guy that does all my head work said the head casting #781 is the best oval port, mild pocket port, gasket match, 219 int./188 exh valves had my 79 Firebird with a mild 468ci. 3850lbs. with me on 275/60 Hoosier Quick Times best 11.77 and that's with a 2.07 60'.

 

[elcaminoss84]

the 702 heads i am getting for free and they have been ported and polished so it should be a good starter heads so i can atleast drive my malibu while my el camino is getting painted.

 

[Bar50]

The closed chamber heads work just fine till about 6000 or 6500 RPM. The closed chamber shrouds the valves, sorta' hinders flow when you spin the snot out of them. The trade off, well, you don't need a set of dome pistons to make decent compression. They work just fine.

GM went back to a similar casting to 'pep-up' the 454 found in SS trucks. Full size oval ports and a 96cc chamber to make 8.5 or 9.1 compression. Pump friendly and plenty of thrust. In big block chevys, compression makes the power curve climb, find a desktop dyno, CompCams used to offer a free one, try it out.

I have also used the closed chamber Vortec big block heads on flat top 454's. I have also pepped up some 454's with 702 and its mate was like a 215. We used to call them '65 396 heads, or thats what most of them were.

I am also a big fan of the 781 and 049 oval port heads, I usually went with 2.19 1.88 valves (buy new take outs from boat guys real cheap). But, with flat tops, then you gotta' angle mill them for compression, or buy dome pistons.

 

[Excelerater]

peanut ports = junk
closed chambers = junk

Dont waste your hard earned money - besides BBC are too nose heavy w steel heads
Save up for ALUM but if your gonna go steel you have a hand full of choices
Big Ovals (049/781s) or Rect OC (188s/990s).....but they are too heavy,70 lbs a peice LOL