BB heads

Hi folks,
Getting older has some drawbacks. Like not making notes of something I read here (I think).
IIRC, I read someone discussed heads off a newer 454 that were 90cc factory. Even provided the casting numbers. I wish I had wrote that down, and even more wish I could find it myself without disturbing the brain trust. Seems like an easy way to bump compression up on a '79 stock 454. Not looking to do a major rebuild yet, just a cheater way to up compression. I suppose I could throw a blower on it and cross fingers...

Does this ring a bell with anyone? Thanks for looking, I appreciate it. Peel out!

I don’t have your answer but I do know that most later model heads are peanut ports and don’t flow well above 4k rpm.

I bet the person who posted this information was @Catbox

He's the only person I can think of that has swapped heads on his big block fairly recently

Could it be that the heads had larger combustion chambers to remove the quench areas, then using a dome pop-up piston to get the 90cc? Even the early heads with the bathtub shape combustion chamber were 98cc.

BB head info (click)

WZ7U said:

Hi folks,
Getting older has some drawbacks. Like not making notes of something I read here (I think).
IIRC, I read someone discussed heads off a newer 454 that were 90cc factory. Even provided the casting numbers. I wish I had wrote that down, and even more wish I could find it myself without disturbing the brain trust. Seems like an easy way to bump compression up on a '79 stock 454. Not looking to do a major rebuild yet, just a cheater way to up compression. I suppose I could throw a blower on it and cross fingers...

Does this ring a bell with anyone? Thanks for looking, I appreciate it. Peel out!

Click to expand...

Another link https://www.minuit10.net/EngineCode/chevy/BBChevyCylinderHead.htm

96 and up vortec gen 6 heads are 99cc chambers and bigger ports than the older tbi heads. Still could use some work on the entry to the valve area. They need more careful consideration when going on older block with the head gasket selection.

^ yep, that would probably be the one. Can't do much port work and practically no mods to the vane in the chamber. Folks have completely removed the swirl ramp in the intake port with minimal results. They're 100cc, typically.
I have a couple of sets of semi-closed chamber heads removed from Gen 6 engines. They need bigger valves, but otherwise look just like the old -063, -215 and -290 heads from back in the day. You might see if you can find a set of these - have your machinist and those around see if they have any. Clearly Gen 6 water passages but old school chambers. Probably a lot more productive than trying to the some of the L-29 heads to perform well.
But....if you're looking for fuel efficiency and good torque numbers and don't care about high performance, the L29's are some of the best.

The heads you are speaking of are the L-29 heads from a 1996 - 1999up 7.4L 454 engine.
NOT THE 8.1 heads at all, totally different engine.

These heads have a 100cc heart shaped chamber.
They are also not a peanut port head as those are reported to only have a 200 cc intake port, where the L-29's have a 230cc intake port. The fast burn chamber should also need less timing advance to be effective.

From an internet posts:
“Vortec, L29, The GM Performance Parts L29 Vortec Big Block Cylinder Head was used on 1997-99 pick-ups with 7.4L engines. They are the best kept secret of GM. The small 99cc combustion chambers raise compression by 1 full point from the stock 119cc heads. The large oval port design flows better than any factory oval port head. If you are looking for a good head to put on your tow rig to help you haul the load, then the L29 Vortec big block head will do the trick.”

"If you want performance above 4,500rpm than the 279 Vortec head is not a good choice but might be about the best choice for a torquey, lower rpm cruiser."

"BBC Vortec heads would fit a Mark IV block. They do. Use the Mark IV head gasket."

I have not yet had the time to switch my peanut ports out for one of the two sets of L-29's I have in my garage. But from all the research I have found, doing so is going to get you much better compression and that should bring about 30-40 more horsepower over what it currently has.

Here are a few photos that I have of them for reference....