I have searched everything and read all that I could find about BBO Heads and cannot find the answer.. HELP Please

I have a 67 400E with 1965 A heads and want to know if the heads have the exhaust crossover ??

The engine is stock and runs fine, I do not want to tear into it just to find out this, but I would like to know for possible future mods to this engine.

Thanks,

Thirdcoast

 

As far as I know, all Olds heads have the exhaust crossovers. Only the later high performance engines (W-30, H/O) had one crossover blocked.

 

It has been said the A heads do not have the AIR bumps in the exhaust ports making for a bit better flow.

 

Yes, I agree with Oldsmaniac. Although I have come across a couple A heads with the AIR bumps, very much out of the ordinary. They do have the exhaust crossover but 65-68 had smaller openings than the later heads.

 

X3 guys

 

As noted, most A heads did not have A.I.R. bumps. These were apparently added late in the model year in anticipation of the looming CA emissions requirements for the 1966 model year.
The other thing to note about the A castings is that they use 3/8" studs with unique rocker trunnions. Those parts are not available today, so replacements can be problematic. You can use aftermarket roller rockers on 3/8 studs, but you still need to machine the pads on the heads to allow clearance for the pushrod guide plates.

 

Thanks everyone, that's what I needed to know..

Thirdcoast

 

For what it's worth, a 67 400 E had C heads, so one with A heads is not stock. Perhaps I misunderstood and you meant no work has been done on the engine other than the head swap.

 

Block off the crossover in the intake, not the heads. Easier to do, (weld in the iron plugs), and easier to machine out if it ever needs to be reversed. Dont fear the Olds iron intake. Thou its not light.
20 years on this intake paint.

 

I may or may not receive flack for this but regarding the use of "A" cylinder heads, the later style trunnions/pedestals can be used by drilling the bolt holes in the pedestal to accommodate a 3/8" bolt.