Nailhead guys: 401 heads on 322 block questions

I'm going to build a 322 this year or early next year for some racing. I want it to be tough as an anvil, not terribly trick or exotic, but strong too.

The 401 valves are bigger than 322 valves, and I'll go out on a limb and guess they flow a tad better than the 322 heads.

I've heard that putting the bigger valve heads on the 322 will kill compression. I need the engine to be somewhat high compression...9.5:1, maaaaybe 10:1, and I can knock it down with a thicker gasket when need be.

Can anyone tell me if the heads will in fact kill compression?
Will the bigger valves fit over a 4.030 bore?
Does anyone recall anyone making pistons for this conversion? I'm sure I'll need pistons made, but it'd get me heading in the right direction.

What am I missing?

-Brad

 

the stock intake will not fit the 401 heads. you can use 4 or 6 carb log manifold

 

does the intake not fit because of deck height? well just use 401 intake, the aftermarket kind(not neccesarilly log style, but anything tats a split manifold, someone makes some for the 401 that use weber's) if you got both just mock it up and see what u need

 

I was unaware that the heads would even go on. I guess I've only been messing with the 364/401/425's. But I think that it would be cheaper and more powerful to pick up a 364. I still have a soft spot for the middle child of the Nailhead family...

 

yeah, i didnt know they fit either, but same for me, ive always played with the bigger of the family.

im sure nowadays you can get any piston you want made, call egge.

jeff

 

I know there is a stroker cocktail using some off the shelf stuff. Pontiac rods and stock pistons. I need to dig that stuff up and build one...

 

I was under the impression that the bore spacing is the same, but the spread from side-to-side is different on the families because of deck height. As the deck gets taller up the "V", the heads get farther apart. That's why a 322 intake will work on a 364 if the bolt holes are wallowed out.

Class rules dictate the 322, but I believe I can sneak the bigger valve heads thru. Just trying to find out how to handle combustion chamber volume/compression.
-Brad

 

You can make a 322 intake fit if you oval out the bolt holes. THe later heads have larger intake runners/openings as well. You can open the intake ports to make them closer but not enough material to make a match. Won't be bad as the heads have the larger opening.

you might have to make the thermostat crossover a three piece to match the head spacing. I can get more details later.
I will have to dig out the old 322 block and take a piston out and see who made it. Probably won't happen until spring though.


The off the shelf stroker I beleive uses the 364 crank, pontiac rods and a 401-425 block. The 364 has a different thrust bearing location (ie maybe #4 vs #3 main bearing) than the 401-425. the 364 should give a 1/8" stroke I have heard. I have not done this one yet so I can't recall all the details or know for sure first hand exactly how well it works.

 

That sounds like the one...
And all I need are the Pontiac rods... so it should be pretty easy...

 

Make sure the Pontiac rods and buick pistons share the same size wrist pins. For some reason I am thinking they are different.

 

Last year, I picked up a '56 322 with 401 heads on it, with a stock '56 intake, and it all seemed to go together all right. The thermostat crossover was cut and spliced together with lengths of straight heater hose, though.

 

I need to find where I wrote everything down. I remember it sounding pretty easy. Everything was off the shelf parts. I just can't remember which pistons it said to use and which Pontiac rods... of course I just tore the hell out of the rear on my '57 with a slightly warm 425, broke the mount for the Jag rear, so maybe making big power is just gonna cost me more money...

 

What'd it have for pistons?

-Brad

 

That is just about how mine is setup. Mine has what looks to be BIG pop ups on the pistons, until you realize how big the chambers are.

 

If I recall correctly, you machine the Pontiac rods to accept Buick wrist pins.

as far as tearing the mounts you put in for the Jag rear, don't feel bad. I split a '56 Olds housing down the seams on both tubes with my 401. Ruined an otherwise perfectly good rear. I ended up using the brakes on my 57 olds rear and put the center section in a friends 55 Olds.
Even the 57 rear has a crack starting from the Ladder bar mount on the housing. About time to go through the rear again...

 

Jahns pistons, .125 oversize (which makes my 322 a 342). Like Dualquad55 says, they'd be 14:1 in any other engine, but nailheads have cavernous combustion chambers.

 

hey man, out of curiosity what kind of racing are you planning to do???