Early heads on later block
 

I picked up a ‘70 400 engine with a Weiand 671 blower on Weiand WP 671 manifold and ‘59 531395 heads. It was supposedly fresh and ready to run but I saw enough mismatched bolts to warrant a tear down. It looks like there was some serious porting done on these heads with the intakes measuring 1.23 x 2.22. Looks like some chamber grinding done, I’ll have to check CCs and dished pistons. It has oil through push rods and aftermarket roller rockers. I’m looking for information on what else I need to check and how to set up cooling. Is this even a good idea to go forward with? Building a ‘56 Chieftain gasser that this would look awesome in but I also want some reliability.

Oh man. That looks killer.

I would clay the pistons with the head gaskets off and see how much valve clearance to piston relief you actually have with that set of parts. Modern heads/pistons have a 14 degree valve relief angle and early pistons have a sharper 17 degree angle based on memory. How much lift does the camshaft have?

Tom V.

There are many very important things is confirm long before fretting about cooling!

1) that the valve notches in those pistons match the valve inclination angle of those 59 heads.

They look like they do since they are so removed from the center of the piston,

2) with the dish milled into those pistons you need to find out how much thickness is left in the tops and if that’s enough meat to live with the amount of boost your likely to ever run.

3) what rods are in the motor.

4) what valve springs are on the heads and if the intake valve spring has been set up to still be able to close with the max boost you ever intend to run.

For example, if your intake valve size is 2.02” that on average makes for 2.73 sq in of valve surface area. With just running 10 lbs of boost you will need 30 more psi of seat pressure then if the motor was not supercharged.

I would also want to know what brand bearings are in the motor and the clearance’s.

I would want to know how much valve to piston clearance I have without a head gasket in place.

I would want to know what type of steel the exh valves are made of.

I would want to know if the two compression rings where Moly face or not.

I would get a flow test done on the heads to determine there intake to exh ratio.
Also from your photo’s I can’t tell if the heads have the needed push rod guide plates installed?

I would also drill the extra cooling holes in the center deck area of the 400 block to match the head gasket and then opposite those holes drill the head gasket and then of course the block deck and the heads, so 4 holes total are added for better Cooling of the center exh port area can be had.

In short you need to dive into this with the frame of mind that the motor was built by a idiot until proved otherwise!

I was told it was a RAIV cam which if that’s the case would be .470 with the 1.5 rockers.
I will check clearance for sure and seek advice on the right cam to use. Guy told me it was set up for street use but top end came off of a drag car. My use will be primarily drag.
Thanks,
Tom

It has Eagle rods with ARP bolts and billet 4 bolt center main caps. I’m going to completely disassemble and have it checked including adding main studs. I was told it was set up for low boost about 5 psi. It does not have guide plates and I’m not sure if these rocker studs are even threaded. Or pressed in. Thank you for taking the time to give such a detailed response. I will update when I know more.
Tom

WITH ANY KIND OF PERFORMANCE CAMSHAFT, threaded is the way to go but,
I have seen several of the early heads where the boss was drilled from the side and a retention "pin" was installed thru the boss and into the stud.

That weakens both the boss and the stud.

Drilled, Tapped, and Threaded is a lot better way to go.

Tom V.

I saw a post about Paul Spotts screw-in stud conversion and my studs appear to match those he advertises. That would be a good start.

Definitely a cool build. Any pictures of the car?

Kevin

Here is with mock-up engine. Have a 461, e-head build in progress.

Since no one else asked....What is the casting number of the block?

Nice car!!!

Cool engine, looks like someone got a lot of the correct parts!

Are those steel shim head gaskets?

It’s 9799914 stamped code of YD. yes they are steel shim gaskets sprayed with copper. It looks like they planned the build out well then cheaped out on the assembly with mismatched head and main bolts just to sell it.
Thanks

Valve inclination on early heads was 20 degrees- up through '66, I believe.

The '59 heads guide the pushrods via holes in the heads. No guide plates needed; in fact they would conflict.

I'm a little confused by those chambers. '59 heads still had bathtub chambers. So, as a minimum, someone has milled away one side of the bathtubs. Which is somewhat likely, since that's the first thing Mickey Thompson did to any Pontiac heads back in the day, and many people followed his example (photo is a modified chamber of the '58 heads in my GMC).

Jack,
Thank you for all of the information. I wish I knew the history of the heads. I was told that the top end came off of an old gasser from California by the machine shop on the east coast that set-up the short block.

While on the subject of those heads the clearance between the two valves looks scary to me , how much is there when you measure it?

Those modified chambers due to the valve inclination angle look like a combination of SBC on the shallow side and a bit of 1968 and up on the plug side.

Rocket studs look to be screw in....someone must have tapped them.


GTO George

On this head the clearance between the valves is .021 - .023. The intakes are 2.00 dia. and exh 1.60

You are correct, the info I had from another forum was wrong.
Also B-Man did a nice thread where is says the angle is 20 degrees on the early heads.

But I found a Pontiac head cutaway picture and measured the angle with a accurate protractor and the angle on this 1959 head in the picture WAS 20 degrees.
Here is the link I found, hope it works 1959%20389%20Valve%20Stem%20Vent%20Diagram.webp
(I guess not but the title says it all.

Tom V.