valve to cyl wall clearance with alum heads

[Glenwood]

I installed Edelbrock performer rpm heads on a stock 69 engine with comp cams .510 lift cam without issue. 2.14 intake valves. This engine came from a wrecked 69 super bee. Had only 125 miles on it.

was that a 383?

 

[pushrod]

Yes it was

 

[BSB67]

Has anyone installed aluminum heads on a stock bore 383 or 426W (4.25") without clearance issues?

I've been contemplating going to aluminum heads but I can't determine if I will have clearance issues with the cylinder walls.


Trick Flow 240 for example has a minimum bore size requirement of 4.32”. They have a large intake valve of 2.190 and an exhaust valve slightly bigger than stock at 1.76, whereas most of the other brand aluminum heads I've found have a 2.14 intake and a 1.81 ex.
I know that the max wedge blocks were notched for the large 1.88 exhaust valves. I don’t know how the cam lift values play into this tolerance, but my cam has lifts of .494I/.513E.


I’m interested in the promaxx 9440 which uses the same 2.14/1.81 valves but I’d hate to shell out a couple of grand (CAD) for heads & gaskets to find out they won’t work.

You will either need to disassemble the block, purchase the TF 240s and check. Not that big a deal really. The bottom line is no matter which aftermarket cylinder head you buy there will be a bunch of cylinder sticking to the combustion chamber so the block should be relieved for all of them. It is simply the exercise you go through if you really want a high-performance engine.

 

[Glenwood]

ok, so I spoke to Todd Marsh regarding sidewinder heads and he assured me that he has not had clearance issue installing these heads and valve sizes on stock bores of 4.25", although it has to be check when installing. So I ordered a set and am having him prep them with the correct valve springs. As luck would have it, I will be in NC next week on business and they will be ready to bring back with me!

So I pulled the 906's last night and as suspected, there's a little carbon build up on the pistons from running too rich, but nothing major. The cylinders look good but there is a slight carbon ring around the top.

Now this block was machined and assembled last summer using copper coat and steel shim head gaskets. How should I clean the surfaces, particularly to use cometic head gaskets with the new heads? The copper coat residue will come off with a little lacquer thinner or brake cleaner I guess, but after a quick test, it leaves a ghost line from the gaskets. Cometic gaskets call for a RA finish of 50 or near mirror finish according to their website and I'm not sure how to clean the surface to achieve this. Read lots of different techniques, but I don't want to ruin the machined surface with air tools or scrapers.

 

[miller]

Scotchbrite wheel. Just be careful not to get any of the fibers down in the holes.

 

[66Satellite47]

The CopperKote does come off easily with Brake Kleen. I would really want to hear real world experience with the need for the ultra fine finish recommended for the Cometic gaskets.