young olds

Im thinking about getting my heads milled on the exhaust side to bring the divider flush. It looks like it will have to go quite a bit, anyone have a measurement of how far to go? And does it cause any problem with bolt hole depth or the freeze plugs?

Oldsmaniac

Some heads have a center divider recessed too far to mill flush. I believe for a BB these would be J heads not sure if there are any others. You can measure the amount of recess and then figure how much metal would need to come off. I think the ones I had done were B heads and there were no issues at all.

Smitty275

Usually take .180-.200" to get it flush with a small flat on it. It does increase flow a little but it also raises the roof of the exhaust port. So you either have to slot the bolt holes in your headers so you can raise them up a little or open the top of the header flange accordingly. You'll also need to trim the top of the gasket opening also.

J-(Chicago)

Also, if you have cheap headers, the pipe might hit the side of your oil pan, thus cooking your oil. Measure that clearance as well.

young olds

Thanks guys

Smitty275

I forgot to say that some headers will require multiple gaskets to make up for what is cut off. This includes ARH and Kooks/Dick Miller.

young olds

Thanks for the heads up

507OLDS

My heads are cut that way. The biggest issue I had was that having the flange milled that far back creates a shelf with the deck.

coppercutlass

Now I have never personally done this or had it done but if you did have the heads cut that way couldn't you just run those really thick remflex graphite header gaskets ?

507OLDS

I would have needed a spacer. I had to grind the bottom sides of the header flanges,to get them to clear the deck & bolt to the head.
Forget the W/Z manifolds,unless you use flanges for spacers.

Fun71

Would it be easier to weld up the divider?

507OLDS

You can make it thicker too.

young olds

can you weld up the area after machining has been done to the heads?

507OLDS

I would rather weld the center,to make it flush,instead of milling the surface back. My heads were old stock eliminator heads,that someone else had already milled. I think the center should be widened or thicker,to make a better transition into the header.

young olds

I meant will the other areas of the head need resurfaced after welding on The head?