[jim_howard_pdx]

Hey Kevin, this message is primarily for you. On those Yates heads you are running, you must have custom headers to make these NASCAR heads fit in your Mustang.

You said the gaskets would only survive a single pass but that has not been my experience with the Yates head.

Take your header to a shop and have them surface the bead so it is 100 percent square and flat to the overall flange. It also makes for a slightly wider mating flange and allows you to add additional clamp force without over torquing the gasket material.

Most headers come with a quarter inch flange stock, then the primary tubes are interior welded to the flange plate, then they surface these weld beads to create the mating surface of the header.

I have all my custom header pipes welded on 5/16 steel flanges. I like to get the flange plate from the shop, and do my modifications first. I drill the holes extra wide, and I chamfer the inside edge that mates to the head.

Then I have the flange heat treated. Then I let the guys weld on the primary tubes. Then I check their surfacing and the quality of their mating surface. Get them bead blasted and then ceramic coated.

I demand 5/16 plate steel because some of the mild steel 1/4 inch flange material was so soft that I could bend it and form it without much effort. The header guys will say that this is so you can individually torque each tube.

This is total nonsense. The gasket makes the seal, not the flange. A soft bendable flange will not hold up to high torque launches. Make sure the flange stock is hard and SOLID.

Another reason to harden the flange plate is so they will be prestressed to enhance their expansion and contraction rates to better match the thinner tube material.

This would be overkill for 99% of the guys on this site. But Yates Heads are not stock, are not a street design, and are definitely in the 1% class where attention to detail is demanded.

Kevin, I hope this helps.