Milling Exhaust Surface

[Javabean]

Looking at a spare head, the surface of one of the exhaust flanges is pretty corroded. There's marginally enough flat surface left around it to get the gasket to provide a good seal for the header. I'm not confident though & marginal doesn't cut it, so since I'm going to mill the head for compression, thought I would have the exhaust surface milled as well. Any thoughts on how much can be taken off before the exhaust bolts bottom out? Or any other factors I should be aware of? I'm using Breslin locking bolts if it matters & the corrosion runs about 1/16" - 1/8" deep. I'd like to mill more than that if possible as the headers barely touch the bottom of the shock tower.

Thanks for any help,
Jay

 

[CZLN6]

Howdy Jay:

I can't offer any suggestions on how deep you can safely mill. I've only ever had a .010" to .020" clean-up cut done. I am curious as to why the exhaust flange surface is corroded so deeply? How is the rest of the head exterior surface?

1/8" is equal to .125". That's alot. Be sure to run a bottom tap into the bolt holes and pre-measure their depth before final assembly.

Adios, David

 

[Javabean]

Thanks for the reply David!

It's only the exhaust surface & flanges that appear to have taken a beating. In fact, the bolt hole for the rear exhaust is partially broken off at the top of the flange. Maybe bad casting? Maybe salt water in the air (the Ranchero it came out of was from SE Georgia)? Anyhow, I think 0.0625" would clean up most of the corrosion, fortunately the worst of it is on the very outside of the flange. I'm interested in taking more off to give the header more clearance from the shock tower. I'd hate to repair the nice jet hot coating Mike had put on it.

Thanks again,
Jay

 

[63Falcon200]

What year head you talking about?
I have a production 1980 head drawing at my house.
I had the angle changed on mine to clear the starter more.
Take a look at my web site... Let me know
if you need the bolt hole dimensions I can maybe scan the drawing
in certain areas.

 

[Javabean]

63Falcon,

I'm looking to have this done on a '69 flat top head. It looks like the bolt holes are 1" deep. THe header flange is 3/8" thick. Breslin bolts are 1" long, so I figure I should have enough romm to mill 1/8" off the surface.

I see you're in Detroit and checked out your website, nice Falcon & pics. Can I ask where you had your machine work done? My local guy knows his v8s, but doesn't have much experience with the the 6.

Thanks,
Jay

 

[63Falcon200]

I had the standard block and head machining done at Livernois motorsports.
The speacialtiy machining I had a Friend and McLaren enignes do for me.