Heads milled - mill intake?

[Bullitt]

So I tracked down the cause of my vacuum leak on my '67, mismatched head/intake angles.

Heads have been milled .020, but machine shop said the intake didn't have to be cut.

Anyways, either they're wrong or my intake has already been cut to a different angle.

Question is - what angle does the intake need to be cut to, or if I take it to a machine shop and tell them what the heads have been milled, will they know?

I imagine the best solution will be to bring the car to them so they can measure it......

Thanks ahead of time!

 

[Ronstang]

Jeff, I don't know the answer for you but I can give you someone to call tomorrow and get a real answer that you can rely on.

Owens Racing Engines
2308 North Austin Avenue
Pearland, TX 77581

Ask for Joe. He can tell you all you need to know and can do the work for you if you are willing to drive to Pearland. To give you an idea of how much I trust thes guys I won't go anywhere else and it is a 50 mile drive each way for me.

 

[65ShelbyClone]

Question is - what angle does the intake need to be cut to, or if I take it to a machine shop and tell them what the heads have been milled, will they know?

If the intake gasket surfaces are perpendicular to the deck, then the intake is 45 degrees on each side for a 90* V engine. Thing is, I don't know if this is the case with a sbf.

 

[headgrinder]

angle milling

You may have to have manifold milled to compensate for surfacing heads. .020
is at the edge of needing to have manifold milled but if deck was cut or heads were surfaced in the past the current .020 plus whatever was removed before
could make a requirement. For charts go to link below. Good luck

ttp://www.goodson.com/technical_support/tech_library/angle_milling.php

 

[Bullitt]

Great!! Thanks for the help. That chart is exactly what I need. Hopefully the intake hasn't already been cut....

Ronstang, that's perfect for me. My car and my "shop" are down in Pearland. Are they open on Saturdays by chance or only during the week?

 

[Ronstang]

Jeff, if you call Joe and make an appointment to drop off something on Saturday Joe will be more than glad to have someone meet you there. It is also likely that they will be working on the dyno on Saturday so there might be someone there already. Best to call and confirm.

 

[1320stang]

As I understand it, usually you don't want to touch the intake, other than to maybe slot the bolt holes a bit. When the heads get milled properly, they get milled on both the deck and intake surface, I'm guessing this is angle milled. I've been a draftsman for years and it doesn't make any sense to me, it seems like both need to be milled, but good machine shop guys say they only mill the head and not the intake, that way the intake will work on another engine with other heads.

 

[truck90278]

It all depends on how much you take off the deck surface of the head. As indicated in one of the other posts, there are published tables to determine how much to take off the manifold. If you were to mill the intake surface, then the "gap" between the manifold and head is increased - not what you want. When you mill the deck of the head, you are in effect lowering all the intake ports and bolt holes. When you mill the intake correctly, they will align again.

 

[1320stang]

Yeah, but if you take more off the intake side of the head deck, the angle between the heads is now less than 90 degrees in addition to being lower, so you'd have to mill the intake face as well and take more off the top of it to get the 90 degrees back.

As I said, I don't understand it, I'm just telling you what was told to me by people that know a heck of a lot more about it than I (i.e. Keith Craft, etc.) that you try not to mill the intake.

 

[Bullitt]

Well I found out tonight I got screwed on the intake. What sounded like a good deal turned out to not be. The intake has obviously been milled (bolt holes are slotted) and it doesn't fit at all with no gaskets. Front end fits flush and there's almost a tenth inch gap on both sides at the back (this is the intake to head surface).

I took another intake I had sitting around that has never been machined, fits perfectly flush.

You'd think an intake would be a fairly safe thing to buy used, but I guess I was wrong. Upside is I only have to get a new lower.......

Thanks for all the advice! When I get the lower in, I think I may take the car over to the machine shop Ron recommended so they can measure and make sure everything fits...

 

[Mach1steve]

when you mill the heads.....

I know because I did this.....
I don't know if it applies to all engines, but on my 351C, I milled the heads 30 thou and the intake 10 thou and it fit perfectly.
I was told by an expert on these engines that for every 30 thou you remove from the heads you take 10 thou from the intake sides.

I did what he said and didn't have any problems.
But I never tried the Intake on it before I milled it to see if really was necessary.
Mach1steve