Machining a intake manifold gasket surface

[JeepsAndGuns]

Few years ago I put some diffrent heads on my engine. I did some mild port/polish work to them, had a 3 angle valve job, and also had them shaved a bit. If I remember correctly, I believe he said he shaved about .020 off them.
When I installed the intake, I just about couldnt get it back on, a couple of the bolts started, but a few wouldnt. After lots of fighting and cussing, I got them in and tightened. I had to remove the intake a couple years ago (forgot why) and it was another fight to get it back on.
Now I am getting ready to swap on my MPFI intake, and I dont want to have this problem again. I want to be able to just set it on and bolt it down. So, when I take it to a machine shop, how much should I have them take off the intake? .010? .020? .005?
I have no clue, anyone been through this before? As far as I know, the block has not been decked.

[FSJ Guy]

It's times like this when I wished I paid more attention to trigonometry.

I would think your machinist would know. But maybe not if they're not familiar with AMC motors. It would have to do with the angle of the heads as compared to horizontal. And then it would involve a sine or cosine operator I suspect. But what do I know. I dropped out of Calc III.

[EagleMark]

Well you took .020 off the head so it now sits lower. For the intake to match correctly you would need to take off .020. That does not take into account aftermarket head gaskets which can have different overall thickness when torqued.

Tell your machinist who decked the heads the problem you had, let him decide what to do with new intake.

[gregs78cam]

Really what we need to know is the angle of the intake flange relative to the head/block surface. With that I can figure out how much to take off. You may not need the material taken off the intake flange, but actually taken off the lip that seals against the valley.

[JeepsAndGuns]

Tell your machinist who decked the heads the problem you had, let him decide what to do with new intake.

Well the shop that did the head work, said they didnt have a way to put a intake into their decking machine. Or mabey they didnt have a way of holding it, one of thw two, I cant remember, its been so long. But taking it to him was the first thing I did when I had trouble getting the intake on. He told me I might have that problem, and I might have to have the intake shaved, so I assumed that ment he could do that, only to find out he couldnt. So that shop is probably out. I figure I would be better off going to a actual machine shop for the intake.

Greg, there was still a good gap at the ends of the valleys. Edelbrock say dont use the rubber seals, and use a thick bead of RTV. So thats what I have been doing.

[gregs78cam]

Ok, do you know the intake flange angle? Is this for the 401 AMC in your sig? If it is, and this pic is right.......
1754
http://www.jpmagazine.com/techarticles/engine/154_0412_amc_v_8_engine/viewall.html

then it looks to be pretty much 90*. If that is correct, and this is a 90*V8, then the flange would need 0.020" taken off each side, and your gap at the front/back of the manifold will close up 0.028", but that is just a rough guess.

[JeepsAndGuns]

Yes, its the AMC 401. And as far as I know, they are standard 90 degree V8's.
So I need to have the intake shaved the same ammount I had the heads shaved?

[gregs78cam]

thats what it looks like.

[JeepsAndGuns]

Now to make it to the machine shop before they close.
I get off at 4:30, they close at 5, and they are about 30 min drive away from where I work. :mad1: