Milling the intake is unnessesary when you can just mill the intake side of the head of angle mill the deck of the head. When you mill heads it is usually because it was a little warped or you want more compression. Why would you not make the head still work with any stock intake? FE intakes are too expensive to go cutting into. You can take a straight .020 off the bottom of the head or the top of the deck before you need to worry about removing any more material.
Yeah I've read that before. If you want to get more compression the best way to do it is to shave the deck of the block to the point where your pistons come up all the way to the top. Keep in mind this is using performance pistons that almost come all the way up anyway. This will ensure that you have optimum quench (least amount of space between the outsides of the pistons and the bottom of the head. It will allow you to get by with more compression per octane that way. 428CJ heads are hard to come by if you don't already have them. 390 heads can be fitted with 2.09/1.65 valves and can be ported to flow better than the CJ heads. I think anymore than 10.5:1 compression with Iron heads is going to give you possible problems for street purposes. Still would not mill the intake no matter what. Mill the deck, then the heads and then the intake sides of the heads. I'm not all sure about angle milling. Got to thinking about bolt angles afterwards and that's getting into a bunch of work.
Think of it this way, when the heads are milled the bolt holes for the intake drop toward the crank centerline. Unless the manifold bolt holes are reamed lower to accomodate this the manifold must sit lower. It can only go lower to a certain point before it will be in full contact of the head/manifold face and still not line up with bolt holes. If the bottom of the manifold and the sides are milled it can sit lower, line up with the bolt holes and still have the clearance on all three sides to run gaskets (head/manifold for both heads and the manifold to block clearance for the cork gaskets)
Sturz, your original thinking is correct. Milling an intake manifold is very much a no-no, or more like a not ever under any circumstances. 'Woody' has no clue what he is talking about. I have no idea where this intake milling idea came from, it is a great way to ruin a perfectly good intake. Your already milling one surface on the heads, why not do it right and mill the intake face of the cylinder heads the same amount ? If one mills the intake, it won't fit correctly with unmilled heads. Then when you stumble across a good deal on a pair new aluminum E-brock heads, you need a new manifold too, cause you wrecked yours. Very bad. As for the bottom of the intake, no problem. You should not be using the cork end seals anyway. Use a nice bead of RTV and it will fit fine and not leak. At the shop where I work we never use the cork gasket end seals, and our engines don't leak. We have some circle track customers who want their heads milled for more compression, and we have taken off .060 from the deck and the intake face of the head. everything fits fine with zero hassle. Rat- angle milling is something some of the chevy guys do for more compression and to stand the intake valves up straighter ( better breathing ). The valve angle on a small chevy is 23* and the Ford FE angle is 13*, so the ford does not need any help in this area. DF
Thanks, that was the info I was looking for. I really hadn't planned on milling the intake anyway.... why the heck do I need 10.7:1 compression in a 4x4 anyway?
I do have a source on 428CJ heads, actually the whole damn engine (out of a '68 Cougar) but the block is trashed and the crank is most likely garbage too. They guy won't let go of it for reasons unknown. It's been sitting for about 15 years and I think the sight of it makes him think of the glory days of old.
It is interesting how different environments will lead to different ways of doing the same thing. I have only heard of milling the intake face of the head to compenstate for head/deck milling. While i can see that it will be just as effective unless the manifold sits on the block. It all depends on what is most valuable. You would normally choose to mill the piece that is least expensive and for FE's that may not be the manifold.
Milling and FE manifold is possible more time consuming that the sides of the heads. I've always milled my intakes but I also had to fix other issues at the same time like warp after welding and othe alignment issues.
I think we (at the speed shop primaraly chev and holden) chose to mill manifolds so that the heads were as stock as possible so that the could be used on other blocks and resold etc.