C2 Intake manifold alignment_Ch. 2

[Steve D.]

327 , aluminum manifold 3844461, heads 3890462

Based on replies to a recent post, I fashioned a pilot post and placed it in the distributor hole. Then I slid the manifold over the pilot and into position. Very slick, except that I still had the same problem. That is, if the manifold is positioned so that the bolts on one side can be threaded in with fingers, the other side is slightly off center causing the bolts to bind so that with diligent effort only about one thread can be started with fingers. The bolts can be tightened without crossthreading or galling, but it takes some patience and a lot of tapping to keep some of the bolts from binding too much.

I read a thread in the archives discussing manifold alignment, and one solution mentioned was to elongate the holes on one side of the manifold. My question is this: is the "tight bolt" situation I described normal, or should I be considering modifing the holes a bit to relieve some of the bind? (These are the same manifold and heads that were on the car before disassembly)

Steve

[Scott Marzahl]

Re: C2 Intake manifold alignment_Ch. 2

I didn't follow the earlier post, did you have the heads surfaced or the block decked? Depending on how much a head is surfaced, the intake needs to be machined to match.

[mike cobine]

Re: C2 Intake manifold alignment_Ch. 2

In building engines, I've often had them a bit too tight to thread by the fingers, but that isn't necessarily a bad thing. The only ones I've had problems with were ones with some head milling, such as an intake on a set of heads angle cut 0-100 with an index on the top of the deck, not the edge of the head.

That one we had to redrill the intake holes becaue of the change in angle on the bolts. But even then, it wasn't a lot.

Start by putting in a bolt int eh center on each side and then install the rest. Don't tighten any, not even finger tight, until all are in.

[Craig S.]

Re: C2 Intake manifold alignment_Ch. 2

I agree with Scott - sounds like a decking issue....Craig

[Scott Marzahl]

Re: C2 Intake manifold alignment_Ch. 2

I guess the other question is, what kind of intake gaskets are you using, thick enough for a good compressed seal, if so, maybe it is just the gasket thickness.

[Steve D.]

Re: C2 Intake manifold alignment_Ch. 2

No machine work was done on either the heads or the manifold after disassembly. Gasket set is Fel-Pro MS 9617.

[Joe C.]

Re: C2 Intake manifold alignment_Ch. 2

If the block was decked, that will cause the same condition. We don't admit here that the block was decked, right?

Joe

[Steve D.]

Re: C2 Intake manifold alignment_Ch. 2

Joe

The motor is not the original. A couple of years ago someone on this board identified the casting as a service replacement block. The numbers on the pad (which don't match anything) look undisturbed, so I don't think it has been decked.

Steve

[Mike McKown]

Re: C2 Intake manifold alignment_Ch. 2

If your bolts are rubbing the holes on the OB side of the manifold, it would lead me to believe someone has milled the port side and base of the manifold. Thicker than stock port gaskets and silicone on the ends should fix it. The thick gaskets will also bring your intake ports back into alignment.