Intake Manifolds

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John Vardanian
Posts: 1906
Joined: Wed Sep 04, 2002 12:13 am
Location: San Francisco Area

Intake Manifolds

Post by John Vardanian »

Many months ago when I removed the carburetors and the manifolds I did not bother to mark their order and their rotation orientation because they all looked identical and also symmetrical. When I was putting things back together last week, I noticed someone had punched “1C”, “2C” and “3C” on the manifolds, so I thought what the heck, I’ll put “1C” in the front and so on. Then after I bolted the carbs on I noticed the fuel rail would not match up to the carbs, so I undid things and flipped the manifolds 180 degrees at random (while keeping the 1C, 2C, 3C order) until I got the fuel rail to mate with all the carbs. Today, I tried to fit on the air box, and boy, the holes are way off. What is going on here?

john
PF Coupe
BobA
Posts: 103
Joined: Tue Nov 12, 2013 7:36 pm

Re: Intake Manifolds

Post by BobA »

How about reverse assembly? Fit the air cleaner bottom to the carbs, then the fuel line to the carbs and then fit the manifolds to the carbs and the heads loosely without tightening anything to final and seeing how it fits together? Assuming you are using all the same parts, some combination will be correct. Was anything machined?
DWR46
Posts: 621
Joined: Tue Sep 22, 2009 8:23 pm

Re: Intake Manifolds

Post by DWR46 »

John: I have seen many manifolds numbered on various engines over the years. However, I am not sure who did the stamping. I do not know if it was done by the factory or at a later time. I would recommend that you carefully check each manifold for the fit at the intake port between the manifold and the heads. If the factory numbered the manifolds, they would have done it to identify the "port matching" they did by grinding the heads and manifolds to get perfect air flow. If you find that certain manifolds align better with certain cylinders, then you have your answer.
John Vardanian
Posts: 1906
Joined: Wed Sep 04, 2002 12:13 am
Location: San Francisco Area

Re: Intake Manifolds

Post by John Vardanian »

Thanks Dyke and all. I wanted to report that the problem was solved with a small compromise of a 1mm shim at one of the fuel rail ports. I properly marked the manifolds so I won't ask you this same question in a couple of years.

john
PF Coupe
BobA
Posts: 103
Joined: Tue Nov 12, 2013 7:36 pm

Re: Intake Manifolds

Post by BobA »

Thanks for the follow up, John. I wish everyone would do that so we can all learn from the solution to a problem.
John Vardanian
Posts: 1906
Joined: Wed Sep 04, 2002 12:13 am
Location: San Francisco Area

Re: Intake Manifolds

Post by John Vardanian »

Sure, Bob. I guess the moral of the story here is, at lest with may car, that even though the parts look identical and have identical part numbers cast into them, they fit differently.

john
PF Coupe
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