Trouble with my 3794129 manifold

[Stephen G.]

I purchased an intake for my 63 L76 build up project on ebay. I just realized that someone must have modified it along the way. Normally on the rear deck just off center (below the level where it's stamped with 3794129) there is a "riser" that's about 2" in diameter and 1/2" high. I just realized it's not on my manifold. I can only guess that it was machined off. There is zero trace that it was ever there.

So now I wonder is this going to effect performance - ie did they do something with the flow inside and will it affect judging ?

[Franz E.]

Re: Trouble with my 3794129 manifold

The 3794129 340HP intake was unique for 1963 model year. There were two versions released for production. 1) Early production intake DID NOT have a power brake boss cast on the rear of the intake. 2) Second or later design incorporated a boss to accommodate a power brake vacuum hose. There were also two versions of the later design varying with the boss location. It is generally accepted that the boss was never drilled and taped during the 1963 model year. The brake vacuum was taken off of the rear of the carburetor. The first know use of the boss was for the 1964 model year and the part number was revised to 3844461. You may have an early 3694129 intake. By removing the retaining rivets from the heat shield you can determine the casting date. The intake casting dates on pilotline and early production 340 cars will range from May 1962 to about October of 62. The second design intakes began to appear with casting dates beginning in November of 62. These are only approximate dates.

[Stephen G.]

Re: Trouble with my 3794129 manifold

Thanks Franz. This now makes sense. I had never heard about the P/B boss. This is what I was attempting to describe. Since the intakes are not judged on date, it should be OK.

Steve

[Craig S.]

Re: Trouble with my 3794129 manifold

Steve - given the clarification Franz provided, even though there are no dates on aluminum manifolds on the top side, this obvious difference as Franz described could be an judging issue if you use the early manifold on a late car if the judges know the transition time frame Franz described. Food for thought...Craig