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Paul · 08-23-2007

The FI on the 75 Manta is not temperamental at all. In the stock, unmolested form, its very stable and nice to drive.

There are 2 problems.... (1)isn't not adjustable and (2) the flap door style air flow sensor doesn't like cams with a lot of overlap. The excessive overlap will make the flap bounce and drive the computer nuts. However, I ran an Isky OR-66 cam for many years w/o any issues... coupled with flat top pistons. The FI can't handle the really good cams with 106 or 108 centerline... The lack of adjustability means the FI system soon runs out of abiltity to increase fuel in the upper RPMs.... usually starts to go lean above 4500.

The engine I built for my 75 Manta, I kept these issues in mind when selecting components like the cam. You can build a fairly strong engine, say 110-115HP, and still use the stock FI, but that's about the limit

08-23-2007	#2 (permalink)
Paul Member 1000 Post Club Join Date: Mar 2002 Location: Ft Smith, Arkansas Posts: 1,481	The FI on the 75 Manta is not temperamental at all. In the stock, unmolested form, its very stable and nice to drive. There are 2 problems.... (1)isn't not adjustable and (2) the flap door style air flow sensor doesn't like cams with a lot of overlap. The excessive overlap will make the flap bounce and drive the computer nuts. However, I ran an Isky OR-66 cam for many years w/o any issues... coupled with flat top pistons. The FI can't handle the really good cams with 106 or 108 centerline... The lack of adjustability means the FI system soon runs out of abiltity to increase fuel in the upper RPMs.... usually starts to go lean above 4500. The engine I built for my 75 Manta, I kept these issues in mind when selecting components like the cam. You can build a fairly strong engine, say 110-115HP, and still use the stock FI, but that's about the limit __________________ Paul