Well Folks,
I just finished neutering my 5.0 with GT40"P" heads from a Ford B303 cam to a stock Explorer cam. I was told that I would hate the cam and that it would lose all performance. NOT TRUE! While certainly not as stout as the B303, it still performs quite well up to/thru +4,500 RPM and fuel mileage should be greatly improved, etc.
Now for my confusion:
A) Throughout life with the B303, I played and played with the idle air bleeds on the QuickFuel HR-580 vacuum secondaries carburetor to try and tame the overly stinky rich exhaust at idle, all with little success. Current air bleeds are considerably larger than stock at .081 in the primaries and similar (can't read the numbers) in the secondaries. The car ran and drove quite well and was pretty quick and the idle mixture screws were at about 5/8-3/4 out. Vacuum was between 15 & 16.
B) Now with the new cam, with vacuum in the 20-21 range, I had assumed that I would need to (at first, before changing any air bleeds) turn the idle mixture screws out a bit farther to richen up the mixture a bit to compensate for the added vacuum and air. The surprise and confusion comes from needing to completely close the primary screws and slightly open the secondary screws to reach smooth running maximum vacuum. I also suspect that it would be even better if the primaries could be "closed" even more!
What Thinks You Guys?
Gene
I just finished neutering my 5.0 with GT40"P" heads from a Ford B303 cam to a stock Explorer cam. I was told that I would hate the cam and that it would lose all performance. NOT TRUE! While certainly not as stout as the B303, it still performs quite well up to/thru +4,500 RPM and fuel mileage should be greatly improved, etc.
Now for my confusion:
A) Throughout life with the B303, I played and played with the idle air bleeds on the QuickFuel HR-580 vacuum secondaries carburetor to try and tame the overly stinky rich exhaust at idle, all with little success. Current air bleeds are considerably larger than stock at .081 in the primaries and similar (can't read the numbers) in the secondaries. The car ran and drove quite well and was pretty quick and the idle mixture screws were at about 5/8-3/4 out. Vacuum was between 15 & 16.
B) Now with the new cam, with vacuum in the 20-21 range, I had assumed that I would need to (at first, before changing any air bleeds) turn the idle mixture screws out a bit farther to richen up the mixture a bit to compensate for the added vacuum and air. The surprise and confusion comes from needing to completely close the primary screws and slightly open the secondary screws to reach smooth running maximum vacuum. I also suspect that it would be even better if the primaries could be "closed" even more!
What Thinks You Guys?
Gene