Quote: I thought that when a restriction in the exhaust system is removed, the carburetor sometimes needs to be jetted richer. I'm going to lean out the primaries again to see if the numbers move. I'm just surprised that a less restrictive exhaust made the car run richer. I didn't change anything else....... The jet change resulted in less power and one incident of of detonation despite the gauge reading richer than the target.
Just some thoughts/questions. Did you check backpressure and verify a reduction? A 70 mph cruise should not have a significant change there, unless you had a really bad exhaust before- I've worked on plenty of cars that had bad Cats that would drive fine until you stood on it, then would fall on their face. and far as the the jet change don't focus on a "target number", give the engine what it wants. You don't have efi, so there are going to be cylinders that run leaner than others, and you are not monitoring each cylinder. I'd suggest you swap back the #83s and check again. If engine is happy, leave them. If not there may be a fuel problem- delivery, poor quality, sucking air, or carb. If the reading are inconsistent there could be a problem with the gauge. HTH, Steve
