New Holley 4 bbl
Just purchased a 87 Minnie that the previous owner had a New Holley 4 bbl recently put on, went to get the rig smogged and the tech said it was running too rich and it didn't pass. When he did the H...
Forum Discussion
Mbrown wrote:
Have been researching this topic of glowing exhaust on line and some say too rich, others too lean, also possible causes are; catalytic converter clogged, o2 sensor, throttle position sensor, cracked manifold or timing. The timing was off 3 deg but dont think that was problem...
Where to go next ???
Uneven mixture side to side would come from the carb only if one side of the carb feeds one side of the intake manifold. I don't know the distribution for your intake.
Other sources of overheating on one side exhaust can be too much air going in (intake manifold fitting or gasket leaks), or as you've mentioned, air leakage into exhaust manifold or blockage of exhaust on that one side. Anything that is the same for both sides, e.g. ahead of the carb or after the exhaust is joined, would not be the first places I would look.
I would not expect to find O2 or throttle position sensors on a truck without fuel injection, as those are among the inputs to the ECM. O2 sensor is for operating injection in feedback mode rather than off the mixture and timing maps.
