Odd engine behavior after first shutdown of the day

[mrmustang]

Originally Posted by sea2jet

Vapor lock?

Given his location, that was my first thought, my 2nd is that he is on the ragged lower edge of the carb and even with custom tuning (needs a chassis dyno for it). it may be too much for the engine. Sure, runs great when cold, heats up, timing and subsequent vacuum to the engine changes when the choke heats up and kicks in, or out for that matter. I've had similar issues over the years, it all boils down to (no pun intended) to timing, jet sizes, vaccum......My full day, and unlimited carbs to swap out on a chassis dyno taught me an awful lot of what happens when the motor is in the chassis, and the parasitic pull of the rest of the drivetrain comes in to play. Apples and Grapefruit different between an engine dyno tune and a chassis dyno tune. Those that have done both know what I am getting out.

What is your initial timing, then what is your timing once the engine is warmed up? Jet sizes? Vacuum cold, hot? Manual or electric choke? Intake, a standard Vic jr, or a Super vic jr? Engine compression cold, engine compression hot? So many factors and items that can play it to what you are attempting to describe here.

Finally, have you checked that everything is torqued down, intake, exhaust manifolds, heads?


Bill S.