Carb. Trouble

My car has started dieseling when I shut it off.
Isn't that a Carb. problem?

There are factors which will cause dieseling....hot running engine, carb running too lean.(throttle blades are open too much.)..fuel octane too low....carbon buildup....late timing... vacuum leak.idle speed being set just a little high...

Pops is on it. You can make sure the throttle blades are in the correct position by backing off the idle speed screw until the blades seat in the bore then open them 1 - 1.5 turns. If your idle is too low after that, advance the timing (within reason) until you get the correct idle speed. You should end up with 10-15 deg BTDC on a mild perf engine. Of course you need to make sure there are no vacuum leaks because too much air admitted into an engine on shut down can cause dieseling.

If you suspect carbon build up get a 16 oz soda bottle and make a 50/50 mix of water and brake fluid and trickle it down the carb while at high idle (approx 1500 RPM). Note: You will make a cloud of white smoke like you have never seen.

Meep-Meep said:

You should end up with 10-15 deg BTDC on a mild perf engine.

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And depending on the cam, some guys are running more like 15-20 initial. My little 318 with a really mild cam likes 17* just fine. Runs regular gas. I suspect modern alcohol fuel is partly the cause. Mine idles in neutral and about 900, and never a hint of diesel on a hot day. ( I run about 36 total mechanical with quick springs)