Thread: Dieseling New Crate Motor

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Just installed a new 454 crate motor with an Edelbrock performer series carb. After the motor has reached operating temperature and is turned off it diesels. This is a low compression motor that is supposed to run on regular unleaded. I was told to use premium gas and the dieseling would stop. It didn't.

Can anyone give me any ideas to try next. I suspect something to do with the carburetor but I am not an expert and have never experienced this before.

Originally posted by MacTexas
Just installed a new 454 crate motor with an Edelbrock performer series carb. After the motor has reached operating temperature and is turned off it diesels. This is a low compression motor that is supposed to run on regular unleaded. I was told to use premium gas and the dieseling would stop. It didn't.

Can anyone give me any ideas to try next. I suspect something to do with the carburetor but I am not an expert and have never experienced this before.

what do you have the base timing at and what rpm's do you have the motor idling at?

base timing is 12 degrees and idle is 1000

Originally posted by MacTexas
base timing is 12 degrees and idle is 1000

it would help to get the rpm's down. make sure you dont have a vac. leak. do you have vac. at the vac. adv. at idle?

First thing I would do is retarding the spark.

thank you for the quick reply. I will lower the idle and check for vacuum

Fatten up the fuel mixture. Lean mixture is contributing to elevated combustion temps resulting in hot spots in the chamber from a sharp edge/gasket overhanging the bore or even a burr on the spark plug electrode. Use a 180 thermostat and monitor the water temp just before the thermostat with a known-good gauge.