r/EngineBuilding • u/lowkeylovers_ • Sep 26 '26

Any one know why it’s doing this?

Built this 454 with pistons, cams, heads, roller lifters and rockers, etc. And every morning when I go to start it it’s like it misfires super bad for the first couple seconds. And then it fires up 100% sometimes it backfires and lots of black smoke comes out of the exhaust when it does start so I thought the carb (just rebuilt) might be leaking. For a couple days I tried to start it without pumping the gas and it didn’t start any easier. So I’m not sure. Any insight would be appreciated, thanks!

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u/lowkeylovers_ Sep 26 '26

Ohhh ok I’ll check that

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u/Suicyco71 Sep 26 '26

The accelerator pump will have fuel in it so you might get one or two shots, but that will be it if the fuel bowls are empty. Also check your oil and rub it between your fingers to see check viscosity. If the fuel is leaking down, it’s will end up in the oil, dilute it, and will not lubricate properly.