Blowback through carb
Having difficulty tuning my rebuilt 327. Engine is knocked up with race performance internals and is the first time I've ever tried tuning a motor this hot. Whenever I try to start the engine, mostly when it's already warm, I have to crank it over and over and play around with pumping the gas pedal. Sometimes I have to pump more than other times and sometimes I don't have to pump at all and it will fire up. But most the time when it tries to start, burnt gas fumes and un-burned gas come jumping back out the top of the carb. Lots of smoke and really embarrassing! Whenever i use a shot of starter fluid then crank it over, it fires right up. I've adjusted timing and even main jets on carb. which is a QFT 680. Could I possibly have the wrong aluminum head spark plugs or maybe not enough spark? I have a 12:1 compression, mallory distributor w petronix II ignitor and a 40,000 V coil.