Gday I just fitted a 425 impco mixer to my straight gas 351 clevo XB. When i go to start it, the car will fire for maybe half a second and then stop. It wont stay running. It was fine before this when i had the 300A on it so what have I done wrong or can anyone give me a tip on getting it to run.

p.s. (might sound sily but...) will it fire without the air filter on or do i need to have it on?

This gas thing is all new to me!!

Just had a closer look at the top diagphram. I can see a tiny pinhole. So I guess this is the problem. I rang Impco but they wont sell me a new diagphram unless I have a gas ticket !!! Bugger

So would anyone have a good top diaphram to fit my 425??