350 carb jetting issue
I have a 75 SBC 350, stock cam, heads, etc. The engine is in decent shape, recently I pulled off the stock cast manifold and replaced it with an Edlebrock Torker manifold along with a Holley 4160 series 600cfm carb, that I have just rebuilt. Now here's my problem, after putting the carburetor on the engine, it ran good at idle, once given throttle it choked out, I nailed the problem down to a blown power valve. So i removed the carb and rebuilt the entire thing, so now I have it all back together and on the truck. It starts up decent and idles nice, the only problem I have now is what appears to be an extremely righ mixture. With the float levels set correctly, I still have very little adjustment with the idle mixture screws. They will not even choke out the engine when seated completely lean, instead they bring up manifold vaccum, which leads me to believe they are leaning out the mixture more towards stoich. I could previously see it was running rich by way of exhaust fumes/smoke before i seated the mixture screws. The vaccum goes from about 18" with the mixture screws 2 turns out, to 20" when they are lightly seated, and the visual of the exhaust tells me it helped lean it out some, the stock jets in the carb now are a 66. My question is, how low should I go to begin getting a good baseline to tune from? Or could this issue possibly be something else? ... on another note, closing the manual choke, will kill the engine and opening it up even when cold will make it run perfect, which is also pointing me towards the jets being to large for this setup, which is why it needs the added air from the open choke.
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01-15-2005, 12:53 AM
