I have just got my car running right and now the carb will spit say from a dead stop in first or even 3rd. It isn't all the time but does happen. It isn't a backfire but that well I call it a spit. I have just re curved my distributor etc along with messing with jetting over the past few weeks. I'm suspecting That I need to bring the primary jet from 71 to 72 or so. I have noticed the headers are now running hotter so I think I jetted it down to much and now that the timing is on it wants more gas. I have 71's in front and 74's in the rear. I set the idle screws using a vacuum guage and the floats are about a quarter full. My exhaust does have a strong smell but I think that is normal for a hot rod. Any ideas.

have you tried a bigger shooter?

and the floats are about a quarter full The float bowls should be full to the bottom of the checking hole located on the side of the bowl. The fuel level within the bowl has an effect on the idle mixture being that the fuel within the idle feed wells raises and lowers with the height of the fuel within the bowl. At least that's how I understand it. If the carb is spitting the engine is just not accepting more fuel. What kind of spark advance curve did you end up with, intial, and mechanical?

My holley didn't spit until I changed my timing. The car has an initial of 18-20 degrees and a total of 36 with a full advance of 45(with vacuum). It idles great and seems to run good minus this spitting. Do you think it could be the jetting is off a bit. Now as for the float levels are you saying they should be full of gas instead of a quarter full or so? Now it isn't a backfire it just comes back but then responds fine. I can't tell if it wants more fuel or what. When I give it hell the car seems to run fine. I guess the timing could be a bit much but 18 is what it took to get a 900 rpm crisp idle.

With the engine running and warm the float level should be at the bottom of the sight plug.

that is exactly where I have it set. My question is if the carb spits like that at random which is the most likely cause. I just re did the timing and suspect maybe it is a tad lean now. The car seems to run great from the settings I have put in. It starts pretty easy etc. Before I set the timing correctly the carb was not exhibiting this issue. I have 71's in the front and 74's in the back. 3.5 pwr valve with anti blow protection.

Don't mess with the timing,the engine is most likely just more effecient and running lean.Jet the primary up a couple of sizes,drive it and see how the plugs look and how the engine responds to the changes.

Had an off idle stumble-bog on my 750, just went from a .028 squirter in front to a .033 and it's gone. My buddy had the same problem on his 455 GS he tried EVERYTHING and it worked on his also, actually that's where I got the idea!!! Mike

Maybe it is the squiter but I have had issues in the past with it running rich but I think that was because of my timing being off and the wrong curve kit in my distributor which has been fixed. I have this 750 on a 406sb.