Off-Idle Hesitation

[rdorman]

Originally Posted by CWizard

Hey guys -The title pretty much says it. I can't read the numbers on the damper. Rechecked my timing while totally awake and the real numbers are 22 initial, 34 total. Exactly the same as when the engine was dynoed by the builder. Rdorguy, I tried the small tap on the primary accelerator pump and to my amazement the engine almost died! Recovered immediately, though. So I'm either too rich or right on the hairy edge. Since it idles fine and the idle mixture screws are about 1 1/2 turns out, I'm thinking the latter. But I may be too close to the edge since I tuned it with the air cleaner off.

I think timing is OK so I'm going to retune the carb (this time with the air cleaner on), and maybe try smaller primary pump nozzles. Will probably check the idle transfer slot unless a dramatic change occurs from retuning. It'll be a day or two, since I'm wrapping up another science project - I'm measuring the pressure loss caused by my remote oil filter setup.
Thanks to everyone for all the help.

Sounds like you are on the right track! Give your air bleeds a little squirt of cleaner. I do it everytime I have my aircleaner off. Check the transfer slots first and get them right. Then use the tap trick and set the idle mixture. You don't tap the pump hard, just enough to get a drop out. If the idle gets better, turn the idle mixture out, worse, in. About 1/8 turn each and try again. When you are close, an 1/8 out and tap will make it worse, 1/8 in and tap will make it better. The difference will be subtle. Four corner idle? Repeat on the secondaries. Have about 2/3 of the air fuel coming from the primaries. Repeat tapping both pumps and turn all four equally about 1/16th of a turn.

I don't recall, but you did check the accelerator pump to be sure that fuel comes out immediately didn't you?

Take a look at a plug. Soot around the top of the body (near the threads) is a good indicator of a rich idle (which leads to a lean transfer curcuit). Ideal is about 1 turn out.

Change the cam and squirter back to stock. Rarely, do they need tuned. If this doesn't do it, we will go from there!