I have a 1050 apd carb that is just very dirty and rich in the idle circuit it had a .046 air bleed mixture screws out 1.5 turns. I installed some .060 bleeds all I had close in size it has made it better mixture screws at 1 turn now. is it possible that it just has to big of a IDLE JET. it has been on 3 different motors for a 489-632 all with similar results.

Suggestions,
* if you have the build sheet, put all jetting back as it came from the builder. As a general rule, no jetting change should be needed beyond a step or two either lean or rich. The idle bleed change you made is very excessive and out of normal range.
* take it apart to clean and replace floats, needles, and seats, gaskets.

This^^^

no jetting has been changed at all except the air bleed

quote:

Originally posted by Larry Woodfin:
Suggestions,
* if you have the build sheet, put all jetting back as it came from the builder. As a general rule, no jetting change should be needed beyond a step or two either lean or rich. The idle bleed change you made is very excessive and out of normal range.
* take it apart to clean and replace floats, needles, and seats, gaskets.

the carb has maybe 30 min of run time on it from apd rebuilding it

there is an idle feed jet on the front of the body that can cause this,but be sure butterfly on both ends is not open too far pulling other fuel from intermediate.floats too high ect.if you start closeing the corner screws much less than 1 turn you will loose too much idle fuel volume

Many problems come from dirty air bleeds they are small and clog easy. When the air bleeds are working right you will notice RPM change as you open or close the idle mixture. If not then you may have some clogged and or as Rusty says float level too high dripping fuel. Blow them out with carb cleaner and listen to make sure they are open and flowing. Also float level must be good. Make sure boosters are not dripping at idle. Or people modifying the carb.
Bad throttle cable design can ruin throttle shafts quickly. Then they will be sticky and leak causing problems. There are some expensive return cable set ups that are pure junk.

quote:

Originally posted by camaro77:
I have a 1050 apd carb that is just very dirty and rich in the idle circuit it had a .046 air bleed mixture screws out 1.5 turns. I installed some .060 bleeds all I had close in size it has made it better mixture screws at 1 turn now. is it possible that it just has to big of a IDLE JET. it has been on 3 different motors for a 489-632 all with similar results.

What engine temp are you coming to these conclusions?

Does it warm-up in a reasonable amount of time with the lean-out open? If it's dirty & rich, it won't

The idle mixture screws should be set according to no stumble when it is decked on the trans-brake. I can't imagine it not stumbling with one turn outon the mixture screws.

Anytime I turn the mixture screws in or out, or change idle bleeds, the A # 1 test to run it through, is decking on the TB

When you start it, just open the lean-out until the temp gauge see's 170-175 degree's, then jack around with its tune. I'm 99% certain these APG carbs like to be 180 degree's on the starting line.

mike PM sent

Seeing how you won the race on Saturday I would probably leave it alone. That make 2 wins in like 3 weeks. Haha, Good job Jeff

thanks ken

My buddy was having some problems with his APD carb last month. I went through it and pulled the emulsion jets out and there was trash behind them clogging the second from bottom jet completely.

You can change the air bleeds all you want, if the emulsion jets are clogged, it will not respond correctly to the changes.