hotrod942

How much should ur dial in range from say 3pm @ 100 degrees till say 10pm @ 75 degrees...My car gas/carb/sbc for some reason will pick up a tenth in this situation.....Then u go to next round and the air/hum can be the same as before and the car will slow down about 2 hundredths.....they tell me to start with the jetting first..{plugs are a lil rich,but not that bad}also i'm gettin a lil black smoak out of the headers...... Anyone know where to start @ lookin for answers in this...Thanks

Tod74

Are you sure you are staging it EXACTLY the same every time? It will pick up as the air gets better but I wouldn't think it would slow back down in the same "better air"...unless the temp in the engine was quite a bit different from one round to the next. but I aint been doing this as long as most here have...so that's just my opinion.

fla1976

There are alot of variables to consider. Is the engine the same temp every run? Are the tires inflated the same every run? Are you refueling after every run so the car weighs the same? Are you monitoring the track temp as well as the air temp and humidity. Are you staging the same? The car will pick up with cooler air, but I know that my car slows badly with high humidity. The main thing is to be consistent in everything you can control.

hotrod942

Thanks for the info guys ,i staged the same every round,get very good consist. lights,put fuel in it every other round....What yall think about the black smoak coming out headers ?????? Thanks for all the help

hotrod942

Most of the 60' are right on but The car slows down mostly in between the 330' & 660',i pretty sure im in the groove...Thanks

hammertime

run gas on lean side for it to be consistent. a tenth is a long ways in one night, i'd be working on mine if it moved more then 3-4 with that change in temp.

promodjohn

It sounds like you are too fuel rich lean that puppy up and go faster and as the temp. and hum. decrease increase jet size.
You may also want to put a thermo couple in #3 cyclinder header tube 2" from the header flange and monitor EGT this is an inexspensive way to tune your fuel air ratio.

cepx111

Sounds like to me your carb is way on the rich side, you think it picks up now with that jetting in the heat then wait till it cools off this fall and it will pick up big numbers.
You'll get much more consistency with a carb on the lean side in bracket racing than with a fat carb.
I would go at least 2 jets sizes down on both ends of the carb for starters, read the plugs and go more if you can, but be careful not to go to far and make sure you dont get carried away with total timing, somewhere around 37 to 38 is where you'll want to be.
Goodluck, Charles