AFR curve
Posted: Tue Oct 03, 2023 5:17 pm
433 BBC drag only ho-hum Nova bracket car. 3k lbs. with me and has been 6.0's. My best set-up is an old C454 dual plane with a lean 3 circuit 9375 on gas. I don't get much tnt time so I'm asking for advice to correct the carb tune. My biggest issue is trying to stage for footbraking, under 2600 rpm. It's not clean down low, like it surges a couple hundred R's.
Floats are at 7/16, maybe a little high?
Fuel pressure is at 6 and I think it stays there for the entire run.
HP blocks with 4 holes and inconsistently drilled from Holley. Timing is 35 to 39, isn't locked but all in at 2300.
28/29
blocked
30-32
30-32
IAB-43
IJ-30
Inter AB-70
Inter Jet-39
MAB-30
MJ-94
TSR-73
MW exit-160
Banjo pin-160
Squirter-62 I know this seems extreme but I've been bit with a lean bog when air changed and I didn't catch it.
Bypass Air-140
1st gear AFR @
1200-22
1700-18
2100-17.7
2300-15.6
2600-10.7
5700-15.2
5900-14-13
6450-14.5
2nd gear
6450-13.89
3rd gear
6660-12.69
I'm thinking a smaller TSR might get it leaner and cleaner just off idle but will it stay clean at 2200 and up? In 1st, against the converter, it gets fat and then shoots lean during launch. Any advice is greatly appreciated.
Floats are at 7/16, maybe a little high?
Fuel pressure is at 6 and I think it stays there for the entire run.
HP blocks with 4 holes and inconsistently drilled from Holley. Timing is 35 to 39, isn't locked but all in at 2300.
28/29
blocked
30-32
30-32
IAB-43
IJ-30
Inter AB-70
Inter Jet-39
MAB-30
MJ-94
TSR-73
MW exit-160
Banjo pin-160
Squirter-62 I know this seems extreme but I've been bit with a lean bog when air changed and I didn't catch it.
Bypass Air-140
1st gear AFR @
1200-22
1700-18
2100-17.7
2300-15.6
2600-10.7
5700-15.2
5900-14-13
6450-14.5
2nd gear
6450-13.89
3rd gear
6660-12.69
I'm thinking a smaller TSR might get it leaner and cleaner just off idle but will it stay clean at 2200 and up? In 1st, against the converter, it gets fat and then shoots lean during launch. Any advice is greatly appreciated.