carb tuning questions.
10-18-2015, 01:59 PM
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carb tuning questions. some more carb tuning question for you all.
when im cruising at about 2500rpms and give it enough throttle to about 3500rpms it goes lean (as high as 16.5AFR) for a second or two then goes back down. so i went and put primary accel cam in #3 positions(pink cam). also went from 40 P/S squirters to 45 P/S squirters. it helped some,now it only gets to 15.5AFR. those AFR numbers are rough numbers, it bounces around a little.
at what point do i stop with squirter size and worry about trying different accel cams? i do not have any throttle stumble so idk if this is even something i should worry about. at cruise im at low 13 AFR. if i change the primary accel cam position do i need to do same to secondary?
WOT im at mid 13s and sometimes i see 14AFR. i changed the HSB from 36 to 32. i think i ll wait till a track day to tune WOT by mph.
as always thanks for any input on my beginner questions
when im cruising at about 2500rpms and give it enough throttle to about 3500rpms it goes lean (as high as 16.5AFR) for a second or two then goes back down. so i went and put primary accel cam in #3 positions(pink cam). also went from 40 P/S squirters to 45 P/S squirters. it helped some,now it only gets to 15.5AFR. those AFR numbers are rough numbers, it bounces around a little.
at what point do i stop with squirter size and worry about trying different accel cams? i do not have any throttle stumble so idk if this is even something i should worry about. at cruise im at low 13 AFR. if i change the primary accel cam position do i need to do same to secondary?
WOT im at mid 13s and sometimes i see 14AFR. i changed the HSB from 36 to 32. i think i ll wait till a track day to tune WOT by mph.
as always thanks for any input on my beginner questions
10-18-2015, 05:38 PM
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i also have another issue. rich at idle. my carb has 6.5 powervalve. in neutral vacuum is 10-11 in gear its about 7. could this be giving me the rich idle problems? i know i need to reduce the size of IFRs. because i have to almost screw mixture screws all the way in. theres no adjustment.
10-19-2015, 05:28 PM
#3
Did changing the HSB affect the lean bit between 2500 and 3500?
At that RPM you are going from the intermediate to the main circuits. Depending on what vacuum is doing when it goes lean you might need to adjust the power valve. Making the idle air bleeds a step smaller might help as well.
As far as accel cams, by all means experiment with them. They have different shapes to put more or less squirt at different points in the throttle. There is also two different mounting holes on the cams. Allows you to advance the cam to bring it in sooner or later with throttle position.
At that RPM you are going from the intermediate to the main circuits. Depending on what vacuum is doing when it goes lean you might need to adjust the power valve. Making the idle air bleeds a step smaller might help as well.
As far as accel cams, by all means experiment with them. They have different shapes to put more or less squirt at different points in the throttle. There is also two different mounting holes on the cams. Allows you to advance the cam to bring it in sooner or later with throttle position.
10-19-2015, 07:44 PM
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last night i did a vacuum check. with it running rich in gear it was at 7. the carb has a 6.5 PV in it now. today i got a 3.5PV to swap in and i got the accel cam pack.the HSB did lean a little bit but i think i ll wait to tune that after idle and accel pump is figured out.
