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Old 06-12-2019, 05:48 PM   #1
hallass66
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Default tuning 2 holley 950 blower carbs

Have this posted on another site.Looking to get it better sooner.540 BBC all aluminum motor 871 bds blower with 2 holley 950s.Car was pig rich when i got the car.Removed both carbs and drilled and tapped everything to swap air bleeds air jets.Right now current set up is
IFR 29 came with 41
IAB 68 came with 72
HSAB 35 came with 32
Transition slot tapped to 81
idle mixture screws 1/2 turn out
main jets 75 sec 84
PV 2.5
no transfer slot on either carb exposed at idle
Car runs 13 AFR at idle and with slight tip in 2k rpm jumps to 15 AFR then 2500 to 3000 AFR drops to 12 AFR and full throttle drops to 10 AFR.Street car only running pump gas timing locked at 30 5% under driven about 4lbs of boost.Just trying to get good street manners without being so rich.Plugs look alot better now but still needs work.Any help would be appreciated.
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Old 06-13-2019, 06:34 PM   #2
738drvr
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Default Re: tuning 2 holley 950 blower carbs

Shoot jmarkaudio a pm. He’ll get you sorted.
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Old 06-14-2019, 03:16 PM   #3
jstahemi119
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Default Re: tuning 2 holley 950 blower carbs

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Originally Posted by 738drvr View Post
Shoot jmarkaudio a pm. He’ll get you sorted.
LMOL,,,,,that where he posted before here
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Old 06-24-2019, 04:46 PM   #4
wingnutks
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Default Re: tuning 2 holley 950 blower carbs

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Originally Posted by hallass66 View Post
Have this posted on another site.Looking to get it better sooner.540 BBC all aluminum motor 871 bds blower with 2 holley 950s.Car was pig rich when i got the car.Removed both carbs and drilled and tapped everything to swap air bleeds air jets.Right now current set up is
IFR 29 came with 41
IAB 68 came with 72
HSAB 35 came with 32
Transition slot tapped to 81
idle mixture screws 1/2 turn out
main jets 75 sec 84
PV 2.5
no transfer slot on either carb exposed at idle
Car runs 13 AFR at idle and with slight tip in 2k rpm jumps to 15 AFR then 2500 to 3000 AFR drops to 12 AFR and full throttle drops to 10 AFR.Street car only running pump gas timing locked at 30 5% under driven about 4lbs of boost.Just trying to get good street manners without being so rich.Plugs look alot better now but still needs work.Any help would be appreciated.
Increase IFRs and possibly decrease LSAB. Re-adjust mixture screws for best idle.
Reducing jetting to get WOT up from 10AFR. Depending on what your target cruise AFR is you may have to take jet of out primary, or secondary, or both.
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Old 06-27-2019, 07:58 AM   #5
drc767
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Default Re: tuning 2 holley 950 blower carbs

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Originally Posted by 738drvr View Post
Shoot jmarkaudio a pm. He’ll get you sorted.
Or better yet, have him build you a set of blower carbs from scratch. Mark has done 4 sets of blower carbs for me in both pump gas and E85 configerations, and every set has been spot on right out of the box except for the standard idle mixture fine tune and idle screw adjustment. The set I have on my 557" all aluminum, 14-71 setup are billet E85 carbs that Mark did for me.......perfect in every way!

Last edited by drc767; 06-27-2019 at 08:02 AM.
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Old 06-30-2019, 01:11 AM   #6
bad 68 chevelle
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Default Re: tuning 2 holley 950 blower carbs

Mine was running pig rich so I sent them to Mark, he converted them to E-85, I put them on yesterday and haven't touched a thing, they were dead on. I drove to a show today in 90 degree heat and the blower was ice cold. Best change I made so far.
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