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Registered
Join Date: Feb 2002
Location: Central NJ
Posts: 568
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3.2l Track Engine w/46IDAs running rich..
I have a track car with a 3.2l engine using 46IDAs that seems to be running rich. The original carb setup was done with my Supertrapps with no disks. Since the original setup, I have installed the disks back on the Supertraps. I believe the additional back pressure is causing the engine to go rich.
Engine is a twin plugged 3.2l, ported & polished, using Pauter rods, Ti retainers, 964 pump, Cosworth 11:1 pistons and an Elgin cam similar to a GE80. Engine comes into its own from 5500 up and could probably spin to 8K easily, but I never go over 7.2k. There is really no flat spots, but exhaust looks/smells rich. Car pulls nice but there is a lag (bog down?) at about 3k to 5K that could be caused by the cams or perhaps due to carb richness. Carbs are currently using 60 idle jets, 160 mains and 165 air correction. I'm trying to lean it a bit, should I go with 155 or 150 mains? Should I change the idle jets? I searched and I could not find any info on setting up large carbs on engines bigger that 3.0l. Thanks! Lou
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'76 911 "Moneypenny" daily driver '74 911 "JLo" IROC DE Car '03 CRV, '02 Jeep Grand Cherokee '03 Holiday Rambler Admiral SE, 30ft, 8.1l, 340HP, 455Ft# http://www.nicotra4.hpshare.net/BasketCaseMotorsports/ |
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04-14-2007, 05:05 PM
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Registered
Join Date: Feb 2002
Location: Central NJ
Posts: 568
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bump
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'76 911 "Moneypenny" daily driver '74 911 "JLo" IROC DE Car '03 CRV, '02 Jeep Grand Cherokee '03 Holiday Rambler Admiral SE, 30ft, 8.1l, 340HP, 455Ft# http://www.nicotra4.hpshare.net/BasketCaseMotorsports/ |
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04-16-2007, 04:14 AM
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Join Date: Dec 1999
Location: Novato, CA
Posts: 4,740
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Carbs? I thought they went out with the model A.
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04-16-2007, 02:01 PM
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RETIRED
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Take the discs off, pull the plugs. First find out if the discs did the deed. If it goes back to prior burn pattern then by all means go with a smaller jet.
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1983/3.6, backdate to long hood 2012 ML350 3.0 Turbo Diesel |
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04-16-2007, 03:43 PM
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Join Date: Jun 2004
Location: Rio Rancho, New Mexico
Posts: 1,325
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Lou,
You may not like this but.............. Get a hand full of idle jets and main jets, go to a dyno and find out on the dyno what works best. Always double check the jets for correct size. I have found the markings don't always match up. What size venturi's? I'm guessing 38mm would be best for your engine. Good luck,
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DOUG '76 911S 2.7, webers, solex cams, JE pistons, '74 exhaust, 23 & 28 torsion bars, 930 calipers & rotors, Hoosiers on 8's & 9's. '85 911 Carrera, stock, just painted, Orient Red |
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04-16-2007, 04:28 PM
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Join Date: Dec 2001
Posts: 4,313
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On my 3.4 twin plug race motor with 46mm Webers, 10.5/1, stock heads, DC80, Electromotive HPV-1, 1 3/4" headers into flowmaster 80. Same power band as yours.
mains: 170 air corrector: 180 emulsion tubes: f3 idle: 60 venturies: 38 pump jet: 50 I would get rid of the Super trapps. You end up adding a lot of disks and loosing top end power to try and quite it down. The Flowmaster has worked out well. 92 db full throttle at Infinion (Sears Point) I used an LM-1 to dial it in, then a chassis dyno to confirm. '75 Carrera (RS look)
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Harold '79 930/DP935 (sold) '68 VW 3.3 Turbo Crewcab |
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04-16-2007, 04:57 PM
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RETIRED
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When you ADD discs...they get louder.
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1983/3.6, backdate to long hood 2012 ML350 3.0 Turbo Diesel |
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04-16-2007, 05:00 PM
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Join Date: Dec 2001
Posts: 4,313
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Duh! Been a long time since I used them.
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Harold '79 930/DP935 (sold) '68 VW 3.3 Turbo Crewcab |
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04-16-2007, 05:13 PM
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Da cab
