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Author
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Topic: Hood Scoop causing carb headaches
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 09-19-2004 10:50 PM
   
I've been having trouble keeping a good carb tune on the Mustang and I've come to the conclusion that the problem is the SCOOP! Every time the temps change a few degrees the carb acts up. During the warm day the car runs perfect. In the evening when it gets cooler, it starts popping under full throttle, like it's running lean. I attached a thermometer inside of the breather tonight and took the car for a ride to the corner store. I drove it hard all the way home and shut it down quickly and checked the thermometer inside the cold damp breather and it said 36 degrees!! If the outside temp is 66, How can it be 36 deg. inside the breather?  It sure would be nice to have a computer controlled fuel and ignition system. ------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank, rods and girdle, TFS alum. heads, Stealth 8020 intake, Xtreme 268 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
11.86 @ 116 mph (7.62 @ 93 mph)daily driver!
DanH
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Fastymz
Moderator Posts: 18703
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 09-20-2004 01:56 AM
Dan, I really don't have that problem unless it's under 40 outside. Then I get alittle popping until my car warms up.------------------
SCOOP "Half this game is ninety percent mental."
- Yogi Berra
65 coupe,351w,C4,Big Boss 429 hood scoop,8" 3.40 TracLoc.
My Pics
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 09-20-2004 09:56 AM
I know just a cowl hood would be better but everyones got one of those. My hood is custom made by me, and the big scoop gets a lot of attention and cool points. 
How did the older factory carbureted cars with cold air induction deal with the temperature changes and keep the carb from running lean??------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank, rods and girdle, TFS alum. heads, Stealth 8020 intake, Xtreme 268 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
11.86 @ 116 mph (7.62 @ 93 mph)daily driver!
DanH
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mustangboy
Gearhead Posts: 774
From: Ont, Canada
Registered: Mar 2002
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posted 09-20-2004 01:17 PM
A lot of the older muscle cars had some sort of vacuum accuated flaps that opened to the outside air only when you were standing on the throttle.Other wise they were getting warm under hood air.Is there some way you can block off the scoop for driving in cool damp air?Maybe stick a normal style closed air cleaner on for those times.------------------
1968 mustang j-code sprint.13.69@101 306cu.in, stock ported heads,weiand exellerator,650 holley DP,hedman hedders,comp 292 Magnum cam,4-speed,8 inch 4.11 detroit locker http://mustangsandmore.50megs.com/MembersPics/mustangboy.html
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Fastymz
Moderator Posts: 18703
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 09-20-2004 05:22 PM
Dan, you could move your heater hose close to the carb on those damp cold days or nights. We don't get a lot of humidity around here. So that might be the difference,also I don't drive my car when it's colder then 40 degree's outside.A lot of those factory cars also used the heat riser tube from the exhaust manifold hooked to the air cleaner. ------------------
SCOOP "Half this game is ninety percent mental."
- Yogi Berra
65 coupe,351w,C4,Big Boss 429 hood scoop,8" 3.40 TracLoc.
My Pics
IP: Logged |
Fastymz
Moderator Posts: 18703
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 09-20-2004 05:36 PM
I've been thinking about making a curved deflection shield that would fit around the front half of my air filter. I would use it when it was cold out or to give more protection from the rain.------------------
SCOOP "Half this game is ninety percent mental."
- Yogi Berra
65 coupe,351w,C4,Big Boss 429 hood scoop,8" 3.40 TracLoc.
My Pics
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 09-21-2004 01:10 AM
Thanks for the ideas but since the whole reason for the big aero scoop was to draw in cold air, I guess I'll just have to get used to dealing with it. I went out and rejetted the carb this evening after getting tired of hearing the engine moaning from fuel starvation. I first tried bigger squirters but it only felt right after the car was up to speed, so I went from 75/84 up to 77/87 on the jets. Now she's feeling frisky again. One of these cold nights I'm gona take it to the track and see if the scoop is actually helping. I think I can fit a 14x3" drop down filter under the hood. As far as the rain goes Scoop... I drive my truck when there's any threat of snow or rain. I don't like to get the stang muddy unlees I have to! ------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank, rods and girdle, TFS alum. heads, Stealth 8020 intake, Xtreme 268 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
11.86 @ 116 mph (7.62 @ 93 mph)daily driver!
DanH
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