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Author Topic:   Another 4412 Problem
RangeRover
Dirt Freak

Total posts: 279
posted February 23, 2005 05:23 AM  
I noticed this troubling problem a while back and I haven't been able to fix it. This is the only 4412 2bbl that I've ever bought new out of the box, too. While idling the engine with the air cleaner off I look in the carb and pick up the throttle slowly. The right side booster begins to dribble fuel way before the left one starts. I've torn it down several times and thoroughly cleaned every orifice with carb cleaner and an air nozzle. My buddy said that the engine might have a stronger vacuum or signal on the cylinders that correspond to the right side of the carb through the dual plane manifold. I'm thinking that the boosters are the main circuit so they operate on air velocity (rpm) and not vacuum, but I tried it on a completely different engine and it does the same thing. Some spark plugs are tan and others are black as you might expect. I'm not sure if this problem affects me at racing speeds, but I don't think it's right.

Any suggestions?

KPLugnut
Dirt Forum Champ
Total posts: 1019
posted February 23, 2005 06:41 AM  
The boosters aren't aligned properly, and one idle transfer slot has been milled longer than the other causing the main/transfer circuit to activate prematurely in that side. A common problem with mass-produced carbs, unfortunately.
The fix would be to have the carb professionally blueprinted.

KP

racin78p
Dirt Freak

Total posts: 333
posted February 23, 2005 01:44 PM  
Nothin' like advertising KP. Heh, heh.

Actually mine does the same thing and when you guys get a little caught up, I'll call and get it sent to you so you can do your "majic". Also, I noticed that when setting the idle mix screws at the end of last year, the right side didn't vary much. Left was fine. I figured on going through the carb this winter and give it a good cleaning (until deciding to send it to you guys). Other than dirt, what might cause the right idle to not adjust like it should?

Curious.

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racin78p
if it ain't fun, then don't run

KPLugnut
Dirt Forum Champ
Total posts: 1019
posted February 23, 2005 07:56 PM  
The same thing that causes the premature booster activation the above carb has, really. Mismatched transfer slots, plugged idle circuit, or a combination of that and crooked boosters.

Thanks for the kind words everyone. We are trying to play by the rules these days on the forums, too. As you'll notice, due to budget limitations, our banners are not all over the forums anymore, so we can't be jumping in all over "advertising" our services. This is NOT to say I don't support these great forums as much as before, and will most definitely be as available as I can to all racers.
Just gotta find me, that's all...I'm all over. :-)

KP

racin78p
Dirt Freak

Total posts: 333
posted February 24, 2005 01:15 AM  
Thanks KP. Kind of what I thought. Just don't have time right now to open it up. As a note, I thought that I had seen your banner here, and the other day I was looking for it and not there. But I have your number so I didn't freak. Didn't really mean to say you were really advertising either. Just joking. But I will say you guys know what you're doing with carbs and anyone that needs help, give them a call!

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racin78p
if it ain't fun, then don't run

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