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  #1  
Old 03-21-2003, 10:44 AM
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Confused Carb Problems

Have a 70 383 that had a two barrel carb. and was changed to a 4 barrel.It is real cold blooded,wants to die at idle,and miss when I take off.Its a Holly 1850 and has the adapter plate under it,the intake is factory I think #2205968,A 270/280 cam is in it ,and it is a a/c car.Any idea's of what may be wrong ,and is this the right carb for this set up?Also who has the best prices on Ccarbs and kits.Thanks
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Old 03-21-2003, 12:52 PM
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I moved this to the Performance Forum because I felt you may get a more specific answer here. Just for starters, I'd check accelerator pump operation, and the plate under the carb and the carb for vacuum leaks by carefully spraying around it with carb cleaner. If your idle speed changes-increases, you are definetly pulling vacuum in, unless you spray it completely into the top,lol!
Hopefully someone else here is running your cam in a similar engine and may have some jetting and tuning info as well.
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Old 03-22-2003, 11:29 AM
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Is it good when it warms up?
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Old 03-28-2003, 07:24 PM
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Still wants to die and back fire on fast take offs. Thanks
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Old 03-28-2003, 07:44 PM
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First off you are way better off putting a 4bbl manifold on there instead of using that adaptor. It could be a vacum leak. Try and spray sole carb cleaner around the mating surfaces between the carn and the intake. If the car increses RPM then you have a vacum leak.

I have a stock HP 383 4bbl manifold with a 1971 casting # that is already sandblasted and ready for paint if your interested. I am willing to let it go for real cheap.
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Old 03-28-2003, 07:44 PM
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My first and only thought is that it is running lean. Every time I've had that problem I've richened it up one or two jet sizes and it worked fine. And the plugs look better. But then it is a Holly. I'm not familiar with that number.
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Old 03-28-2003, 07:47 PM
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That is a 2 bbl intake???? Get rid of it and get a 4 bbl one. I have had great luck with an Edlebrock Performer. That 383 4bbl one would work just fine.
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Old 03-28-2003, 08:27 PM
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sounds like an acc pump. how old is the carb? maybe you should start with a rebuild first. is it a 2bbl intake with an adapter? if so get that off there like everyone said before me.
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Old 03-28-2003, 08:30 PM
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cuda66273 might have the rebuild kits your lookin for
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Old 03-28-2003, 11:33 PM
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Thanks for all your help,I'm not much of a carburetor person.The carburetor is pretty old,list#1850-2 which my book shows to be a #4160- 600 cfm.As far as I know it is a factory 4 barrel intake,the spacer plate I'm talking about is theone that adapts from square bore to spread bore.Think I may just replace it,what are your thoughts on a Holley Street Avenger 670 cfm.Or is there a different one out there that would work better.Thanks again
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Old 03-28-2003, 11:57 PM
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Put a decent aluminum 4-barrel intake on that engine and then give it a 750 CFM carb. Even with the 2-barrel cam, it can still use what a 750 has to give.

I did that swap on a '70 Challenger with a 383-2, back in 1986. I used an EB Torker intake with a Holley 750 Vac Sec. That engine loved the 750 CFM.

Today, I would spend the couple extra bucks and get a Demon from FBO systems (cuda66273).
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Old 03-28-2003, 11:57 PM
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How old is the carb? I know that carb well. Its a sigle inlet side hung float Holley with Vacum seconds. There a simple carb. That carb will work well on a 383 or 360 for that matter. Make sure the float level is set up correctly. While your in there take a air hose nossle and blow out the metering block and main body good. (all the little holes. Set the idle mixture screws 1 1/2 turns out from full seat in. Dont strong arm them when turning them in. Blow the air bleds out too. If looking down the carb below the butter fly you will see 4 brass fittings with small pin holes. There is 4 in the back also. Make sure that the accelerator pump is working. Easy, just turn the car off, look down the carb below the butter fly, hit the throttle, you should see the squirts of gas any time you touch the throttle. Make sure you have planty of intial timing also. At least 10-12 deg initial.
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Old 03-29-2003, 07:25 PM
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Wondered how hard of a carb this is to rebuild,it would be my first.And is it a hard one to keep ajusted and tuned right.Thanks again
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Old 03-30-2003, 09:54 AM
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You can spend $40 on a rebuild kit.
This will replace the gaskets and a few moving parts. You'll spend all day on it.

You don't have the correct chemicals to clean it properly or the ability to tear it down and re-bush the throttle shafts which are probably worn out.

It's probably totally worn out and it won't matter how much time and money you spend it'll never work properly, there comes a time when you just need to junk that old stuff, save money, time and frustration and buy a new carb.

You engine is screaming for a 650 Speed Demon, electric choke and vacuum secondary... put a decent manifold on it....it'll be like a new car.

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Old 03-30-2003, 10:19 AM
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Thanks for the advice,probably be the best thing to do.Good luck at the track,and keep it straight.
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