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post #1 of (permalink) Old 12-15-2000, 09:31 PM
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2 Problems on rebuilding my Carb

I got the carb off the truck, and began taking it apart following all the instrustions the kit came with. I tried taking the choke plate off, but the screw heads stripped out. What should I do? Maybe just drill a little tiny hole down the middle of it and use a screw extractor? Also, what the heck do I use to remove the idle speed things? I think they are idle speed. There are 4 of them, and each one shoots into one of the 4 bbls on the carb. And one other thing, the kit tells me to (on the idle speed things) to count how many turns it takes to lightly seat the screws, record this number, and use it to put them back in. Do I really have to do this? Or is there a certain number of turns I should put them in to follow the factory specs? Or, (sorry about this) do I even need to take them out? Should I just leave them in and clean the unit with them installed. Thanks

Sean Heberly
'85 351 5.8L XLT Bronco
'86 Pontiac Fiero GT 4.9L NorthStar
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post #2 of (permalink) Old 12-15-2000, 11:28 PM
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Re: 2 Problems on rebuilding my Carb

1. You're not supposed to remove those screws. If you look at the back side, you'll see that they're split so they won't unscrew.

2. If you're talking about screws with big knurled heads and springs, they're idle mixture adjusting screws. Yes, you should count the turns to bottom them - it's a good benchmark to begin recalibrating them when you try to tune the carb. Yes, you definitely need to remove them and THOROUGHLY clean the journals and ports associated with them. They are VERY important.

Steve
83 Custom w/95 4.9L EFI, 78 NP435, 83 NP208, 83 D44IFS 3.07, 87 Ford 8.8ABS 3.08, Michelin LTX AT 31x10.50R15
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post #3 of (permalink) Old 12-16-2000, 08:58 AM
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Re: 2 Problems on rebuilding my Carb

Figures. I need to take the butterfly off to get to the little jets under it. This carb has already been rebuilt twice before, and those screws dont really look like they wouldnt come out, but what do I know. And, yes, Idle Mixture screws, thats what I am thinking of. What type of tool do I use to get them out? I cant seem to find anything that works. And I am good at stripping things out so I dont want to use somthing I'm not supposed to. I did, however, figure out what was wrong with the carb. Only 2 of the 4 bbls were opening. The back 2 were gummed up and wounldnt move for anything. Should purr like a kitten now.

Sean Heberly
'85 Bronco 5.8L 4-V XLT: 266K still strong. Winter Truck now.
'86 Pontiac Fiero GT: 4.9L Caddy NorthStar Engine, 11.6 QM @ 107.1 MPH, Poly Susp, KONI's all around, 2 1/2" drop.
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post #4 of (permalink) Old 12-16-2000, 12:16 PM
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Re: 2 Problems on rebuilding my Carb

The only "jets" under the butterflies are the accelerator pump ports that squirt fuel into the throats each time the throttle is opened. They should not be removeable, and as long as the fuel comes out in a spray, they're fine. Just use the tube on a can of carb cleaner to blast backward thru them. (You HAVE pulled the top off the carb, right?)

The idle mixture screws should have a plain slotted heads; if you can see the knurled parts of the heads, you should see that. They are low on the outside of the carb. Some of them have anti-tampering caps that completely enshroud the heads and springs: they consist of 2 hardened steel cups that interlock; one installed before the spring and screw, one after to cover them. They cannot be separated - you have to cut them apart with a Dremel, or break them (but you'll probably damage the carb that way).

Steve
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post #5 of (permalink) Old 12-16-2000, 05:13 PM
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Re: 2 Problems on rebuilding my Carb

Okay, Just got done and put it back on the truck. Runs great too. Yes, those were the "jets" I was talking about under the butterfly. I didnt remove the jets, just the screw and thing under it, replaced the gaskets. I had to use allen head wrenchs on the idle mixture jets, but they came out with no problem. Now, how do I set my idle up? I just want (in a sense) to have the gas pedel down a little more, and the truck idleing a tad higher. Thanks, you guys have been a great help!

Sean Heberly
'85 Bronco 5.8L 4-V XLT: 266K still strong. Winter Truck now.
'86 Pontiac Fiero GT: 4.9L Caddy NorthStar Engine, 11.6 QM @ 107.1 MPH, Poly Susp, KONI's all around, 2 1/2" drop.
post #6 of (permalink) Old 12-16-2000, 05:52 PM
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Re: 2 Problems on rebuilding my Carb

All those adjustments should be covered in the rebuild kit instructions and on the emissions sticker. There are several ways to raise the idle, depending on your exact vehicle: some carbs have a screw; some have a vacuum solenoid; some have an electric solenoid; some are controlled only by the key; some are controlled by a few sensors; some by an EEC. You have to go through the procedures in the kit and on the sticker to get YOUR carb set up right.

BTW "Jet" is a term used only for a carefully calibrated fitting either in the bowl or metering body of a carb that regulates fuel flow into the veturi. They are never in the venturi under the throttle plates. Your kit should have an exploded view of your carb and a list of names for each part. Using those terms will make it much easier to communicate so we will all know what we're discussing.

Good luck.

Steve
83 Custom w/95 4.9L EFI, 78 NP435, 83 NP208, 83 D44IFS 3.07, 87 Ford 8.8ABS 3.08, Michelin LTX AT 31x10.50R15
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