Want to replace variable venturi carb with 4bl carb

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Mar 20, 2003 | 07:45 PM

RAW_Bronco

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Want to replace variable venturi carb with 4bl carb

I have an '83 Bronco with a 351W and the Duraspark III ignition system which uses the EEC III computer to determine ignition timing. I want to put a normal Holley 600 CFM carb with elec choke on the motor. I have the carb and an intake manifold, are there any computer problems with this swop?

Does the EEC III use any sensor information from the variable venturi carb?

Any help would be greatly appriciated (other than spelling, I already know I can't spell or type).

Thanks

Mar 20, 2003 | 09:36 PM

thelonerangerxlt

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Want to replace variable venturi carb with 4bl carb

I did this swap on a Bronco II a while back. There is a throttle position sensor (TPS) on the V V Carb, that the computer takes a signal from. I'm not sure if the TPS signal is also used for timing, or just for the carb adjustment. On the Bronco II, I replaced the carb and distributor at the same time, and disabled the computer. I used a Mallory distributor, which was a stand-alone unit, and didn't require any external input.

If it were mine, I would try it first with the ECC III distributor and computer. It may run fine. If you find that the timing won't advance properly, then you can change distributors; either to an aftermarket or possibly a Duraspark conversion.

Good luck with it.

Mar 20, 2003 | 09:50 PM

RAW_Bronco

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Want to replace variable venturi carb with 4bl carb

Thanks for the info. I would think the EEC III would use the TPS to help determine the load on the motor. Don't know though. I had thought about also replacing the distributor with a stand alone. I just didn't want to spend the money if I could avoid it.

Thanks Again

Mar 21, 2003 | 09:41 AM

thelonerangerxlt

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Want to replace variable venturi carb with 4bl carb

RawBronco, you're probably right about the EEC III needing a TPS input. The distributor dosen't have a vacuum advance cannister, and there has to be a manifold vacuum input from somewhere. I don't remember if the EEC III has a MAP sensor or not. If it does, it'll be a small box-like sensor mounted on the firewall, with a vacuum hose going into it and an electrical plug-in.

Maybe you can adapt the TPS to your new carb......??? It's just a variable resistor that gives a signal from about 1v to 4v, depending on the throttle position. There may be a way to modify the new carb linkage to work the TPS?????