1988 c3500 350 tbi


Old 03-18-02, 09:12 AM
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change 350 TBI to carb

1988 C3500 4 speed manual, was 454, changed to 350 TBI with wiring and sensors cobbled up by previous owners. Can I put an old carb intake (hog out center bolt holes ?) carb, fuel regulator, and HEI dist on this motor? Will gauges (fuel, oil, temp, speed) still work ?

I have parts to change over and there is no state inspection.

Last edited by tbc; 03-18-02 at 09:47 AM.
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Old 03-18-02, 11:03 AM
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No. It's a bad idea.

The truck will use more fuel, be slower, fail emissions and be a general pig .

Sounds like a put together, I agree. Put the right 454 back in there so it will run and haul right. Someone's bright idea of putting a 350 in a truck with a 454 was the wrong one. It's actually WORSE now .

States without inspection programs can still stop you for emitting too much pollutant and if they don't have inspections they likely will soon if they want federal money for programs, so it's a matter of time.

If it's really hokey, pitch the truck for something that has had less hands in it. Better off now than to undo all the previous "handywork".
Old 03-18-02, 02:27 PM
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Old 03-18-02, 02:46 PM
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posting problems tired of typing

can carb intake fit ????

will computer without dist input work gauges right
Old 03-18-02, 03:34 PM
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It can be done, but its a lot of work.

You will have to change the gas tank or you might be able to find a non Fuel injection style pickup tube and sending unit for the fuel tank( the fuel pump is in the tank on the FI models) to high pressure for the carb.

I would suggest getting a aftermarket intake manifold though and a Holley carb to match(You this Marturo!), probably about 700cfm.

HEI will work with a 12v power source.

Oil gauge I'm not sure about, I think it will be ok though(don't think it runs through the ecm)

Temperature gauge will be ok.

Good Luck

If I had a choice though, I would put back the BB 454 and set it up like it is supposed to, but that is what America is about.

You asked can it be done, not is it a Good idea...
Old 03-18-02, 04:21 PM
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454 long gone, wiring and sensors muffed up

have carb, intake, hei

if intake will fit then just use regulator to drop pressure

big questions is if computer has no distributor input after switching to HEI will gauges work ( diagrams show all gauges from computer )
Old 03-18-02, 04:23 PM
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No problem with your plan, you got to deal with what you have

Good luck
Old 03-19-02, 06:28 AM
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As Chad and I said, if you want to, more power to you .

It's a large headache to convert a computer command and fuel injected car to old time controls. Not to mention it will not likely yield desireable results .

Is the truck in good shape and perhaps warrants the right motor and controls back to original? If not, might want to swap it for something better.

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