hjsmith00843

I will be converting to a carb with a Eledebrock intake from my current TBI unit.

I will also be changing out the current fire system with the larger HEI system.

What should I look for during this conversion. From what i was told it has a 350 and not a 305 in it. Will try to confirm this soon.

five7kid

iTrader: (14)

The basic issues, beyond the parts needed for the carb and intake, are:

Fuel delivery:
Need a return-type regulator if keeping in-tank electric pump. Need to remove in-tank electric pump if using an engine-mounted mechanical pump. I'd recommend going the regulator route.

If auto transmission:
TV cable geometry corrector bracket for the carb throttle arm
Some means to lock up the torque converter clutch

The pink power wire and white tach wire that currently go to the coil will have to be connected to the HEI "BATT" and "TACH" terminals (by "larger", I assume you mean a coil-in-cap type HEI distributor). You could get a small cap vacuum/mechanical distributor and keep the factory coil. Most people go with the coil-in-cap distributor.

This isn't emissions legal in any of the 50 United States. If you don't drive it on the street, or don't live in the U.S., that's probably not an issue.

For sure check on the "350" thing. I'd guess something in the neighborhood of half of the "350" 3rd gens sold have a 305 in them.

bestracing

Isn't that the truth. My brother and I went to buy an 86 IROC shell for parts and the guy that sold us the car said he pulled the "350 motor and trans" out of it. I got a look at it and showed him that it wasn't a 350 instead it was a 305 (5.0L on the block). He was very disappointed.

hawthor

im doing this same swap in my 90 rs it seems to me that there is not 2 wire harnesses it all goes togather and splits to both side of the car just wondering what to do dont wana butcher the wiring but most of it will not be used any help would be great thanks

bestracing

There should be 3.

Two come from the driver side, out of the firewall. It's one pass through connector and splits into two harnesses, One for the motor and the other for the lights. The other harness comes from the passenger side from between the fender and the side of the firewall. This is the computer harness. Now I haven't worked on a 90 but I have worked on an 89 and it was the way I described (Installed a 355 L98 motor). If you had a big enough loom to cover both bundles then I guess you could make it look like one continuous harness but I haven't seen any like this.

One thing about later f-bodies especially T/A's is that they have electronic driven speedometers. If you remove the ECM harness all together then you will have to remove the speedo sensor cable from the ECM harness (both inside and out side portion). This is the yellow and purple wire going to the transmission tailshaft. You will also have to run a ground wire to the pulse control module that is mounted to the side of the ECM bracket. I did this with my 86 T/A.

my3rd

so what if I put on a carb, vac advance distributor, and keep all wires/ plugs/sensors? I know most don't function but will I be able to still have electric Speedo, fans pump etc? I just want to see how much of any performance gains I get but also be able to swap back to tbi if I want with ease...


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my3rd

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onemanarmy41

Depending of the carburetor available(mine s a holley 2 barrel 8450 from a 79 dodge ramcharger with a 360 engine) the aluminum adapter plate is made, I used the mounting gasket from the rebuild kit as a template , the adapter plate is made out of 1/2" aluminum then the carburetor bolts are drilled and tapped
there was enough clearance for the carburetor barrels to open without touching the intake when opened all the way one hole is drilled thru the plate to attach it to the original intake hole I used a bigger bit and an allen head bolt to make sure is flat on the adapter plate surface, the rest of the install requires epoxy all the way around were the adapter plate makes contact with the original intake leave it overnight to cure and presto

this is what my 88 k1500 looks like now, for the fuel pressure conversion(the original pump puts out 13 pds of pressure a carb would hold of to 9pds of pressure) I left the original pump in and used a Cadillac CTS fuel filter under he hood this filter has 3 lines to it in out and return, so I installed the input line in by the carb the return line bythe carb also)previously they would go behind the tbi and then he output line was hooked up to the carb NO PRESSURE REGULATOR NEEDED) since this filter has a return line all the extra pressure would just return to the tank and would not affect the carburetor.
a hei distributor from a 76 chevy truck was used and THE WIRING HARNESS WAS NOT CUT just tape it correctly and tuck it away on top of the manifold THATS ALL YOU MADE IT CARBURATED NOW!!!!!!!!!!!!!!

midias

Why are you bumping random threads that are 5 years old?