wiring for tpi to carburetor help.
07-10-2004, 06:27 PM
#1
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Join Date: Jul 2003
Location: Warren, Mi
Posts: 114
wiring for tpi to carburetor help.
Putting in a carbureted motor, I need help in the wiring department, what wires do i need to keep and what can i take out. Just bought a 1989 camaro rs 5.0L , If you can help please include the wire colors. Thanks
07-12-2004, 03:07 PM
#2
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Join Date: Dec 1969
Location: Phila., PA
Posts: 1,150
The RS never came with a TPI motor. I assume you mean TBI 305. If so, I just did this swap on my wife's 1992 RS that originally came with the 305 TBI.
Assuming that's the case you really only need a few things connected, hooked up and working for the swap to a carb.
1. Distributor connections. 2 wires- currently plugged into your remote ignition coil mounted on the intake. Bigger pink one and smaller white one- the ones coming out of the wiring harness, not the other 2 that currently go to your distributor. I did the swap to an earlier, non-computer controlled large cap HEI when I swapped to carb, which makes this super-simple. Clip off the factory connector from those 2 wire and splice on some female spade connectors on the wires. Big pink wire goes to the "12V+" terminal on the HEI, white wire goes to the "TACH" terminal on the HEI so your tach still works.
2. Oil pressure sender. Just above the oil filter on the side of your block. 2-wire jobbie. Runs your oil pressure gague and also tells the ECM to keep the fuel pump running. Just unscrew it from the old engine and screw it into the new one in the same place and plug the connector back in when you install the engine.
3. Temp sender for the dash gague. Driver's cylinder head, between the front 2 spark plugs. Same deal- swap it onto the new motor and hook it back up to keep your temp gague functional.
4. Temp switch to run the (single) stock electric cooling fan. Passenger side cylinder head betwen the rear 2 spark plugs. Also swap onto the new engine. Now would be a good opportunity to replace it with an aftermarket lower-temperature fan switch if you want. Stock one kicks on the fan at about 228*. Aftermarket ones are available to turn it on at a lower temp.
5. Ground straps. GM just LOVED to bolt MANY ground straps to the rear of the engine. Where you can't possibly reach them. You'll see what I mean when you go to yank the motor. Real PITA. If you want to make life easier, clip the connectors off them, splice extensions onto them and extend the wires up somewhere you can actually reach them- like an unused bolt-hole on the intake manifold, for instance. Remember to do this for ALL the ground straps. I think there are 5 or 6 in total, if memory serves. ALL must be grounded onto the new motor in some way, however you choose to do it.
6. Starter connections- they'll all be the same. Put them back on the new engine's starter in the same position they came off the old starter. Basically 1 of the wires goes to the small start terminal and everything else goes onto the large main battery terminal. It would be difficult to mix them up since they have different sized ring connectors on the end so it should be obvious which post they go on.
7. There's one wire that came from the front passenger corner of my engine's wiring harness to the power distribution block near the battery. Had to be disconnected to get the engine out but went right back to where it came from when the new engine went in.
EVERYTHING else gets unplugged and never used again. Injectors, IAC, IAT, MAP, EGR, EGR solenoid, TPS, CTS, smog pump diverter valve connections, etc. All unused. Mine are currently just laying around the engine bay in any places I can find to tuck them. I'll pretty it up later.
I also ditched my stock heater core diverter valve and it's miles of coolant hoses for a much simpler 2-hose system that simply goes from the intake manifold to the heater core and back up to the radiator (viz the stock metal line on the pass. frame rail). Kinda like they used to run them back decades ago. Really cleans up the engine bay.
My fuel system still uses the stock in-tank TBI fuel pump, still run by the stock ECM (that's the ECM's only job now, besides running my speedometer). I use a Mallory 3-port return-style regulator to bring the electric pump's pressure down to a more carb-friendly 6 PSI. I have it patched into the stock lines, mounted over on the driver's side inner fender. Very simple install and it works beautifully. Holds pressure perfectly.
All the gagues still work, even the A/C still works just like it used to! Aside from the "check engine" light being on all the time (haven't yanked the bulb yet) you wouldn't know the ECM wasn't running the show any more. Your lock-up torque converter won't lock up any more if you have an automatic trans so be aware of that- this can overheat an automatic trans if you don't install a big trans cooler or buy an aftermarket stand-alone kit to activate the lockup mechanism in the converter.
Assuming that's the case you really only need a few things connected, hooked up and working for the swap to a carb.
1. Distributor connections. 2 wires- currently plugged into your remote ignition coil mounted on the intake. Bigger pink one and smaller white one- the ones coming out of the wiring harness, not the other 2 that currently go to your distributor. I did the swap to an earlier, non-computer controlled large cap HEI when I swapped to carb, which makes this super-simple. Clip off the factory connector from those 2 wire and splice on some female spade connectors on the wires. Big pink wire goes to the "12V+" terminal on the HEI, white wire goes to the "TACH" terminal on the HEI so your tach still works.
2. Oil pressure sender. Just above the oil filter on the side of your block. 2-wire jobbie. Runs your oil pressure gague and also tells the ECM to keep the fuel pump running. Just unscrew it from the old engine and screw it into the new one in the same place and plug the connector back in when you install the engine.
3. Temp sender for the dash gague. Driver's cylinder head, between the front 2 spark plugs. Same deal- swap it onto the new motor and hook it back up to keep your temp gague functional.
4. Temp switch to run the (single) stock electric cooling fan. Passenger side cylinder head betwen the rear 2 spark plugs. Also swap onto the new engine. Now would be a good opportunity to replace it with an aftermarket lower-temperature fan switch if you want. Stock one kicks on the fan at about 228*. Aftermarket ones are available to turn it on at a lower temp.
5. Ground straps. GM just LOVED to bolt MANY ground straps to the rear of the engine. Where you can't possibly reach them. You'll see what I mean when you go to yank the motor. Real PITA. If you want to make life easier, clip the connectors off them, splice extensions onto them and extend the wires up somewhere you can actually reach them- like an unused bolt-hole on the intake manifold, for instance. Remember to do this for ALL the ground straps. I think there are 5 or 6 in total, if memory serves. ALL must be grounded onto the new motor in some way, however you choose to do it.
6. Starter connections- they'll all be the same. Put them back on the new engine's starter in the same position they came off the old starter. Basically 1 of the wires goes to the small start terminal and everything else goes onto the large main battery terminal. It would be difficult to mix them up since they have different sized ring connectors on the end so it should be obvious which post they go on.
7. There's one wire that came from the front passenger corner of my engine's wiring harness to the power distribution block near the battery. Had to be disconnected to get the engine out but went right back to where it came from when the new engine went in.
EVERYTHING else gets unplugged and never used again. Injectors, IAC, IAT, MAP, EGR, EGR solenoid, TPS, CTS, smog pump diverter valve connections, etc. All unused. Mine are currently just laying around the engine bay in any places I can find to tuck them. I'll pretty it up later.
I also ditched my stock heater core diverter valve and it's miles of coolant hoses for a much simpler 2-hose system that simply goes from the intake manifold to the heater core and back up to the radiator (viz the stock metal line on the pass. frame rail). Kinda like they used to run them back decades ago. Really cleans up the engine bay.
My fuel system still uses the stock in-tank TBI fuel pump, still run by the stock ECM (that's the ECM's only job now, besides running my speedometer). I use a Mallory 3-port return-style regulator to bring the electric pump's pressure down to a more carb-friendly 6 PSI. I have it patched into the stock lines, mounted over on the driver's side inner fender. Very simple install and it works beautifully. Holds pressure perfectly.
All the gagues still work, even the A/C still works just like it used to! Aside from the "check engine" light being on all the time (haven't yanked the bulb yet) you wouldn't know the ECM wasn't running the show any more. Your lock-up torque converter won't lock up any more if you have an automatic trans so be aware of that- this can overheat an automatic trans if you don't install a big trans cooler or buy an aftermarket stand-alone kit to activate the lockup mechanism in the converter.
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