Switching from TBI to Carb, what am I up against?
#1
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Car: 1991 Camaro RS and 1992 Camaro RS
Engine: 305 soon to be a 383 or 427 SBC
Transmission: T5 and 700R4 soon to be ?
Axle/Gears: Stock...
Switching from TBI to Carb, what am I up against?
Hi and thanks. I am seriously thinking of switching from the TBI on my 1991 RS, 305 V8 and 5 speed manual to a carburetor. Not exactly sure where I would go and what I can remove from the engine bay to make this happen. The VAT system is driving me nuts. I have the starter relay bypassed, but of course you need a signal from the ECM to fire the injectors and make it run. The resistor bypass only worked for a couple months. I figure with a carb the ECM and VATs becomes obsolete as you can wire the fuel pump to run as needed with a pressure regulator.
Please let me know if what I am doing makes sense.
Thanks.
Please let me know if what I am doing makes sense.
Thanks.
#2
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Re: Switching from TBI to Carb, what am I up against?
Ive been running one of those $20 ebay VATS bypass for 2 years without an issue. It doesn't use a resistor tuned to the original key. It just sends the signal the ECM is looking for.
A lot simplier then a tbi to carb swap, if that is the only issue you are having.
A lot simplier then a tbi to carb swap, if that is the only issue you are having.
Last edited by 3rdgenmaro; 11-15-2016 at 09:20 AM.
#4
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Re: Switching from TBI to Carb, what am I up against?
I wouldn't call it a resistor........its a signal generator I guess.
Price has went up, but this is what Ive been running. Just splice it in and go. $20 shipped http://www.ebay.com/itm/GM-VATS-or-P...1WEYiu&vxp=mtr
Havent had any issues so far.
All you have to do is wire it in and bypass the starter relay (which the OP has already done)
EDIT: I know it works on my 91 TBI. I don't even have the key cylinder in the car, just the ignition switch, and so far no issues. I installed it because I had a couple no start problems because of the VATS.
Price has went up, but this is what Ive been running. Just splice it in and go. $20 shipped http://www.ebay.com/itm/GM-VATS-or-P...1WEYiu&vxp=mtr
Havent had any issues so far.
All you have to do is wire it in and bypass the starter relay (which the OP has already done)
EDIT: I know it works on my 91 TBI. I don't even have the key cylinder in the car, just the ignition switch, and so far no issues. I installed it because I had a couple no start problems because of the VATS.
Last edited by 3rdgenmaro; 11-15-2016 at 09:22 AM.
#5
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Re: Switching from TBI to Carb, what am I up against?
I have also used this exact VATS bypass module in my build. Really simple to wire in. This was on a '91 TPI car, but it should work on anything that has VATS (and a passkey module).
The only issue I had was trial and error to determine whether I needed a 30Hz or 50Hz signal. I wound up trying the wrong one first, of course.
The only issue I had was trial and error to determine whether I needed a 30Hz or 50Hz signal. I wound up trying the wrong one first, of course.
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Car: 1991 Camaro RS and 1992 Camaro RS
Engine: 305 soon to be a 383 or 427 SBC
Transmission: T5 and 700R4 soon to be ?
Axle/Gears: Stock...
Re: Switching from TBI to Carb, what am I up against?
I got as hold of Brain at Harris Performance and he said to send him my stock chip and he will delete the VAT system off the chip. I will give this a try and let you all know. I hope it's $60.00 well spent for a little bit of confidence in the car. www.tbichips.com
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Car: '86 Camaro, '94 Camaro, 3 others
Engine: LG4 ->L29, L32->LR4, L36, LG4, L31
Transmission: 700R-4, T5WC, 4L80E, SM465, 4L60E
Axle/Gears: 3.42, 3.23, WTB/WTT 2.93
Re: Switching from TBI to Carb, what am I up against?
I have had the VATS proble, trying resistors from Radio Shack was the solution. Cheap, only took a couple of hours.
I have converted an LO3 from TBI to carb, don't do that. I just posted a new thread in TBI about that, go read it.
I have converted an LO3 from TBI to carb, don't do that. I just posted a new thread in TBI about that, go read it.
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Car: 1991 Camaro RS and 1992 Camaro RS
Engine: 305 soon to be a 383 or 427 SBC
Transmission: T5 and 700R4 soon to be ?
Axle/Gears: Stock...
Re: Switching from TBI to Carb, what am I up against?
Thanks Cosmic. I am eagerly awaiting my re-programmed chip that eliminates the VATs completely.
#11
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Car: 1991 Camaro RS and 1992 Camaro RS
Engine: 305 soon to be a 383 or 427 SBC
Transmission: T5 and 700R4 soon to be ?
Axle/Gears: Stock...
Re: Switching from TBI to Carb, what am I up against?
Installed the reprogrammed chip today and the car started right without any issues. The security light is on permanently so I will need to find the bulb/wire and remedy that problem. Now it's on to other projects on the car.