TBI to TPI swap: 91' 305

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Jan 23, 2010 | 07:02 PM
  #1  
How difficult is it to swap out from TBI to TPI? I've got a 91' camaro convertible. Is it worth doing? If so, what combo would be advisable to use? A stock 305 Tpi setup maybe port and polish the manifold and heads, or some aftermarket heads and manifold? Is it a headache computer-wise? Thanks
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Jan 24, 2010 | 06:46 AM
  #2  
Re: TBI to TPI swap: 91' 305
If you are after the 5L TPI's cars power, you need to find a 91-92 donor car and swap transplant harness, computer, TPI, cylinderheads, cam, fuel pump, air intake, full exhast.

In this situation I would look for a 91-92 5.7L donor car and transplant the complete Long block at the same time.
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Jan 24, 2010 | 10:06 AM
  #3  
Re: TBI to TPI swap: 91' 305
I actually have an LT1 sitting on a stand in my garage, but i just had the 305 that's in the car rebuilt. Motor has less than 500 miles on it and I really didn't want to swap the stock block out. Would the heads and other parts off of a 350 fit on my stock 305? If so, what year donor car would i need to look for?
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Jan 24, 2010 | 11:36 AM
  #4  
Re: TBI to TPI swap: 91' 305
As far as the harness goes, you can use the TBI harness and re pin it to TPI by following the link below. I performed this last year and have had no problems with tuning and driveablity. You will just need to get a TPI computer and make sure the Memcal you get is a stock V8. All that is needed is in the thread below.

I did purchase a tool to help me with the repinning process. Although several have used a paperclip to perform this. It only took me a couple hours to do this. Just recheck your work a couple times is all I suggest.

https://www.thirdgen.org/forums/tpi/...d-density.html

As swapping the intake, I beleive there is a tech article on this...
https://www.thirdgen.org/tbitotpi

I didnt do this . I installed the FIRST injection intake on a 383 crate engine when I did this last year. And havnt looked back
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Feb 7, 2017 | 05:36 PM
  #5  
Re: TBI to TPI swap: 91' 305
Hello camaro people! I need some information on tbi to tpi swap.
I have a 305 tbi 89 RS camaro. The tpi system I'm looking at is off a corvette 350. Will it bolt on my 305? Will my factory harness plug n play with the TPI ECU? I just want to swap tbi to tpi with using my factory ecu and harnesses
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Feb 7, 2017 | 05:45 PM
  #6  
Re: TBI to TPI swap: 91' 305
You will need to repin your 1228746 to tpi maf 1227165 86-89 ecm or 90-91 speed density 1227727.
The intake base inner holes need to be elongated to get your heads 72 degree from 90.
You will need the correct 305 Ecm calibrator.
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Feb 7, 2017 | 05:49 PM
  #7  
Re: TBI to TPI swap: 91' 305
Quote: Hello camaro people! I need some information on tbi to tpi swap.
I have a 305 tbi 89 RS camaro. The tpi system I'm looking at is off a corvette 350. Will it bolt on my 305? Will my factory harness plug n play with the TPI ECU? I just want to swap tbi to tpi with using my factory ecu and harnesses
You will be better off going to the 1227730 speed density f-body ecm than doing tpi maf re wire.

https://www.thirdgen.org/forums/tpi/...d-density.html
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Feb 7, 2017 | 07:26 PM
  #8  
Re: TBI to TPI swap: 91' 305
Is it worth the Swap tbi to tpi?
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Feb 8, 2017 | 12:09 AM
  #9  
Re: TBI to TPI swap: 91' 305
In a nutshell, no. The intake manifold isn't the weak link in the TBI 305, it's everything else. TBI cars came with restrictive exhaust manifolds, restrictive Y-pipe, and the same catback as the 6cyls. Not to mention the dished pistons, swirl port heads, tiny cam, shitty gearing...

Swapping just the intake will probably gain a bit of torque, but it won't be as strong as a stock 305 TPI car.
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Feb 8, 2017 | 02:15 PM
  #10  
Re: TBI to TPI swap: 91' 305
Quote: TBI cars came with restrictive exhaust manifolds, restrictive Y-pipe, and the same catback as the 6cyls. Not to mention the dished pistons, swirl port heads, tiny cam, shitty gearing...
But other than that, it's a great little engine!
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