Hello all. I have a few questions. I am in the process of gathering parts for my TPI swap. The parts are going on a pre-86 SBC (383). I have found a TPI setup for a decent price, but it is for an 89 305 complete with distributor, sensors, harness, & ECU. I know that I will either need to get a pre-86 base or modify the post 87 base. I am also aware that I will need to get bigger injectors.

My questions are

1. If I get a pre-86 base, will the 87 & up sensors, emissions, etc work with the older base? Or, do I need to get all new equipment to make it work?

2. Since the TPI setup is for a 305, do I need to get a different ECU or can this one be retuned to support more fuel, spark, etc? Can this be accomplished with a simple chip swap?

3. What size is the stock throttle body (air inlet)? I have seen larger 52mm & 58mm TB's. Do you all recommend a larger TB to support the engine, or would the stock unit suffice?

4. I have been reading around about knock sensors possibly having problems with gear drives. My engine has the quiet Pete Jackson gear drive (which I would like to keep). Would a LT4 knock sensor solve my problems or is there another route that I should go?

5. Lastly, do you all think it would be cheaper to just find a 350 TPI setup instead of modifying the 305 setup? The guy wants $175 for it, but I would at least need to get bigger injectors if nothing else.

The setup is going on a pre-86 383 with world heads, mild crower cam, full roller rockers, quiet gear drive and 9.5:1 compression. All of this is going in my 92 Chevy Silverado short cab, short box, 2wd. That being said, torque is my goal since the truck weighs 4k lbs without me in it. Also the truck needs to pass emissions and I would like it to get decent gas mileage. It is not a daily driver, but I would like to be reliable enough to be one if needed. That being said, I would like to keep most of the sensors on the system.

Thanks in advance for all the help. If yall can think of something that I over looked, please feel free. I greatly appreciate it.

Thanks.

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1. The newer sensor will fit the older base. The on caveat is that the older base will be configured for a cold start injector, and IIRC 1989-later TPI systems did not use the cold start. You will have to find something to fill the hole, whether it's a cold start injector or plug. Either way, the runners and plenum will have to match the base, since there are two designs (three if you count Corvettes).

2. The ECM is the same for the 305 or 350. The differences are the CALPAK and programming, and the ESC and knock sensor.

3. The stock throttle body is a twin 48mm bore size. It can support up to 505HP. A larger TB would not be on my list of first modifications.

4. If you plan to use a gear drive, you will likely have trouble with false detonation inputs. You could use the 350 knock sensor to reduce sensitivity somewhat.

5. That all depends on the price of the 350 TPI system.

 

good job in aswering all the questions vader

for question #4,
i could have heard wrong but i thought that the LT4 knock was more fitted to performace applications.
and for #5
i dont think it would really mater weither it was a 305 or 350 because you still need a new tune. so the price diff wouldnt mater. anyway it would be a good idea to replace those sensors due to the age of the intake.

later,
Mike

 

Good deal. Thanks for all the input. I also went out and bought the TPI swappers guide yesterday and found quite a bit of useful info as well. This will go a long way towards designing a system that will not only last, but perform for years to come, along with getting decent gas mileage and passing emissions. This way I shouldn't have any problems to pop up along the way.

I also have an LT1 intake, fuel rails, and injectors laying around. Eventually I would like to get it machined to on this 1st gen engine. According to sites like LT1intake.com, the LT1 intake can be used with the TPI sensors and wiring and the installation is pretty much plug & play with the exception of the remote mount t-stat. But that is a ways down the road.

The intake is from a 97 Camaro SS. Could the injectors on this 97 LT1 work on the TPI? I ask this because I would need bigger injectors anyway.

Thanks again for all yall's help. I am reading thru the swappers guide before I start the install so I can try to have things planned out. If I have any more questions, I will be sure to let yall know. Thanks.

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