Looking for information/advice. I have a 1987 Iroc-z. The car had a 350 TPI in it. The motor blew a long time back and car has been sitting for a long time. The old engine was pulle out when it blew and I no longer have any of the TPI intake from the old engine and anything I do have is no longer usable. I am trying to get it back on the road and I'm faced with two options. Option 1: buy a used TPI engine that is complete but has the possibility of having over 100k miles on it for about 1500$ or Option 2: switch to a carb engine and buy a new one complete for like 2500-3000$ but have a warranty and all. I would rather have a new engine obviously but will it be difficult to switch from TPI to carbureted? Is it going to cost me more money in switching? I am not going to be doing it I'm gonna be having a mechanic do all the work just because I want to get it done as soon as possible and correctly. Any information would be great. Thanks. Oh also. The car had a 700r4 trans in it. Worked fine when the engine blew. Think it's still good? Same goes for the rear?


Reno.

 

The main issues are fuel supply and TH700R-4 TCC lock-up.

The fuel issue can be managed by using a return-type fuel pressure regulator to drop the fuel pressure to a carb-friendly 4-6 psi. It has to be a return-type to keep the in-tank fuel pump alive (it needs constant flow to keep it from overheating - a cheap dead-head regulator will kill it).

TCC lock-up can be handled by a kit, or if your mechanic is clever enough, rewiring inside the transmission pan. You may want to get a kit for him.

A few other details are throttle cable lengths (both the accelerator cable and the TV cable for the TH700R-4), and getting a "geometry corrector" bracket for the TV cable on the carb throttle arm. Radiator hoses are different between TPI and carb, but that probably isn't an issue because they likely aren't there anymore.

Hope your mechanic is a patient guy.

 

I recently did this but I had a tpi car and a carb parts car. Having the under hood harness and carb car tank made it much more simple.

 

They make special intakes for some lt1 third gen heads http://www.chevytalk.org/fusionbb/sh...hp?tid/193397/

 

Ok thank you for all the information. In your opinions do you think it's even worth it to swap it to a carb or should I just buy the less expensive TPI motor from HawksThirdGen and have the mechanic install that motor not really have to but a lot of time into it?

So just an update I decided to go with the Hawks route. I talked to them and they happened to have a totaled 87 trans am with 98k original miles on the drivetrain. So I ended up buying the whole drivetrain with harness and computer. I'm hoping that this will be the route with the least amount of headaches. I'm really excited to get it back up and running.

 

In my opinion it depends on if you want fuel injection or carburation. The Carb is nice bolt on and go because you dont have to get the computer tuned unlike the TPI when you decide to run larger injectors and throttle body.But fuel injection is more throttle responsive they say when you dial it in, but I eliminated the headache and went to a nice carburetor 4bbl with that intake i sent you in the link. I was having problems with electrical in the computer then and the 1985 problematic gm distributor module failed. Im dropping in a HEI distributer now, 750 carb and intake i have a 383 stroker in my 85' camaro iroc. I had the TPI in the car, it was built by a engine builder, and when driven it made the car pull really hard was nice. I was running the BBK power plus throttle body 52mm size and pontiac v6 30lb injectors, rochester fuel rails, k&n intake. Just got to dial in the TPI.

 

So just a question about the Fuel Regulator, I have just joined on here. It has to be a return Regulator correct? I have a good one but not sure if it is a return Regulator. Thanks

 

I'm going down the same path right now....pulled and sold the crap 305. Now trying to remove the wiring harness in the engine bay along with everything else so I can weld up holes, prep and paint.

I plan on dropping in a carb 350 that I'm in the process of rebuilding. The fuel supply and return were my biggest question.

Any advice on how to get this harness out? I really don't care for any of it as I plan to build this car as a streetable toy and just need to make sure all the lights work.

 

I pulled the ECU, engine control unit, out with all of it's wires. that took care of the engine wire harness and all the sensors. There are 2 plug in's on the fire wall. The right one is the engine harness the left one is the lights, heating fan Ac, etc. Leave that one. Just undo the bolt and remove the one on the right. That is the engine harness connector. I had a company build me a harness to fit a 1980 Camaro. It came with a different style plug in but I removed the wires and got new ends and used a wire schematic for what the new harness came with and put it back together. I used the Fuel pump plug in and the 4th gear lock up plug in. you will have 2 wires you won't need in the new harness if you go that route and use them for the 4th gear lock-up and OEM fuel pump supply that's in the tank. it has to be able to work in the key start on position. Also make sure you get a return style regulator. I got a regulator but it's not a return style. The fuel pump will heat up if there is no return line going back to it. Any other questions feel free to ask.

 

Just yesterday I found the proper fuel regulator to use.

 

to any of you guys doing the swap... is there a 3 prong plugin on the tpi harness to plug the HEI distributor into? i know i have to put connectors on the tach and coil wires to hook up to the coil. but what connection do i have to make on the distributor itself?


edit: nvm i got it

 

I am also in the process of putting a carbed lt1 with msd dist and box, in a 88 Trans am, 305 tpi, 700r4. Have made it through the engine bay rewire / ecu and have a running, key start setup. used all the earlier wiring threads listed here. My question concerns the double plug (c207?) in the interior that plugs into the ecu harness. If I'm correct, the majority (all but 3 or 4) deal with the aldl tester, which is of little value without the ecu input? I haven't verified all wiring connections in the interior yet, but have a few gremlins. Should ecu remain for interior plug, even if wires are cut/removed for engine bay?
Sorry for long thread, but haven't been able to find anything specific
thanks for any help

 

Anyone know why my fuel pressure gauge decreases as the engine warms up?

 

Electric fuel pump? If yes, it could be a few different things. I would look at your charging system first and make sure the voltage isn't dropping as the car warms up and the fans kick on. It could also be the pump just getting old and needing replaced.

 

I have the 305 TPI and would like to install a crate motor, but I'm not sure what to do with the return fuel line and pressure reg? Should I go mechanical fuel pump and disconnect the electric pump? Or should I keep the electric fuel pump and install a block off plate over the mech pump hole? Again if I go mechanical, what do I do with the return line and pressure reg? Any suggestions are welcome. Thanks...Joe

 

Hey Joe, I'd go with what you already have. Leave your pump in the tank... get a block off plate, pressure regulator (I went with aeromotive, kind of expensive) and you'll need the fittings for the fuel lines to the regulator. Fittings are cheap. You can find the thread size if you search hard enough.

You'll need a return style regulator. The return line and the supply line are different thread sizes.

 

Hi 802maro, does your holly carb have a single or duel fuel inlet? And if so how did you plump it?? I'm not sure how to connect the return fuel line. Thanks...Joe

 

Feed it plenty and you'll plump it just fine lol...

Joe, the fuel regulator will show you which ports are for the feed and for the return in the directions, it is very easy to do. You just need the correct sized (and length) braided fuel lines and adapters. The TPI lines use saginaw fittings, and the connector adapters to fasten to them are expensive. Can get them from Earl's Plumbing Performance. Just make sure you go with a regulator designed specifically to lower fuel pressure down from 43.5psi to 5-psi for the carb setup. The stock fuel pump can be triggered via the fuel pump relay and a switched 12 volt source. Easy. HTH...

 

Sorry I meant to say," how did you plumb it"? Not plump it. Any way, I'm curious how the carb versions of the Z-28's were set up? As you know the carb versions came first. Did they come with a press reg and return line as well??