Hi all. I'm a 3rd gen novice here. I have a '91 Z28 convertible with a blown 305 TPI. I've purchased a wrecked '91 GTA with a running 350 TPI that i'd like to throw into the '91 Z28. I believe it to be a straight swap as far as I can tell. I was just planning to pull the motor and computer, complete from the GTA and drop it into the Z28. From the research I've done, it should be a plug and play swap. Can someone help with pointing out some of the issues with doing such a swap?

I was also going to swap the transmissions at the same time, as well as the rear end. I'm hoping some of the experts here on this forum can give me some tips on everything.
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Thanks in advance!!!

 

Should be a pretty straightforward swap. I'm assuming both cars are automatics. Engine wiring harnesses should be the same between both cars. You could just swap the PROM chips in the ECM, or swap the whole ECM. Either way should work. Leave the knock sensor and fuel injectors in the 350 when you swap it over.

The Z28 convertible should have the small outlet exhaust manifolds, 2.25" y-pipe, single 2.25" converter and cat back. The large outlet manifolds on the 350TPI won't bolt up to the 2.25" y-pipe, so you will either need to swap the exhaust manifolds and use the small exhaust from the Z28 (not recommended since it's so restrictive), or swap the whole exhaust system from the GTA (should have the dual cat y-pipe and 2.75" cat back exhaust).

Transmissions between the two cars should be the same, so pick the best one between the two and use that one. The rear end from the GTA is either a 9-bolt with 3.27 gears or a 10 bolt with 3.23 gears (don't recall when they changed back to 10 bolts), posi and disc brakes. The Z28 convertible would be a 2.73 (if an automatic) so would be worth swapping. If the Z28 already has disc brakes in the rear, then you're good. If it has drums, then you will need to swap the master cylinder and proportioning valve over from the GTA. Also speedometer gears in the transmission. If you swap both the transmission and rear end, then it's fine. If you swap only one or the other, then you'll have to swap the speedo gears to match the rear end gear ratio.

That's all I can think of. Good luck with the project.

 

Hello TransamGTA350. Thank you so much for the response, and the information. I greatly appreciate it!!! Thanks for confirming my thoughts about the engine swap, and the additional information on other parts. I hope the swaps go as smoothly as we think.

Have a great 2023!!!