Q&A

Mailbag: Engine-Swap Tips for a Mild-Performance ’85 Chevy Camaro IROC-Z

You’ve got questions. We’ve got answers. We work with the Summit Racing tech department to tackle your automotive-related conundrums. This week, we’re talking about swapping a 350 crate engine into an ’85 IROC-Z Camaro currently powered by a 305 TPI engine.

1985 IROC-Z Camaro

(Image/Pinterest)

Q: I have a 1985 Camaro IROC-Z with a 305 Tuned Port Injection (TPI) engine, 700-R4 transmission, and 3.23 rear axle gears. I plan to buy a 350 crate engine that has been dyno’d at 350 horsepower and 389 foot-pounds of torque with a carburetor.

I was told I could have a custom computer chip burned so I could run TPI fuel injection on the 350. The EFI system will be modified with an Edelbrock High-Flow base manifold and runners, ported stock plenum, 52mm throttle body, bigger injectors, and an adjustable fuel pressure regulator. I will be using 1-5/8-inch headers and a 3-inch dual exhaust.

I would like to get about 350 hp out of the new engine and run in the 13s. Is this possible with my combination?

A: Your crate 350 should be okay for use with a TPI system. We recommend checking the engine’s camshaft specifications. Most “computer-friendly” cam profiles are no bigger than 214-222 degrees duration at .050 and .450-.460 inches of lift with 112-116 degrees of lobe separation. If the cam in the new 350 is much over these figures, you should consider a different camshaft to ensure compatibility with the IROC’s computer.

Your TPI and exhaust modifications should help performance, but don’t get so carried away that you give up everyday reliability. You should be able to hit the 350 hp mark with the computer and custom-burned chip. If you change fuel injectors, start with 22 lb./hr. units and go up only if top-end performance dictates more fuel.

On the exhaust system side, run a 3-in. system only if you have a single pipe from the catalytic converter back. If you have dual pipes from the converter, we recommend using a 2½-in. pipe.

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2 Comments

  1. “” I plan to buy a 350 crate engine that has been dyno’d at 350 horsepower and 389 foot-pounds of torque with a carburetor. “”
    “” I would like to get about 350 hp out of the new engine and run in the 13s. Is this possible with my combination?””
    If the engine has been dynoed at 350 hp,why do you eant to knoewif you can get 350 hp?
    Dumbass…………….

    • OnAllCylinders Staff says:

      Hey Fred, the gentleman’s crate engine was dyno’d with a carburetor to get 350 hp, but he wanted to use the stock TPI (EFI) setup from his Camaro to hopefully get the same results as the original carbureted configuration.

      Typically, when switching from a carburetor to EFI (or vice versa) it can result in different engine hp and torque numbers–tuning and the right parts are required to ensure the engine is running at its best potential.

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