I'm considering installing an L69 engine form a 1986 Monte Carlo SS in my 1986 IROC. The original engine in the IROC is the LG4. This is a manual transmission car. The IROC has 90,000 miles but is very clean. The original engine over heated and the head gaskets blew that's why I have decided to replace it.

I do have a couple of questions that I hope someone can answer for me.

1. Why is the Monte SS L69 rated at only 180 hp when the Camaro L69 is rated at around 190 hp?

2. Will there be a problem if I replace the Camaro ecm and engine harness with the Monte Carlo ecm and engine harness since the IROC is a manual transmission car? Will all the gauges function if I do so?

3. Does anyone see this swap as being a major problem?

 

That'll be a super easy swap.

The monte may have had a slightly different air cleaner, or exhaust, I forget. But that 10HP is moot now. I'd throw in a cam and headers on it and gain 30HP and forget about that 10HP.

 

What kind of cam would you recommend?

I already have the dual snorkle air cleaner.

 

the xe256he from comp is a tried tested and true firebreather upgrade for an L69. Grinning ear to ear type of upgrade.
Since you have the 5 speed, (and 3.73 gears) if you're willing to "go big or go home" the xe262he is also a very good choice.

Look at headers first though, FYI.