1987 Monte Carlo SS Aero Coupe Gen5 Build

[mlangkamp]

Hey all, new to the forum and looking for some advice on my build.

I have a 1987 Monte Carlo SS Aero Coupe that I've had since 1990. I bought it wrecked. It was hit in the front right corner. When I put it back together in '90 I had to have the frame straightened and its never been 100%. So last fall I purchased a burnt 1988 Monte with a great frame. I now have that sandblasted, painted and ready to go. A few months ago I bought a 7K mile LT1 out of '18 Camaro with the 8L90 behind it. I'm getting ready to start the build this weekend. I have a UMI Stage 2.5 kit with coil overs, a Ford 9" rear end, Wilwood 4 piston in the rear and 6 piston in the front. The plan is to build a roller before pulling the body off the old chassis. Its a 56k mile car so its still pretty solid (except for the floor pan of course).

A couple questions about the LT1 thought....are guys still running O2 sensors or are they being programmed out of it? And if they are running them, how many? I'm quite new to the Gen5 LT world so I'm still learning. I've found a set of headers that have the port but just not sure what to do here. For now I would like to keep the motor as factory as possible.

Next question is about the cooling package. Are guys running oil coolers and/or tranny coolers? And if so, inside the radiator or separate units?



And lastly, has anyone had any experience with the 8L90 in a G-body? Just wondering about the fit.

Thanks in advance!

[andrewb70]

Hey all, new to the forum and looking for some advice on my build.

I have a 1987 Monte Carlo SS Aero Coupe that I've had since 1990. I bought it wrecked. It was hit in the front right corner. When I put it back together in '90 I had to have the frame straightened and its never been 100%. So last fall I purchased a burnt 1988 Monte with a great frame. I now have that sandblasted, painted and ready to go. A few months ago I bought a 7K mile LT1 out of '18 Camaro with the 8L90 behind it. I'm getting ready to start the build this weekend. I have a UMI Stage 2.5 kit with coil overs, a Ford 9" rear end, Wilwood 4 piston in the rear and 6 piston in the front. The plan is to build a roller before pulling the body off the old chassis. Its a 56k mile car so its still pretty solid (except for the floor pan of course).

A couple questions about the LT1 thought....are guys still running O2 sensors or are they being programmed out of it? And if they are running them, how many? I'm quite new to the Gen5 LT world so I'm still learning. I've found a set of headers that have the port but just not sure what to do here. For now I would like to keep the motor as factory as possible.

Next question is about the cooling package. Are guys running oil coolers and/or tranny coolers? And if so, inside the radiator or separate units?

And lastly, has anyone had any experience with the 8L90 in a G-body? Just wondering about the fit.

Thanks in advance!

Sounds like a cool project, especially with the Gen 5 engine!

My guess is that just like with the earlier OEM systems the rear O2 sensors are deactivated and only the pre-cat sensors are being used. Not sure about the trans, but they are huge and not likely to fit.

Andrew

[Vimes]

Sounds like a great project. I had an 84 Olds Cutlass many moons ago that I wish I still had, and it was a comfortable, reasonably fast car (for a V6) that was perfect for my then-young family.

The front O2 sensors are absolutely required. The rears can be programmed out, although the computer supposedly uses them for fine tuning on the fuel/air mix instead of just squealing on you for hollowing out the cats like the early rear O2s did. I've never noticed a difference though. I'd also at least run racing cats because they do clean the air, and eliminate the smell of fuel and oil in the exhaust.

On the oil and trans cooler, you want to run the in-radiator trans cooler at a minimum. Without it, your transmission will die very fast. An oil cooler isn't a requirement, as the engine has water being pumped through it, but an oil cooler will help if you do any kind of racing, and I can't imagine you'd be doing all this without planning to race. The Monte SS with the 305 was surprisingly fast from the factory. If you run an aux trans cooler, you'll want that before the rad cooler. Transmissions like their fluid to be at a set temperature, and if the aux cooler cools it down too much the rad cooler will warm it back up. If the fluid is too hot the trans dies, but if it's too cold it's also too thick, and the trans has a hard time pushing it around. Some cars even have thermal bypasses on the trans cooler that won't allow fluid through the cooler if it's too cold.

Speaking of the trans, the 8Ls are notorious for having shifting problems. Last I heard, GM released a new fluid for them that is supposed to have solved the problem. That stuff is pricey though, something like 10-12 bucks a quart. I don't know the part number, but it's Mobil One trans fluid, and a little internet surfing will turn up what you need.

[mlangkamp]

We mocked up the rear end, welded the mounting brackets for the could overs, and welded some ears to mount the brake lines. We then removed it and painted it. Tomorrow we will install the rear end, axles, brakes, and wheels and make it roll. Headers and motor mounts are ordered!

As for the 8L90, we plan to try measuring clearances with the old car between the floor pan and tyranny, then remove the body, measure heights from the frame, and then measure heights of the 8L90 in the new frame. Hopefully we can make any necessary adjustments to the floor before sitting the body down. A new floor is going in the car so we should be able to modify it on the rotisserie before paint.

[Grayel]

Is that the Year One 17" N90 rim mounted on the new frame?
Is that what you'll be running on the finished car?

[mlangkamp]

Yes, we are running the 17" N90's.

[pro86tourn]

Any issues with the brakes rubbing the lower control arm? I have the exact setup on my monte with little to no clearance (passenger side even grooved the rotor)

[mlangkamp]

Any issues with the brakes rubbing the lower control arm? I have the exact setup on my monte with little to no clearance (passenger side even grooved the rotor)

Did you put the steering stop on the lower control arm? I guess I can't say for sure yet as we don't have a drivable car yet. I will check that the next time we're working on it though.