Monte Carlo LT1 Build

[kevm14]

Sounds like 0.550" is about the limit (http://www.impalassforum.com/vBulletin/ ... p?t=375961). Also, you may need to consider screw in rocker studs at the 0.550" range. None of the cams I recommended exceed this. It also makes sense because there is no point to more valve lift on stock LT1 heads anyway.

There are apparently low profile seals and valve retainers that you can use to help. Definitely don't want to be breaking valve springs. That would be bad.

[kevm14]

Thoughts on headwork being driven from your cam choice:
Option 1
Select a cam that will work within the valve lift limits of the stock heads, and that won't pull the pressed in rocker studs. Less power but less work required.

Option 2
A more aggressive cam selection (not sure on exact lift but somewhere in the 0.525" or 0.550"+ range) will require the valve boss to be ground down, and while that is happening, you would upgrade to threaded rocker studs.

Option 3
Run aluminum LT1 heads, which get screwed in studs from the factory. Not sure what lift they are capable of without machining. Iron heads flow well and I would not consider the upgrade from that standpoint. I would discount this option but I wanted to list it anyway.

[Fast_Ed]

More thoughts on the cam: about as far as you can go on the stock heads (airflow reasons) may match up well to your drivability, emissions and fuel economy goals.

There are fuel economy goals?!

Also, for those interested in the dimensions of either the B-Body engine bay or the LT1, they are separated and on display in my garage for a limited time only!

I'm definitely looking forward to getting that exhaust onto the Roadmaster. Should sound nice. But that's another thread in itself.

[kevm14]

There are fuel economy goals?!

There aren't? Should be capable of over 20 highway with the cams we've been talking about.

[Adam]

There are fuel economy goals?!

There aren't? Should be capable of over 20 highway with the cams we've been talking about.

It used to get 15-18 combined. Or single digits when being driven hard. The Monte Carlo, that is. Highway was in the low 20's maybe? My 307ci Cutlass with 2.73's got 26 mpg once, but it was very slow the rest of the time.

[kevm14]

I'd say it was still slow getting 26 mpg.

[Attempt to work in Mitch Hedberg "used to, too" joke failed]

[Adam]

Another (less exciting) option would be to leave the drivetrain completely stock (header/manifold choice not withstanding) and use that time to dial in the rest of the car. The engine ran reasonably well immediately before we removed it, so it should run just as good when it goes in the new car.

The rest of the planned changes are not trivial:
- B-body front spindles and brakes
- Fuel injection (tank/pump/harness/lines, etc...)
- Limited slip upgrade
- A/C re-engineering and integration with the G-body controls (I want A/C to work)
- LT1 driving the factory gauges
- 4L60E fitment w/driveshaft and trans mount
- Rehabbing the rest of the car, which has been sitting for 12+ years

While this is less exciting than also dropping a 350hp (+, not unreasonable) engine in place, it will eliminate what could potentially be many unknowns from the swap.

Some things that would be needed for future output increases that need to be addressed anyway could be done, like the fuel pump upgrade.

One added bonus to a stock LT1 install is we would get to experience (for a time) what a G-body could have been like in '94-'96 if GM had continued the platform for another generation like they did for the B platform.

[kevm14]

You also need to determine a safe operating RPM range. Word on the street was 6,500 is as high as you want to go on the stock opti rotor. You may also back it down a tad from there due to stock rod bolts. So if you want to shift at 6,200-6,300 rpm, choose cam appropriately. Unless you want to do ARP rod bolts. If you already have to replace the oil pan...

Oh, leave the stock oil pump or replace with stock if you do not trust it.

Stock timing set may be fine.

[kevm14]

Another (less exciting) option would be to leave the drivetrain completely stock (header/manifold choice not withstanding) and use that time to dial in the rest of the car. The engine ran reasonably well immediately before we removed it, so it should run just as good when it goes in the new car.

The rest of the planned changes are not trivial:
- B-body front spindles and brakes
- Fuel injection (tank/pump/harness/lines, etc...)
- Limited slip upgrade
- A/C re-engineering and integration with the G-body controls (I want A/C to work)
- LT1 driving the factory gauges
- 4L60E fitment w/driveshaft and trans mount
- Rehabbing the rest of the car, which has been sitting for 12+ years

I actually don't disagree at all. I'd probably cross some stuff off your list unless you know it was failing. Then, later on, you can just suck it up, pull the engine, and do whatever you want to do with it out of the car, which will probably be easier overall.

There is PLENTY to do before you try hot rodding the LT1. No harm in planning, though (unless it takes away from doing).

I'd probably recommend some light tuning since it will need tuning anyway to correct for the gears and tire diameter.

[Adam]

You also need to determine a safe operating RPM range. Word on the street was 6,500 is as high as you want to go on the stock opti rotor. You may also back it down a tad from there due to stock rod bolts. So if you want to shift at 6,200-6,300 rpm, choose cam appropriately. Unless you want to do ARP rod bolts. If you already have to replace the oil pan...

Oh, leave the stock oil pump or replace with stock if you do not trust it.

Stock timing set may be fine.

I think 6K-ish is a reasonable redline. That is plenty of RPM to make more power than can be put down on the street.

According to the (accurate?) 9C1 oil pressure gauge, there was plenty of oil pressure, so I'm not worried. When the cam swap happens, I will probably replace the timing set. Unless I don't feel like spending another $80.