alex722607

iTrader: (4)

So i have a 1988 Pontiac Trans Am that is getting the LSx treatment.

I recently acquired a 2003 LM7 chevy 5.3 engine with roughly 120,000 miles on it. My plan is to put an LS1 intake on it coupled with F-body specific accessories and oil pan and mounts and join it with a 4L60E transmission. So I need to ask, being that this is a budget swap, what else should I change?

I want to have decent fuel mileage meaning around 24, while at the same time having just as much if not more get up and go than by gen 1 chevy sbc. I know that some of this can be achieved with tuning, but before this engine goes in the car, I would like to know if anyone could give me recommendations.

Another question, does the flexplate have to be changed?

alex722607

iTrader: (4)

anyone?

76larkman

flexplate should be ok with the 1 you have.motor mounts I would get the speedway version cause it should make motor sit directly on sbc mounts. I didnt use them I got plates off ebay, I ended up shimming motor up/drilling new mount holes on frame. Holley oil pan set up should do you well(another I wish I used). Im in the process of changing my 76 skylark over rite now. things you learn as you go I guess. your car accesory idea probably best as for hood clearance. I probably go stock for now if you want mpg out of it, should have better power than sbc did anyway.

Noremac

Considering that a silverado gets 16-20mpg's at 5500-6000lbs, I dont see why 22-24mpgs would be hard to do for a 4000lb car.

If memory serves, an early 6.0 flywheel will adapt to the transmission you have.

76larkman

I know turbo 350/400 tranny torque convertor bolt pattern is different than the 4L60E has. your 5.3 probably already had a 4L60E on it so im assume you be ready to go on flexplate. I do know 1 bolt hole from tranny to motor on top right side there no hole in block for as thats what I found on my 5.3.

alex722607

iTrader: (4)

thanks guys.

As for mounting it, I purchased a notched K-member for use for A/C mounting and it came with adapter plates for use with ls1 clamshells. The engine was burning oil which is what I recently discovered after pulling the heads and seeing carbon- and a hell of a lot of it. So I need new heads, and new gaskets and I might as well get new bolts while I am at it. (It comes in a kit)

Should I be changing the camshaft? Or can I just bolt on what I need to bolt on and plop it in and be all set?

76larkman

cam depends on what you want for power out of it. I been trying to figure out cam thing as well. Im going to wait until mine is going see what its like first. Save money now for other stuff like getting fuel system on path needed. I think in your situation cam install in car probably little tougher in that engine compartment.

MrSlinger85

iTrader: (3)

I'm doing an LY6 in a 94 F-Body. I'm probably $4k into the build, but I've also bought most of the stuff new. I think I still have another $2-3k left on parts since I am having the LS3 heads ported/milled. The problem I've noticed is using a non F-body motor means sourcing all the f-body crap...which adds up quick.

alex722607

iTrader: (4)

You can say that again. The pan will run $200+, accessory brackets and accessories themseleves are around $800, gas tank and related stuff $300, new heads and related seals/gaskets around 5-600 bucks. It adds up very quick.