JimZ 65 short project

[JimZ]

I've owned this truck for 30 years. It is a Custom Cab, wide window, short bed fleet-side, originally with a 283 and 4-spd on floor (someone added later). Found a bad wire under the dash one day in August 2008 and decided to rebuild the whole truck now that I was retired. This is my first project, learning on the fly. Prior to this, my expertise was oil changes and spark plugs. Here are the details so far:
The engine is a GM Generation IV LS3 6.2 liter (376ci) rated at 430 hp and 426 lb torque. It is fully computer controlled, coil on plug, 6 bolt main, fuel injected, has a drive-by-wire accelerator (not a Toyota product), and is all aluminum. Other accessories include a 1 wire alternator, permanent magnet gear reduction high-torque starter, serpentine belt drive and a 7 cylinder continuously variable a/c compressor.
The rear axle is a 12 bolt GM with Auburn posit-traction and 3.07 gear ratio. I removed the gas tank from behind the seat and installed an aluminum tank in the rear.
The transmission is a GM 4L80E 4spd automatic with a .75 overdrive. It is fully electronic and is controlled by a computer. The frame and suspension has been disassembled, blasted and powder coated. Every bolt and bushing replaced.
Front disk brakes are 12" drilled and slotted. The rims are 15" Cragar S/S, a classic 60's look. They are mounted with 275/60 R15's on the rear and 245/60 R15 on the front. Strange Engineering Chrome Moly drive shaft with Spicer 1350 series yokes and u-joints. My brake and fuel lines are an unusual tubing called "Cunifer" which is a copper/nickel; alloy tubing that can be hand formed and is virtually corrosion proof. Working on installing a Vintage Air Gen IV Magnum a/c and too many other things going on.

[p_rubottom]

Very cool! Keep up the good work

[Captainfab]

Very cool build and very nice work


That rear gear sounds a little tall for use with an OD trans. Have you calculated your cruise rpm's with your tire size?

Oh and welcome to the forum

[JimZ]

Richmond calculator says 1862 rpm at 65 mph with 3.07 rear end, .75O.D., and 27" rear tire height. Is that going to create problems for me?

[Captainfab]

I'm not an expert at figuring this, but in my mind I'm thinking somewhere around 22-2400 would be optimal. To low of a rpm isn't good for an engine, particularily a HP engine like the LS3. The lower the rpm's doesn't necessarily mean better mpg's. The engine needs to operate in it's 'sweet spot' in it's power band. I would recommend posting a thread about this in the 'Engine and Drivetrain' section of this forum. There are guys that hang out over there that would have an experienced based answer for you.

I'm not trying to pick on you, I'm just trying to help you avoid a possible issue later on.

Originally Posted by JimZ

Richmond calculator says 1862 rpm at 65 mph with 3.07 rear end, .75O.D., and 27" rear tire height. Is that going to create problems for me?

[JimZ]

I appreciate the feedback and suggestion. I'll look into this. Being a novice, I missed this as a possible issue. That's why I'm here. Thanks.

[66ChevyMax]

Any idea what happened with this build?