lt1 and 4l60e gearing questions

[lt1shortbox]

Just getting going on my project 1972 k10 shortbox. I have installed a 1994 lt1 and 4l60e mated to original np205. I am planning on running 33" tires and I was hoping for gear ratio advice. I am wanting the truck to be a very nice driver and will be mostly a pavement pounder. Any assistance would be appreciated. Any one else that has done this swap I would love any advice-pitfalls to look for.

[Bigdav160]

What does it have in it now? 3.08?

You won't be happy with that. Minimum would be a 3.42:1

I'm going for a similar setup in my Suburban but went from a 4.10 to a 3.73:1

[MARKDTN]

3.42 is a great all-around ratio

[lt1shortbox]

Will 3.42 be low enough to utilize the overdrive well?

[MARKDTN]

No. My '83 K20 is stock with 700R4 and 3.42.

[lt1shortbox]

Yes truck has 3.08 now. I was guessing 3.73 or 4.10 but was hoping for some solid info from the forum.

[1968k10blue]

I have the 4.10 and without overdrive it sucks! Even with 31 inch tire I'm running 3000 RPMs at 65 mph!

[hugger6933]

My first impulse was 3:42 but with the 33 inch tall tire I might lean more towards the 3:73. Jim

[lt1shortbox]

Does anyone happen to know the rpm range that is best for cruising and economy with this engine? It is from a 1994 z28 camaro.

[Tinkermc]

lt1shortbox I don't want to get you or me in trouble but if you want to move the 308 PM me please.

[hugger6933]

Normally I say go with the 3:42's in most cases. But the tire are playing a big part in this formula as well because the taller the tire the more gear you really need to get the same truck moving. For example, [Now don't jump on me you tech guys this is example only and not close to accurate]. If you have a truck with say 28 inch tires and 3:42 gears that came from the general this way and everyone is happy even the truck. Now you go to the tire store and a super deal finds you putting 33 inch rubber on this same truck, you take off down the road truck runs fine but you just think it doesn't feel as strong as it did before, what could those tire guys have done to my truck just putting on tires? Well, they just put on the tires but being taller you EFFECTIVE gear ratio now FEELS like your truck has a 3:08 in it. Not a huge diff [sorry for the pun] but one none the less. This is why I am saying the ratio should be at least a 3:73 or maybe even a 4:10 with this tall of tire and then you can rest assured that you won't have gear wander where the trans is searching for drive or OD and back and forth[we have all been in something doing that. Jim

[mmiddle]

The LT-1 is a great motor. I love mine in the 87 IROC. The car has 2:73 gears (common for IROC's) The car will spin the tire through all 4 gears with no problem. But in a truck, especially a 4x4 with 33" tires 3:56 or 3:73 are the way to go. I also have a 96 LT-1 I will be putting in my boat this spring.

Send the computer out and have the VATS and emissions tuned out. Then get the factory service manual for the 94 Camaro and take your time. Do not "butt-splice" the wires, solder them with heat shrink.

Also Consider replacing the water pump and Opto-spark NOW! Also, the steam line from the back of the heads must be routed to the return side of the radiator. (learning the hard way)

[lt1shortbox]

Thanks for the info, I have a painless wiring harness that i believe takes care of the vats but I guess I will find out soon. As for the steam line, I am using the complete cooling system out of the camaro into the truck, will I still have something to deal with?

[MARKDTN]

Originally Posted by mmiddle

.... Also Consider replacing the water pump and Opto-spark NOW! Also, the steam line from the back of the heads must be routed to the return side of the radiator. (learning the hard way)

This is very good advice. In fact, you may want to look at converting to '95 up style Opti. If you Google around you will find info on doing it and why. The later version is much more reliable and not as suceptible to water. At least replace it and the water pump while it is out. Use Delco or top quality parts. The Opti is the Achiles heel of the LT1, but if you know about it, you can take steps to keep it in good shape.

[hugger6933]

I had one in a 95 SS Impala. the torque is flat as a table top it pulls hard the same from about 1400rpm to 4 something I never stayed in it that long by that time it was wound that far I was going way faster than Johnny law would let me. I would also think that the weight of the old whale tail body style and the body style truck we are talking here should be close give or take a couple of hundred pounds. If I remember the car was just short of 4600 or 4800 lbs. If you have ever had one you know the trunk is bigger than some apartments. I think it is a great choice for your truck, and this post has reminded me I have a LT1 under a cover in the corner of my shop I had bought a roadmaster years ago to get the drivetrain out of. Good luck with your project. Jim