Author Topic: LS swap?  (Read 22475 times)

Offline 86c10

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Re: LS swap?
« Reply #15 on: April 27, 2011, 06:03:56 pm »
If I stay with the 2.73's and swap the th350 for a 700 my rpm @65 would be around 1500 with 225/75/15. Would this be a problem for the 700? I've read that they don't do well with low rpm's in OD, but  that's just something I read in another post.

Offline roadrage41

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Re: LS swap?
« Reply #16 on: April 28, 2011, 06:27:22 am »
hmm, yeah you'd be better off with a 3.xx gear. but then the cost starts coming up with a tranny swap and a gear change. find a beater s-10 for putzing around and use the big truck to haul big stuff as needed?
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Offline Edahall

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Re: LS swap?
« Reply #17 on: April 28, 2011, 07:45:40 am »
Your biggest gain right how would be to ditch that TH350.  That transmission does not have a lock up torque converter so some of that fuel is being used to create heat.  If you stay with the 2.73 gears, your best bet would be going to a SM465 4 speed manual.  They're cheap, tough and reliable.  With 2.73 gears and a 305 engine, you don't have enough low rpm torque to support an overdrive transmission.
1990 ¾ ton 4x4 Chevy Suburban
-Cummins Diesel - 12 valve - factory rebuilt
-6 speed bullet proof manual transmission - NV5600
-Gear Vendors Overdrive
-Upgraded Holset HX-35 turbo
-NP205 iron transfer case
-3.73 gears
-2" Lift

Offline 86c10

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Re: LS swap?
« Reply #18 on: April 28, 2011, 09:34:48 am »
hmm, yeah you'd be better off with a 3.xx gear. but then the cost starts coming up with a tranny swap and a gear change. find a beater s-10 for putzing around and use the big truck to haul big stuff as needed?
That's what I do now, use the 99' prizim for my DD and use the truck when I need to. It's worked for the last 5 years, so another year or two won't hurt.

Your biggest gain right how would be to ditch that TH350.  That transmission does not have a lock up torque converter so some of that fuel is being used to create heat.  If you stay with the 2.73 gears, your best bet would be going to a SM465 4 speed manual.  They're cheap, tough and reliable.  With 2.73 gears and a 305 engine, you don't have enough low rpm torque to support an overdrive transmission.
I've thought about that just for the fact of not wanting to spend much on a rebuild if the th350 dies at some point. I would rather change a clutch than have the th350 rebuilt. How much of a pain is it to convert an auto to a manual? I know I would need the pedals and slave cylinder out of the donor truck. In the end would it just be easier to buy a 4 speed truck and sell the auto truck? I've only got about $900 in the truck, it's not in bad shape but I don't want to dump a lot of money into it.

Offline Edahall

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Re: LS swap?
« Reply #19 on: April 28, 2011, 11:15:51 am »


Your biggest gain right how would be to ditch that TH350.  That transmission does not have a lock up torque converter so some of that fuel is being used to create heat.  If you stay with the 2.73 gears, your best bet would be going to a SM465 4 speed manual.  They're cheap, tough and reliable.  With 2.73 gears and a 305 engine, you don't have enough low rpm torque to support an overdrive transmission.
I've thought about that just for the fact of not wanting to spend much on a rebuild if the th350 dies at some point. I would rather change a clutch than have the th350 rebuilt. How much of a pain is it to convert an auto to a manual? I know I would need the pedals and slave cylinder out of the donor truck. In the end would it just be easier to buy a 4 speed truck and sell the auto truck? I've only got about $900 in the truck, it's not in bad shape but I don't want to dump a lot of money into it.

It's not too bad converting from an auto to manual.  That's what I did on my 1990 Suburban.  It used to have a TH400 and I converted it over to a NV5600 6 speed manual.  You'll also need to cut a hole in the floor for the shifter.  And you'll also need a shorter drive line from the donor truck or get yours shortened.

Yes it would be easier to buy a 4 speed truck if you can find one and sell yours.  But if you do, keep the 2.73 axles.  Those axles make good fuel economy with a non overdrive transmission.
1990 ¾ ton 4x4 Chevy Suburban
-Cummins Diesel - 12 valve - factory rebuilt
-6 speed bullet proof manual transmission - NV5600
-Gear Vendors Overdrive
-Upgraded Holset HX-35 turbo
-NP205 iron transfer case
-3.73 gears
-2" Lift