The Stovebolt Site Forums The Shop Area The HiPo Shop 5.3/6.0 into TF with SM420?

I work on these things daily and frequently see them close to 100K, no leaks and plenty of power. Does anybody know what it takes to swap one into a TF truck and hook up to a standard truck trans? I'm thinking it may be time to upgrade if I run across the right deal.

Devin

Get the book "How to swap a GM LS engine into almost anything". Its a great source of info. I'm swapping a 2002 Silverado motor into my 57 Burb. I had an interference problem with the low mounted AC and the stock exhaust manifolds wont work because they hit the frame. The actual bolt in and fit was the easy part. Oh yeah I'm running a TCI MII front. As far as the standard trans without getting into the bolt patterns, the computer can be programmed to use without the factory trans. I'm using the factory 4L60E. Other things you will have to figure is fuel delivery(58psi). Harness and computer work, exhaust, steering, which oil pan to use, etc...
There are two other guys on here one is done and the other is like me... in progress. Maybe they will chime in.

I suppose what I am more after information wise is getting it to bolt into an otherwise stock truck. I'd rather not have to convert over to side mounts. I don't know if a traditional trans will bolt up to the bellhousing flange, whether it has a pilot shaft hole, and if there are bolt holes in the front that could be used to mount it to the frame.

I can deal with the electonics easy enough, either a modified factory computer or Megasquirt will work.

Devin

Traditional trans will bolt to LS with the exception of one bolt and you also have to get a special spacer for the pilot bearing. See the book the previous poster refered to, it has good info.

You will have to convert to side mounts, as far as I know. There is no reason to regret that as there are LS conversion mounts to go to normal small block Chevy mounts. I would assume if there are front mount holes in the engine to go with the stock mounts the fabrication would be just as if not more problematic as the side mounts.

I don't know what trouble there is with the AC compressor and stock manifolds. I have the motor and trans and the truck frame but have not started to put the two together.

I do think the LS is a good choice given the cost of small block crate motors and what an LS will put out with out complaining.

One more thing, try www.ls1tech.com for plenty of info on LS swaps.

The SM420 trans will work fine with the LS engine. I've got my original SM420 behind a standard Chevy 350, and that is probably an easier swap. Just curious, why do you want the LS engine instead of a regular small block Chevy swap? And why do you want to use the SM420 on it instead of, say, the stock double-overdrive 6-speed manual transmission that mated to LS1 engines in the late 4th gen F-bodies? Although the SM420 is a nice tough transmission, it is extremely gear limited.

I have 3 purposes in contemplating this swap. 1) Torque. My truck earns its keep hauling stuff and towing. I'd drop in a 454 or 496 if I didn't have to move the steering box to do it. 2) Fuel Economy. I get about 20 MPG out of my 235. I expect to be able to do that with an LS easily enough. 3) Driveability. If I'm going to go away from the original 235 to a modern engine the LS series is a vast improvement over 350s etc.

Why do I want to keep my SM420? I want a truck transmission for the low gears in it. Ideally I would be able to get either a Gear Vendors or Ranger gear splitter/overdrive in addition. I could add those at any time however.

Devin

why not get a late model 5-speed or 6-speed truck transmission. Plenty out there bolted in trucks, look at the 2500's. Granted in . you may even get one from behind a 5.3 or 6.0 and get the complete driveline. 5-speed is option MW3, 6-speed is option ML6

Just got to look at 2006 or earlier as the 2007 and later have the manual trans dropped.

I got a good look at a 6.0 in a friend's shop the other day. They do have a single bolt hole in the front on each side. It's been a while since I've seen a set of V8 mounts, but if I remember correctly they only have 1 hole, the lower of the 2 factory holes on each block. I bet I could make one work pretty clean with a set of stock V8 mounts, may have to fab the top piece, but that's easy.

Devin

Hi Hot Rod Dad.

Maddog Moody here. Quick question for you. I have a 59 Burb coming together. I have a nice freshly rebuilt 350 (383 stroker) I'm installing. I still have the SM420 tranny. You seem to be happy running that configuration. I'm going to be pulling a 19 ft Winnebago travel trailer. Do you think my stroker and SM420 combo will do me good?? The rear end is stock 390:1 Thanks for any input!

Maddog

If one is hauling loads, sometimes the 3 synchro(top gears) in a 420, 435 or 465, etc, are a little awkward(far apart). NP-540 series 5 speed trans' work a lot better to solve this by having 4 closer ratio gears(besides the granny gear). They come in GM, Ford, IHC, Dodge, etc., bolt patterns.

They also come with long input shafts for 14" clutches, stock bell housings won't work with these, unless one can find a stock GM adapter plate, about .25" thick, and associated bellhousing(come on SBC in big trucks.)

Look for Al top cover, 4 shift rails-look just like a 435 with one more shift rail.

Ed