What can I do for performance on a SD-220 inline six?

So before I decide to rip out the original motor on my truck for something else, I thought I would see if I can get any ideas for the orginal.

The truck is a 1950 International L-112, with the original SD-220 inline six--rated at 90HP & 173 ft-lbs @ 3600 RPM (redline). The truck is going to be a (moderately) daily driver for a while, and needs to be able to go on the highway regularly.

I had a 85HP 4 cylinder Mazda 2WD pickup for a while, and it wasn't much for driving on these highways around town. When I moved here, it seemed like it didn't take long for the motor to go downhill fast from over-winding the hamsters.

I've heard there may be a turbo kit for tractors in the works using an updraft carb for these motors, but don't know what kind of power it adds.

I'd really like to do 20 MPG and good driveability, but don't know if that is possible. Some guys suggest a slight increase by going to the slant-valve SD-240, which is apparently also less prone to dropping valves. The motor apparently has a forged crank and cam shaft, so I guess that's a bonus.

This motor is probably in pretty bad shape. It's been sitting for about 40 years, 10 of which the motor was fairly exposes and the manifolds were loose. It also apparently had a bad rod knock when parked. I think we checked years ago, and couldn't get it to turn over.

 

I have a BD240 in my '56 S110 and the only real performance part I've found is an Edelbrock 2x1 intake for it (Nicson made one too). Eventually I'm gonna look for a cam blank and see about a slightly better grind, and make a set of headers for it. As far as MPG goes, your best bet would be a rearend swap methinks.

I'm a little biased toward the IH engines...bulletproof is a good way to describe them. They don't make huge horsepower, but if it's not a hotrod then speed and MPG can be made up in other ways. It's A LOT of work to put something else in and the old argument 'well parts for xx engine are rare and hard to find' is bullshit when it comes to IHs.

 

I am thinking about going to an Explorer rear end, as I understand it uses the same wheel bolt pattern and is the exact width of the stocker. I think I'm going to start off with the original wheels, as they seem to be in good shape (tires hold air still, anyway).

Do you have any good sources for rebuild parts? I've got the parts interchange from Old IHC, but that's not really focused on strictly engine. I did see a YouTube video where someone put a GM TBI setup on one and it worked fine LOL. I don't necessarily think I need FI for good fuel mileage, though.

Are there any 5-speeds that bolt up? I have the 4-speed floor shift, but I think first gear is 6 or 7:1, and 4th is 1:1. It would be nice to have overdrive.

I'm not necessarily looking for speed, just comfortable driving around here.

 

If the engine is bad you should consider an engine swap. Pickup trucks have lots of room.

It depends how you want to use it but if you are not going on the interstate you may not need to change the rear axle. I put a 360 and automatic into an old Dodge pickup that came with a slant six and 3 speed manual, did not change the rear axle, and was happy about the whole thing. It had plenty of oomph at low speeds and was not as buzzy as the slant at hiway speeds because of the shorter stroke motor.

If mileage is an issue you might consider a Dodge 318, or Ford 302, both good mileage motors. The Chev 305 not quite as good. Of course if you use an automatic overdrive trans, that overcomes the low rear axle gear.

 

There is a 4spd w/ overdrive IH tranny that will work but you have to make an adapter. Otherwise 1:1 final ratio is as good as it gets. The Exploder rear is a common swap and the ratios can work out to a much more favorable cruising speed and RPM. All of which will have a positive impact on MPG.

I'll never understand why an engine swap is preferable to a much, much simpler rearend swap--especially in IHs. Those trucks are designed for tall, narrow I6s and you will run into serious issues clearing the steering box if you try and stuff a V8 in.

As far as rebuild parts go, I don't really know as far as the SDs go. For my BD I generally just head to Napa. I'm a little spoiled as I live in Montana, but they're not as rare as you might think

 

Over at www.oldihc.org there's a guy named Kevin who has either a BD or an SD six with a Keystone turbo kit on it. Keyston worked with him, and it uses his original downdraft Holley [with a few modifications].

Here's a link to pics on the Keystone website with photos: http://www.keystoneturbollc.com/id80.html

 

I live on the other side of the river from Portland, OR. Highway is the only way to get to Portland, and pretty much around Portland efficiently (unless it's rush hour).

I still have to get the truck shipped half way across the country before I can really start working on it, and I have a very small space to work on it. I just don't know what shape the insides of the motor are in, and if I did a swap, I could have the drive train built and ready before the truck got here (using the space the truck would occupy)--so that's one thing I am considering.

Cool, thanks for the link! V8 power from the I6, that's good for me. These trucks have all forged internals and 6.5:1 compression ratios--might be good for a lot of boost.

It looks like there are a couple 5-speed OD's of the era, but they look like probably heavy truck transmissions, which wouldn't work. I also need to find *which* 4-speed my truck has--it looks like there is one synchromesh, and one not--which would probably suck to drive.

I've seen a pretty clean V8 swap on OldIHC. A member has a really nice one that he originally had the I6, but swapped in a SBC with a Heidt's IFS. The SBC fit inside the inner fenders without cutting, and re-routing the steering column didn't *look* bad. It'd also get rid of the impaley-prone long steering column LOL . I plan on keeping the straight axle and steering though.

I definitely would like to keep the original motor, it just needs to be fairly reliable and drivable. I have a '41 Chevy waiting in the wings later too that will be the weekend fair weather cruiser (someday).

I've been trying to Google the gears in the Explorer rear end, and most of what I'm finding is 3.73's & 4.10's--which doesn't get me anywhere. If my calculations are correct, at 60MPH a 2.88 would be about 2000 RPM (original trans), and a 3.03 at 2100. The 4.10's would be about 2600 I think (a little less for the 3.73's, if it has those).

I'll have to go try out a NAPA. I hear Rock Auto carries some stuff, too. I've struck out on a few other auto parts and brake & clutch places.