Allis 301 mods for pickup truck

First thing I would do is get a SAE bell housing, go with a Allison OD auto,they'll prolly be a 6 speed...or you could use a Eaton fuller OD trans..then figure out what rear gears that will cruise at 70-80mph interstate speeds...

3000 rpm?? I thought most were rated at 23-2500...

https://www.farmshow.com/a_article.php?aid=16410

Automatic transmission will perform better because when you shift with a stick you lose boost and have to rebuild that same boost over and over. Automatic will keep the engine boosted up all the time. I believe your choice of a 301 for engine size is much too small for what you expect the performance to be. I drove a company truck with a 3126 Cat engine that was rated at 230 HP @ 2500 RPM with 660 ft lbs of torque at 1400 RPM's. It was more than adequate for a truck that weighed 25,000 lbs day after day and regularly got 10 MPG.  I think even a 426 T&I with 7080 ratings is only 210 HP with 400/450 ft lbs of torque and a 301 is waaaay less than that.

Honestly, a DT466 out of a bus or truck would be way easier, and get you what you want. I get the Allis connection, but unless you have cubic dollars, and a lot of fabricating skills, it will be a challenge. Good luck.

my frends dad had a intercooleled turbo charged 301 in a 74 lincoln continental it had  an allisiion trans that was back in the early 80s the car was a gold  color and most of the turbo stuck out of the hood the fab work was excelant thats about all i can remember

I think it is a neat promotional idea for your business I say go for it. I would think with the right gearing overdrive  transmission you could get a 75 to 80 cruising speed at 2000 rpm. Might not be the puller you are hoping for but still be a good parts chaser.  

Edited by DanWi - 26 Feb 2020 at 9:50pm

Tom Silver did this many years ago - miserable until he put a second trans in back wards ! this was a way to pull what he wanted - keep in mind you will only have 80 hp until you get to 1800 RPM. Loaded it was constant shifting.  Docs idea of the auto is the way to go. You have a way to go - vacuum pump, motor mounts - I would use a light flywheel with a torque converter or some a clutch with the auto - don't like that idea to much involved. Using an auto automatic you have to have a kit to do this - it can get complicated pulling a load. A cable shifted automatic would be the best with a low stall TC..  IF you follow through with this an air to air intercooler would be nice .  As to RPM's a constant speed over 2500 scares me... that is throwing a lot of weight around for a long time.  Pulling at high rpm is for short time - a few seconds - long runs are a different horse..   IF you want to live on the edge - don't flog the fuel pump - keep it livable - look at some of the diesel hot rod series - nitrous and propane for short bursts - limit it to a theoretical  200 hp  for a few seconds for your fun.  How much can you add? Just keep adding fuel til you leave metal chunks on the road then back off a bit :-) Just food for thought.  

Put a Cummins in it.  Either way, weight on front axel will need to be addressed.               MACK

ac fleet wrote: The ONLY thing after all this mess is cobbled together is the failure of the end product, BUT it's your money and time so go for it! --- That baby engine will not do what you think it will! --- sorry!

this reminds me of the story about the F4 Phantom when it first came out..... Story was ..." This is the military's proof to the world that given enough $$ and HP even a BRICK can fly "..

Heyfound your posts. Hope the project is coming along well. I have a similar one. Oh and the critism never ends does it. Just go with the Cummins, its so much easier...blah blah blah. I get it though. So anyways, let me tell you about my project so far. I have been away from it for a while. But Im slowly working on it.

Allis chalmers 301
Ported head
Tuned fuel pump 198cc
Allison 1000 transmission
2007.5 GMC 3500

The engine is completely apart and has been cleaned. I gave it a acid bath. I was very impressed with how it cleaned up. I painted the block and head red. I know honestly I could only get my hands on red. It looks sharp.

New injectors to match the pump flow. Im ggoing to build a new manifold and working with a shop to put twin turbos on. This will allow me to capture a powerband down low and up top. I ported the head. And its at a shop currently getting new valve seats and planed. The machist ordered aftermarket valve springs. The stock springs were somewhere around 40lbs closed and 80lbs open. Given that its going to have 35psi boost. I needed something closer to 100 lbs closed and 200lbs opened. Anxious to see what he ordered. Its a project I want to focus on, but its gona take some time. Lets get to the allis transmission. Obviously its the transmission that came with the truck. And the transfer case. The transmission is an excellent one. Going to beef it up a little bit. Since it has plenty of miles on it anyways. Lockup converter and its currently a 5 speed. Its possible to go from 5 to 6 on these. I plan to go to the 6. This is exciting and definitely love making progress when I can. Critics will harass us to no end and it makes the end all that more valuable. Trust me digging into this just doeshave the suuport on literature and aftermarket that cummins does. And yeah if we were to take a 5.9 and tune it up we could and get alot more potential out of it. A P7100 on a 5.9 has somewhere around 800cc fuel delivery capability. But thats insane. This DB is tuned to 198cc. Im not really sure off the top of my head what a stock one is for a 7020 tractor. But its significantly more cc. Every part is pretty expensive. The cooling for this bad boy is gona be something. Gona put a intercooler and large oil cooler. Anyways your idea of what I have heard is solid.

Recent quarterly 2026 diesel pickup truck sales are:  Ford 89,540 units.....Chevy/GMC combined were 50,080.....Ram was 25,716.  Cummins engines have always helped sell Dodge/Ram trucks for sure, but are a long way behind Ford.

Ive got a 88 gmc ton 4 door ton truck with 454 and the rear end is 4.56. It came with a 400 automatic which is direct drive. It was turning 3000 going 55 mph. I put a 4L80E in it. Now its about 2200 at 55 and about 2500 at 65. It works great in that truck. Assuming 24 or 2500 rpm for a 301 for longevity id say 3.73 or 4.10 rear axle ratio it would work out but it stiil would have to have a overdrive transmission

I guess I've never heard of a Ford or Duramax making a habit of failing connecting rods. So, they must be heavy enough ??  Gayle Banks has about 14 u-tube videos of all the things he did to a new DuraMax engine to increase the HP. The last episode I saw he had just broken into 1,000+ HP on the Dyno and the cylinder heads, pistons, crankshaft and connecting rods were STOCK.

Edited by DrAllis - 12 Jul 2026 at 5:18pm