AC 301 or Cummins??

Just curious to know what you guys would build if building an orange tractor for a light pro stock class? We can build component chassis', so would you build a 301, hogged out to about 360, or would you go with a 5.9 Cummins. Our cube limit is currently 401 for alky and diesel, but I could see that changing to only 370 for the alcohols. Thanks for the thoughts....

Mmmm i luv them 301,s, Cummins have alot more parts readily avaliable but id try to make an AC work! Wonder how much reliable horse power you could get out of each

Edited by DougG - 14 Aug 2013 at 7:18pm

My opinion is an Allis needs an Allis motor. 

I would likely run alcohol. We are not limited to turbo size, but can only run one. I guess I was wondering more about air flow capacity of either head. We have to run the original cast head. Thanks!

I have to agree with bob c. Most of the pulls around here require block and head to be made my same manufacture of the tractor. But if there were more pulls that allowed it my 190 would have a cummins. 20 years newer technology, tougher everything, and way better parts availability.

Same with us cummins is the legal replacement for the AC motor

That is correct. In the diesel category The 301 Allis will do anything the Cummins will do.... But it will cost more for sure. I thought the original post was for a diesel application.

Going alky would make the cost between a Cummins and the Allis 301 closer together I would think. You would have to buy a ignition system, turbo, fuel system, pistons, conn rods,(I assume they use aluminum rods in an alky Cummins) That would all be the same cost between the two engines. You would have to bore the block in a 301, but you would have to convert the head on a Cummins to spark plugs. I would guess the cost for each of those would be similar - offset.

Edited by O.P.S. Heads - 15 Aug 2013 at 9:36am

Thanks guys.... I have been looking for a cng or lp Cummins head..

Thanks, Bob C. IL.   What club do you run with??

The major hurdle with the 301 is going to be the cylinder head.  Think about it for a minute.  It's 6 cyl with a siamesed exhaust port.  When the exhaust valve opens the cylinder is under pressure, this creates a sonic wave, the reason an engine is verry loud without the exhaust manifold on. WIth the fireing order of a 6 cyl and the siamesed exhaust port there is some overlap of exhaust events twards the tail end of one cylinder and the start of the other cylinder shareing the port. Also when that cylinder is closeing and the other cylinder is opening, generateing that sonic wave, the closing cylinder is on overlap, or the intake cycle is starting. This sonic wave is going to cause problems which escilate with RPM 

Edited by wi50 - 15 Aug 2013 at 2:04pm

Do 426 heads suck as bad as the 301?

I'm going to side track this thread, but as long as we are on the subject of heads I'd like to share a project that I've been on for a while that I now feel comfortable with.  Hopefully a few of you will find it interesting.

Edited by wi50 - 22 Aug 2013 at 8:36pm

Lovin' that new MM chamber!

You guys know about this stuff and I don't so that's why I am asking the question: With the 226 engine having no combustion chamber in the head and the performance being pretty good compared to the Farmall's and others with combustion chambers, is a well shaped combustion chamber in a head (like the photos of the prototype) better than a head with no combustion chamber at all for an application like this? I assume it is since your new heads are not flat, but how come?

Maybe the question I am asking is if someone was to make a head for a spark plug Allis Chalmers, would a better performing head have a combustion chamber or not?

Thanks for the info and photos. Even has a water jacket. Not easy to do.

Edited by O.P.S. Heads - 22 Aug 2013 at 9:57pm

Make sense. Thanks for the explanation in a format I could understand.