C123 build

Hello everyone!
Thanks to a lot of help from the archives I just came off a instillation of a c153 on my little farmall C. I love the tractor! Thanks to all who contributed to those forums. Everyone was right.... It wasn't that complicated but the little details drove me nuts. I think it turned out well.
On to the topic of my post. I recently aquired another little c very reasonably and got it to run after sitting to what I could only guess a couple decades. I've already got my eye on this engine. It's quite possible to put the overbore kit in the c113 to make it 3 1/4". The c135,c146, and c153 all use an updated head with more air flow and a different manifold. I guess what I don't know us if the head bolt pattern changes as well with the redesigned head??
It seems you could gain a bit if it was possible. Has anyone tried?

im going thru my c123 right now and its 3 1/4 over bore the only problem ive had is finding the rings for the flat head pistions. i had to have them made. if you have flat head pistions ive got the part# for them. other then that, im having no problems

when i tore down the motor it was already bored to 3 1/4

I'm sure it would be usefull. Maybe I shouldn't assume but does red power make a fire crater piston that's 3.250? That's what I would gun for. If they don't I've herd the name Lemmon's out if Indiana? A set of custom pistons might be a little overkill for my project. Maybe not. I'm just brainstorming ways to beef up that little engine without a complete swap. Make it look somewhat original with a little extra to play with.

What about the kits sold here.
Won't they fit?

I'm sure they would. I guess what I'm asking could be personal "secrets " in regards to how people get a few extra horses out of that little engine. Mix matching kits for example. Taking a head off of a engine and putting it on another. The head off a c153 for example. (Will the head bolt pattern fit...manifold studs match up for a stock manifold?) Maybe an overbore kit from a much larger engine that might require a little bit of machining to make it work. I've heard of people doing some pretty amazing things with these little farmalls. My ultimate goal now that I have built my C with the c153.....is to build one with similar hp and not make it bluntly obvious that work has been done or a complete engine swap with a engine that isn't origional. If fishing looking for a hand from the old timers that thought outside the box

Over the past few years I've been rebuilding an F-12. I realize overall engine design is different than your C. The F-12 still has a C113 stock motor.
I used SC 3 1/4" overbore kit with step head pistons. I'm not familiar with what it takes using that kit in C. To fit them in the F-12 block required machine work on the sleeves and block both.
From the obvious increase in cubic inches I also spent many hours porting and polishing the head and manifold. The Heisler manifold I'm using is a huge improvement from either of the stock manifolds. If I hadn't been given new valves for free and already had new valve guides I would have liked to look into seeing about changes valve sizes. Every little bit to help it breath more.
I sent my cam off to Berry cam explained what I was planning to do with the tractor. I wanted maximum HP increase. I'm not planning to pull with the tractor. Just driving in cruises, parades, may do some plowing. He did a mild build and I'm very happy with the results.
I'm still experimenting with carbs. I've been told to open up the Venturi. I have plenty of parts carbs on the shelf.

I'm by no means an expert. This was only the second complete engine rebuild I've ever done. I've spent many hours researching books and online. It's your tractor. Your money. Decide what your goal is to do with the tractor and save up for whatever it takes to make it happen.

How much engine do you want , I guess what I mean is
your pocket is the limit . I would use the 123 kit
use 2.02 gm valves and on a all fuel head with dome
pistons , large cam ,and a late model manifold
ported and polished , but I ain't rich , just
thinking of what could be done if you can afford it.

How much engine do you want , I guess what I mean is
your pocket is the limit . I would use the 123 kit
use 2.02 gm valves and on a all fuel head with dome
pistons , large cam ,and a late model manifold
ported and polished , but I ain't rich , just
thinking of what could be done if you can afford it.

Seth..very useful information and thank you. I have spent a lot of time thinking as I've started overlooking this tractor. I agree that the head and cam is a good place to start. The more fuel and air you deliver can go miles over sheer bore diameter in my thoughts.(though that extra bore could surely help You mentioned gm valves. This is my grey area. I haven't built a motor that wasn't stock so finding sizes that work...the according guide...and seat combination and a machinist that can accomplish this...is where a lot of my curiosity lies. I would like I said want to stick with something that appears stock to really turn heads.... The crank is another good spot to look at. In my mind instead of taking a crank and stroking it, and splitting your connecting rods to match, could you take a set of rods and a crank out of a 504 gasser (c153) and install them in a c123? The wrist pin placement is something I'm concerned about in that senario. Maybe there placement in a standard 3.250 step head is tolerable or could be fixed with a little milling..?..Im sure a set of custom pistons at that point would offset the cost of stroking a crank. I do a lot of thinking out loud on here if you haven't noticed. My hope is that someone has done something similar or has an opinion on how I could go about this if it hasn't been done before. I'm not trying to be cheap. Just trying to avoid throwing money in a pit. I'm sure there are ways to cut a little cost and still build a little animal thanks in advance!

I'm sorry kub6040 mentioned valves. Credit due.

You need to bore the block at the bottom to get the 3 1/4 sleeve to fit doesent take much.

Later 135, the 146 and 153 have more head bolts then the 113, 123, and early 135.

They quoted me a price on hi-dome 3 1/4 so they must have them.

Kub6040, why an all fuel head? A distillate head or a kerosene head has lager combustion chambers (and shorter valve stems) than the gasoline head, giving a lower compression ratio.
Thanks, Hendrik

Well I think the tractor gods read my post and are giving me a sign!.......and trying to save me some cash! I just was in contact with a man that has a 340 utility with the c135. Hes paring it out and will sell the engine for a good price and he's close by. I've read and assume the instillation would be similar to my c153 I just installed, my question is is the back of the crank drilled for a pilot bushing like the 404?? My c153 was a power unit so it wasn't. Being that this motor is out of a tractor are there less headaches? I would guess the radiator and piping issues would be similar?? Just wondering if the 340 "utility" makes a difference.

I don't think the back of a C-135 block out of a 340 will bolt up to the C bell housing.