farmall H motor build

mcrow4117 · Jun 28, 2020

i have a 51 farmall H that i have got to do a motor rebuild on and was thinking about buiding it so i can pull farm stock with it and be somewhat competitive. Was thinking about changing to a 300 or 350 head, lp manifold and a carb from a 300 or 350 also what size pistons should i go to to make it somewhat competitive thanks in advance for the info

jon aller · Jun 29, 2020

To in stall the factory 350 sleeves and pistons, you will need to bore the block. That would get you to 175 cid and if you tune it right, ~50hp. It would do well in 3500 to 4500 classes.
You will be short on power beyond that weight, unless you have a picker low. My first H was that setup. I would spend the money on rebuilding the governor and distributor, and work with a
shop that does race cars to do some head/valve work. You are not looking to go much bigger on the valves, but rather smoothing and removing obvious flow restrictions. I had to run a
distillate manifold and the small H carb. Those items can be reworked to easily feed your 175 cid. If you are capable welder, you can modify your rocker arms to a higher ratio by cutting 1/2
way through the short side on the bottom and pinching the cut shut and welding it.

Good luck and have fun!

jd man wis · Jul 2, 2020

There use to be a kit that you could get
from some were that had pistons and
sleeves and high dome pistons.I would
check for one of them kits I think they
use to be from farm sulply. Then the next
thing is the cam to get done. The cam
need to be replace for it to give you
more power aND it will run nice. Do as
much head work on it that you can with
porting and bigger valves if I remember
right there's not much you can do to them
heads but if you can find one for a lp
tractor them are alot better.

farmall H motor build

mcrow4117

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jon aller

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jd man wis

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