Bore on M Farmall

[42 M]

What is the biggest bore I can safely bore my block to? Will be a dead weight puller. I'm thinking 4 1/2 or 4 9 /16. Will not be stroking the crank yet.....

 

[ih560]

(quoted from post at 19:59:37 04/16/12) What is the biggest bore I can safely bore my block to? Will be a dead weight puller. I'm thinking 4 1/2 or 4 9 /16. Will not be stroking the crank yet.....

I don't think you can take an M block that far, it is very dependent on the shape of the engine and if there is pitting on the outside of the cylinders and if the cylinder are centered in the casting. I would think with a very good M block you wouldn't want to go any bigger than 4 3/8", maybe it could be a little bigger, but I would rather err on the side of caution.

 

[emtiv1099]

You will need a super m block. I think the webbing in the bottom end is thicker. If you bore the block 4.375 and stroke the crankshaft 7.25 that will get 435 cubic inches.

 

[HMPuller]

A plain M block can only be bored to 4.25. A super M,400 or 450 block you can bore to 4.375 but you will need to do a small amount of hard blocking at the bottem of the cylinders.

 

[andrew hegeman]

my super m has a 4.625in bore. it handled 3000rpms for alot of years until it split a sleeve. we only run water in the head though.

 

[Superih]

(quoted from post at 19:36:13 04/16/12) my super m has a 4.625in bore. it handled 3000rpms for alot of years until it split a sleeve. we only run water in the head though.

Your Super M has 4.625in "sleeves", the original bore would mostly be gone.

 

[Gary Baker]

They would be all gone and then sum

 

[42 M]

So 4 1/4 on my M Gary? I bought some parts from you early this year cam and rods. Is it possible for a 4.36 bore without making it totally useless? Please email me .

 

[Gary Baker]

my email is open or call me 734-678-9688