engine size

Straight M is 3-7/8" bore piston, 5-1/4" stroke, 248 cid. Super M, SM-TA & 400 are 4" bore, same 5-1/4" stroke, 264 cid. The cast cylinder walls the dry liners or sleeves go into are larger ID AND OD. The 450 had 4-1/8" bore, same 5-1/4" stroke, 281 cid, still larger bore for the sleeve to fit into and an even larger diameter on the cast cylinder OD.

IH, M&W, TSC, and others made kits with thin wall sleeves to enlarge the cyl. bore and displacement, typical for a straight M was 4.00" bore, 264 cid. Several guys here claim to have bored M's and Super M's out to use 4-1/8" sleeves. This contradicts what IH and M&W published back in the 1960's, that high compression 4.00" bore was as big as they offered back then. I guess if you want that last 17 cid bad enough to risk your entire block Go For IT.
 
With sleeve out of block a original M block was around 4.125 ID. 264 and 281 blocks are around 4.25 ID. Both a 264 and 281 will use 4-1/8 piston and sleeve or a 4 inch piston and sleeve without machine work. M block will only go to 4 inch with sleeves without machine work.
 
my 400 has a 248 m replacement block in it bored out to 281. machine shop ruined my 264 original block and bored out a 248 to replace it with. that was in 1981 and it's still running good.
 
My Super M has thin wall sleeves and 4 1/8" (oversize) pistons. No boring was required. just 'dropped' em in.
 
I bought my first M in 1973 and worked it until 2007 without knowing that it had been bored out and was running without sleeves. I found out when I took it in for an overhaul that it couldn't be bored any more for new sleeves. That is when I bought a used block, had it tanked and fluxed and re sleeved. Thanks for all the info. Ellis
 
What year did you do this? The IH parts and accessory catalogs and M&W catalogs from the 1960's showed 4.00" bore for SM, SM-tA, 400. Only 450 got 4-1/8" bore.

Does your machine shop have a sonic bore guage?
 
Maybe this picture helps Just few sets from IH. IH had other types for 4-1/8 also. Blocks 356980R1 and R2 in C-264 and C-281 used in Farmall tractors had a casting number 356980R1 In SM to early 400 tractors, then 356980R2 in rest of 400 and 450. Only thing to watch if interchanging parts is the piston pin size. Serial break during 400 production the connecting rod pin end were made for a smaller pin. Previous rods and late rods were the same center to center and same size on crank end. IH made pistons for both size piston pins and some for different head combustion chambers. Some overbore pistons and others were sold with small pins for use with first type connecting rods and required a piston pin adapter bushing in rod end that IH sold. Example a 400 engine after the serial break would use the same piston set as a C-281. Before the serial break a C-264 could use the same set but need a thicker pin bushing in rod. Comparing gasoline engines a fire crater set piston can be different for a SM head than a 400 or 450 set because of head type used. Aftermarket made different combinations. M&W sold 4-1/8 sets for C-264 and C-281 engines and also a 4-1/4 set that required boring.
a258020.jpg
 
The serial number break was at 31,329 and higher had the smaller wrist pins on the 400 Tractor, and all the 450 had the smaller 1 in wrist pins !
 
I have the start of light weight rods as 31239 in a F-400, 31259 in a LP F-400, 2484 in I-400, LP I-400 as the next one built after 2484. Or all C-264 engines serial number 163808 and up. C-281 501 to last.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top