I'm trying to sort through some facts about the SM, 400, and 450 engines. As I understand, the SM, 400 and 450 all used the same block. More cubic inch (281) was generated by using thinner sleeves in the 450 block. My neighbor insists that the early 400's came out with the 262 engine and the later ones came from the factory with the 281 engine. Is this true? Also What would be the cubic inch of this engine if it was fitted with 4.25 pistons such as M&W sold? Did M&W sell 4.12 pistons also? Marv

4.25/2=2.125*2.125*5.25*4*3.1416=297.912 or 298 cu in. D Slater can answer your other questions. IH did sometimes "jump the gun" by putting some of the new models features on the older model. If true, ask your neighbor if it had C281 cast into the block.

Thanks for the reply. My neighbor's 400 does have the 281 stamped on the block. However, He bought it used so it could have been upgraded. Personally, evey 400 I've looked had the 281 stamped on the block. I'm still looking for a 400 with a 262 stamped on the block.

No way I can say for sure that some of the very last 400 tractors made were not equiped with 4-1/8 pistons when new. But unless the 400 is over serial 41000 I don't think there's much chance. 400 blocks don't have C264, yes C-264 stamped in block. Originals have the size in cast raised letters and numbers. Also original C264 blocks into early 400 have a block cast # of 356980 R1. Most original 400 all 450 blocks had 356980 R2. Some replacement block had other cast numbers. Nothing I have ever found shows 400 tractors produced with 4-1/8 pistons and sleeves for resale. They probably put some in tractors for testing before releasing the 450 and some may have been sold. IH was selling replacement increased bore piston and sleeve sets for 400 tractors around November of 56 anyway. If all you can find is 400 tractors with C 281 on them you must have a bunch of engine changes in your area. Be interesting to know what the date codes on the blocks is. Also is there a serial # on blocks. IH was selling replacement blocks at least 10 years after 1958. M&W 4-1/4 stock stroke is 298 CI. With there 5-3/4 crank and 4-1/4 bore, 326 CI. Serial numbers for C-264 blocks started with SM tractors and ended with 400 tractors. C-281 engines started over with serial # 501. Like to know date code and serial # on block your neighbor has.

Marv yes M&W sold 4.125 pistons. Also didn't mean to give the impression that all SM through 450 blocks are 100% the same. Just that same sleeves fit all the blocks and 4 inch or 4.125 inch piston or sleeves can be used in any of the blocks as long as the different piston pin sizes are matched to connecting rods. Farmall 400 C-264 engine made the change to small piston pin connecting rods on engine serial # 163808. all higher engine numbers and 450 C-281 used same rod. Hope this answers questions and if not or you see something wrong, ask away.