Can K161 7HP be overbored to 8HP piston?

[Fordiesel69 233]

I have a 7HP model of this engine. Can it be bored to an 8HP piston or is there other differences like stroke or crank balancing?

[MarkPalmer 80]

The 7 HP K161 and 8 HP K181 actually use the same 2.938" bore. The stroke on the K181 is longer at 2.750 opposed to the K161's 2.50"

-Mark-

[Fordiesel69 233]

So the block and crank are different???

I have no experiance with the K161.

[MarkPalmer 80]

I know at least the crank is different as the 181 has a .25" longer stroke. One thing I don't know is if the actual blocks are different or not. The 161 uses a longer connecting rod to make up for having less stroke, so its possible the blocks are the same. I do know the 181 cam is different from the 161 also, as its center is notched out for the additional stroke so the rod does not contact it. There is a rare, early spec of the K161 that uses a smaller 2.875" bore than the K181 so you have to measure what you have before attempting any parts swaps. I would be interested in knowing if a K161 could be "stroked" in to an 8 HP, I don't see any info of anyone having tried it, I guess no one figures the added 1 HP would be worth the trouble.

-Mark-

[Fordiesel69 233]

You're right, definalty not worth the extra 1HP.

[sorekiwi 761]

These days I think its more a case of building an engine to suit the parts that are available rather than looking for the extra 1 hp.

I have one of those early small bore blocks here, one day I'll get around to seeing if it can be bored for the bigger piston, as its very hard to find one of the early small ones.

[Rooster 191]

Yes the early K161 can be bored to The new"ER" spec.

Yes the K161 will hold a K181 crank, but as mentioned before you will need the K181 Camshaft. I am not sure on the rod to use with this swap though?