Fordiesel69 233 #1 Posted June 20, 2012 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? Share this post Link to post Share on other sites
MarkPalmer 80 #2 Posted June 20, 2012 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- Share this post Link to post Share on other sites
Fordiesel69 233 #3 Posted June 20, 2012 So the block and crank are different??? I have no experiance with the K161. Share this post Link to post Share on other sites
MarkPalmer 80 #4 Posted June 20, 2012 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- Share this post Link to post Share on other sites
Fordiesel69 233 #5 Posted June 20, 2012 You're right, definalty not worth the extra 1HP. Share this post Link to post Share on other sites
sorekiwi 761 #6 Posted June 21, 2012 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. Share this post Link to post Share on other sites
Rooster 191 #7 Posted June 22, 2012 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? Share this post Link to post Share on other sites