This is for 340 builders

Just make sure the convertor fits into the hole in the crank. I used a 273 HIPO crank in a 340 and the convertor didn't fit the crank.

I was young and STUPID. I made it fit, but it had a vibration. After checking the crank rod & main journals I thought all was OK, but it should have been balanced.

If I were to build another 340 I would go for a stroker crank. If you have to have much machine work on the crank the little extra will get you a new stroker crank. And unless you are going to build an extreme engine you don't need the forged crank.