340 Vs 360

I thought this thread might be fun to drag back from the dead. Since I am a Molnar Technologies dealer I will add these thoughts.

Currently Molnar list 6 different variations for a 340 main journal with 3 different rod sizes available.

While they only offer 2 different strokes for a 360 main journal. 3.79" / 2.100" rod journal and 4.00" with 2.125" rod journal.

So your asking why does this matter?

Well if you're going to build a race stroker 360 with a 4.00" stroke crankshaft you are limited to using 6.123" long rods because of the 2.125" rod journals.

If you're using a 340 block you can buy a 4.00" stroke crank with 2.100" Chevy journals that accept off the shelf rods available in lengths up to 6.300" long.

Because a SBM has a really tall 9.60" deck height when using a 6.123" long rod in a 360 with a 4.00" stroke crank you end up with a 1.477" compression height

and a rod stroke ratio of 1.53

If you use a 340 block with a 4.00 stroke and a 6.300" long rod you can end up with a piston that has a 1.30" compression height and a rod stroke ratio of 1.575

The 340 has a 2.50" diameter main journal and the 360 has a 2.81" diameter journal. Fun fact: All NHRA Pro Stockers also use a 2.50" diameter main journal.

Just some food for thought when you are deciding if your next project is a semi race engine or a real race engine trying to gain every horsepower available.

Tom