crankshaft help

[lhearold]

You can use the 273 forged crank and depending on what pistons you choose may be real close on baslance. Ther is plenty of area on the counter weights to add mallory metal to balance if needed. Just be sure that you choose a good machine shop. As for using a 360 crank, I did that years ago but you will need to turn down the main bearing area to the 273/318/340 size and then internally balance with mallory metal. If I remember right the machine shop I used actually had to remove a little from the counter weights during the balance but then again I was using a 318 block.

Larry

 

[cudamark]

All the '62-91 273, 318, and 340 cranks will bolt into your block. All 3 had forged and cast versions. All will work fine for your horsepower specs. You'll have to balance everything no matter which one you choose. Here are other considerations:
'62-early '67 318 Poly......steel crank
late '67-91 both steel and cast iron available
'64-7 273 steel but small converter button hole (man. trans no problem)
'68-9 273 cast crank with large convertor hole
'68-early '72 340 (April 1st I think) steel crank
Late 72-3 340 cast crank externally balanced
The 273's all had the light weight rods.
318's had light and heavy rods depending on year and application
340's all had heavy rods
Whichever one you use, check the thrust bearing surface for wear. It's an often overlooked area that can add to your machining costs if it needs to be welded up.
Mark

 

[moper]

You could spend money on anything you feel like. Cryo treating for your level of performance isnt needed even with a cast crank. Save some cash. Just find the crank and have it turned/polisheed/balanced and go have fun...