Crankshaft question

[d240zx2]

My old '70 was built back when Datsun was using 5 counterweight crankshafts. They're good and solid....up to a point. That point being about 7500 rpms. Then they pull the amoeba trick and become a two-piece crankshaft.

After this problem was discovered, it was corrected by installation of 7 counterweight cranks. Problem solved....go for 8 grand or higher.

Question: What modifications to the block are required to install a 7-CW crank in lieu of the 5-CW OEM crank? Any other parts or pieces that need to be changed?

[Phred]

Wow, I've been building engines since those first came into the states, and I've only seen one, and it wasn't in an engine. I thought they had all been broken or replaced. I remember reading the BRE cars broke their eary cranks, before the later style was available. I believe the later cranks are a direct replacement fit.

Phred

[d240zx2]

Thanks, Phred.

I'll check with Nissan to see if the 7-CW cranks are available still.

[e_racer1999]

hahaha... amoeba trick....