Crank-Balancer-Flexplate?

[1969GTS340]

I need direction with a 340 I'm about to build. It was previously a marine engine that I'm converting rotation to use in an A-Body automatic. The crank had a flywheel and the balancer that was NOT stamped "Use with 340 cast crank only".

My first question is whether the crank is cast or forged? Although the block is a 73 I'm curious if Chrysler used forged cranks in their marine apllications. It looks very simular to a 69 340 crank I have.

Second, Will I need to replace the original balancer and match a flex plate to use with an automatic?

Thank you A-Body memebers.

 

[1969GTS340]

I need direction with a 340 I'm about to build. It was previously a marine engine that I'm converting rotation to use in an A-Body automatic. The crank had a flywheel and the balancer that was NOT stamped "Use with 340 cast crank only".

My first question is whether the crank is cast or forged? Although the block is a 73 I'm curious if Chrysler used forged cranks in their marine apllications. It looks very simular to a 69 340 crank I have.

Second, Will I need to replace the original balancer and match a flex plate to use with an automatic?

Thank you A-Body memebers.

 

[Locomotion]

I don't know if there are any little differences between marine and auto applications, but the photo below will help determine if it's cast or forged. Cars had cast cranks in '73 340's.

"IF everything else is the same, a forged crank would require a neutral balancer /damper and flexplate. But if you start changing anything, like rods & pistons, you need to rebalance. Factory balance jobs weren't very precise, just "good enough", so it wouldn't be a bad idea to rebalance everything anyway.

 

[Locomotion]

Looks forged, and provisions for a windage tray in a marine engine!

 

[nm9stheham]

Your balancer shown is not imbalanced.... like it would be for a cast crank. The front of a cast crank 340 balancer would have an obvious unsymmetical front flange.... like on the right in the pix in the 7th post here:
340 balancer question | Unlawfl's Race & Engine Tech | Moparts Forums

 

[whitepunkonnitro]

You may have an issue with the knurling for the rear main seal

 

[67Dart273]

I don't know about the balancer. LOOK CAREFULLY at the oil slinger serrations in the crank I believe you will find that the go the WRONG DIRECTION for a normal rotation engine

These are stolen off the www are for a normal crank

 

[67Dart273]

You may have an issue with the knurling for the rear main seal

I wuz' lookin' fer picchures and you were posting LOL

 

[1969GTS340]

Thanks guys, I'm glad to read that there is consensus on the crank being forged and the current balancer being neutral, I should just need a neutral flex plate and neutral converter to match.

The oil slinger serrations are indeed going in the wrong direction. I have read that these can be polished off smooth and not cause any sealing issues with the gaskets that are available these days. Again... if anyone has experience with this mod I'd like to hear how successful it was.

 

[Max1196]

Thanks guys, I'm glad to read that there is consensus on the crank being forged and the current balancer being neutral, I should just need a neutral flex plate and neutral converter to match.

The oil slinger serrations are indeed going in the wrong direction. I have read that these can be polished off smooth and not cause any sealing issues with the gaskets that are available these days. Again... if anyone has experience with this mod I'd like to hear how successful it was.

yes the width of the seal surface is wide enough to "erase " the directional oil pattern sealing surface with an available / competent crank grinder. I do this often just to aid in the conversion from an engine that had a "rope seal" to will be using a rubber style seal.