Hello Everyone,

I am going to be swapping my V6 for a 350 TPI very soon. Now my question is how do i know if an engine is internaly balanced or externaly balanced? The 350 I have is just a Block and heads that i pulled from an '87 GMC Sierra. And i need to get a new harmonic balancer because the one that is on the engine now looks broken. Any help would be great.

 

It is internal balance, all of them are except 400's and strokers.

 

True, but some strokers are internal balanced too.

Any GM-built small block engine other than a 400 will be internally balanced though

 

if it's just a block and heads it has no balance. the balance is in reguards to the rotating assembly, which is stock would be internal balance.

 

he said it's out of an 87- 1 pice rear main seal- they are externaly ballanced for all appclations, but only slightly and only on the flywheel/flexplate side (unlike the 2 peice rear main 400, which has a counterweihgted ballencer and flywheel/flexplate), that's why the bolt patteren changed when they went to the 1 peice.

 

all SBCs are internally balanced, except the 400. what gets people mixed up that don't have a good handle on engine balancing is the bat wing weight on the flex plate that replaces mass from the flywheel mounting flange