balanced flex plate on balanced 360 cid

Double check that you have the correct flex plate and that your harmonic balancer is correct as well. For instance, The 340 and 360 have different balancers and one will not work with the other. The other balancing factor to consider is the torque converter.

There are a couple ways you can go to properly "balance" the engine.
You could use a stock Flex plate on either SB engine but you would then need a balanced torque converter specific to each engine. The easiest route would be to buy a specially balanced flex plate specific to the 360, which you have done. If your harmonic balancer is correct, then Once you have the back end of the engine balanced with your B&M flex plate, you can use a neutral or zero balanced torque converter which is much more affordable and available

So,
Make sure you flex plate is for a 360 not a 340
the 340 balanced flex plate is slightly different than the 360 balanced flex plate.


Make sure your harmonic balancer is correct. the harmonic balancer for the 360 has a funky shape to it. It is "weighted" to balance the engine as it goes round and round.

If both your flex plate and you balancer are correct, then perhaps your torque converter is not the neutral balanced one you need. If it is specially "balanced" for a different set up, it would throw off your engine. In other words. If you use a B&M flex plate and the correct harmonic balancer, your torque converter should be zero or neutrally balanced.

When either of these things are out of whack you will know because the engine will wobble at higher RPMs when you are in park. If what you are feeling is a slight vibration in the wheel and not a violent shake, then your vibration lies elsewhere. You need to simply start troubleshooting and eliminating. Check engine mounts. Are the bolts all tight? Are the rubber bushings still good? Is there metal touching metal?. Are your tires good to go? Vibrations are a search and destroy symptom and take alot of patience. I found my vibration problems in the transmission mount. But you will find yours! drive on my friend.
thanks and God Bless
Keni