I bought a Balanced Rotating Assembly part number B12107030 back in 2005 from Combination Motorsports who I think are not in business anymore. After building the engine, I installed an external balanced flexplate part number TCI Auto 399173. The flexplate failed because of the powder coating that it had on it in the bolt hole area. Now that I have taken off the flexplate I think that the Balanced Rotating Assembly was internally balanced since it did not come with a damper or flexplate. Is this right? If so, should I now go with an internally balanced flexplate? I don't think there is any engine damage but I don't know for sure. I have had an oil leak for some time from the oil pan but not sure if that is related. What are my options at this point? The enine was assembled back in 2005 but only has about 3200 miles on it. Any help would be greatly appreciated. I can provide other info if needed.

 

i believe this is your kit...http://summitracing.com/parts/ESP-B12107030/

atleast the eagle part numbers match up.. you do need a neutral balance flexplate with that kit...

have you ran this with the counterweighted flexplate for 5 years? if you have, its a wonder you havent beat the bearings out of the engine yet... your other flexplate may have failed because it was out of balance..

if you did run it that long, did the engine seem to shake/vibrate alot?

 

Take it to a local engine shop and have them order the right one for you.

Most, but not all, full round rear seal 350's are externally balanced on the rear, and neutral on the front.

 

Yes I have run a weighted flexplate for five years now but only 3200 miles. It does have some shake to it but it does have a decent size cam. Should I change now?

 

i think the details on that kit said it was neutral/internal balanced.. so you would need a neutral balance flexplate..

if you are running the stock counterweighted flexplate, it would throw off the balance of a neutral weighted assembly..

you might contact eagle to check the part number and verify how its balanced..