Hopefully quick and simple solution...

I have a '76 440 engine mated to a '67 727 transmission and am having some vibration problems at I would guess around 1000 to 1500 RPM's with the car parked in the garage,at least that is where it is very noticable.As far as I was aware big block engine are balanced to themselves as are the torque converter in the transmissions,is this correct? Would the flex plate on the '76 engine have anything to do balancing?

When I installed the engine I had to swap out the original flex plate bolted on the crank with one from a 383 to match the bolts up with the converter on the transmission,could this be the problem? The flex plate is not damaged in any way that I know of and the torq converter and harmonic balancer appears to be good,transmission shifts fine.Vibration is in both "Park" and "Neutral" position...I had been told that maybe I need a '76 converter to match up with the engine and use the original flex plate...is this true? Thanks for any input...that vibration has bothered me for at least 5 or 6 years now and one of the main reasons why I haven't drove the car in that time.

you a externally balanced motor and are using a internally balanced motor's torque convertor

I'm sure it sounds silly to ask but this means that a '76 440 is not balanced to itself and must be balanced with the factory flex plate and torq converter in place?

Or better yet,all externally balanced engines must have a harmonic balancer on the front of the crank and must use the torque converter on the back for balancing?I thought this was only an issue on small blocks and big blocks were not setup that way?

Anyone know of a quick fix to the torq converter like on the smallblocks without pulling everything back out or is finding a new converter the best option?

B&M sells an externally balanced flexplate to use with a neutral balance converter. Cost about $80 if I remember right.

Yep, look here http://chucker54.stores.yahoo.net/bm1.html

Up until 1970 or so all
Mopar engines were internally balanced.
You call this balanced to itself.
Then the fun began. 360s are ALL externally balanced, forged crank 440s with the heavy rods are externally balanced, 340s, 383s and 400s with cast cranks are externally balanced, and cast crank 440s are externally balanced. Your 76 engine falls into that category.

Chryslers carried the factory imbalance on the torque converter AND the harmonic damper. The 67 converter is neutral balanced, thus
to use it you need a weighted flexplate as above, a cast crank 440 TC, or weld the right weights onto your 67 converter. The flexplate is easiest.

If your engine has a cast crank there will be the letter "E" stamped on the engine ID pad below the distributor.

By the way. did your converter nose fit snugly into the end of the crankshaft?

R.

That explains the issue...the only big blocks I have dealt with were all probably '68 or down so I never had the problem before.Thanks everyone for the info,I will check into the flexplate solution.

Honestly it's been a while since I dropped the engine into the car so I'm not sure about the converter nose question...I do remember it being one of the more difficult engine swaps overall as far as getting everything lined up just right.If there is a difference in the converter center sizes that would explain that as well.

67 i think, 66 and back has diffrent spline count

FYI, on the small blocks that flexplate will interfere with the mini starters and it will have to be ground but I forgot exactly where. Not sure if it's an issue on the big blocks.