Hey guys I have a buddy who has a 68 charger with a 727 automatic. He swapped the 383 for a 440 and since the new engine was installed it has a constant vibration that seems to be coming from the engine or transmission. It happens all the time even in park so we know its not the driveshaft or rearend.

Any ideas on where to start looking to cure the problem?
Thank you
Stu

Wrong balancer, improper balance of the crank.rods..

Sounds like a converter issue to me.

If it's a cast crank 440 you need the external balancer and add the weights to the converter

383 and 440 use the same converter.. Does he have any history on the 440?

If it's a cast crank 440 it is externally balanced
that being said you need the cast crank balancer "it has an offset weight on it" and you need to add the weights to the converter
they sell the weights and templet and you just weld them in place

Thanks guys I will pass this info along!!

Yep, sounds like a external balanced engine without the counter balance weight. Oh by the way, don't run it till you get the weights on or you'll be doing a rebuild.

Yes, the 73 or so and newer 440's had cast cranks which does not mean that someone could not have updated to an internal or external balance steel crank either.

Or it could be a 440 6 pac engine with a steel crank , those were externally balanced engines also. Police car engines [ 440's ] back in the the day also had the 6 pac rods and pistons . Could be one of those engines. Run a scope down the plug hole and see what the top of the piston looks like.

Let's not get complicated here, the answer is very simple. Discussions of rod and/or piston weight muddy the water.

A '68 Charger 383 was internally balanced, so the converter is neutral balanced.

A 440 at this stage in life is as likely to have a cast crank as a forged one. In my experience, if one is looking for a decent used 440 the engine found will most likely have a cast crank. This is because the later 440s were not very high performance engines and the early ones have been hot-rodded preferentially over the years, making them scarcer.

Look at the Engine ID pad under the distributor. It'll tell you everything about how the engine was built. Dollars to doughnuts, there will be a letter "E" stamped somewhere on the pad. That "E" stands for cast crank.

I am now assuming the engine is a cast crank 440 that was swapped into the Charger in a simple unbolt-bolt manner. In this case the 383 torque converter was used with the standard MOPAR flexplate. Here is your problem.

The cast crank 440 requires a certain amount of external balance on either end of the engine. Assuming again that the harmonic damper was not disturbed, the rear end of the crank is now unbalanced and vibrates. A weight must be added to the rear of the crank.

Chrysler did this by welding weights on the converter.
Your friend can do it by swapping his stock flexplate with a special unbalanced flexplate. Converter stays as before.

B&M used to be the only ones who made this unbalanced flexplate, I think others do now, too.

Assuming again that the car was not a drag racer or daily driver, and it didn't see a lot of miles, the rear main bearing is probably OK, at least good enough to let the owner simply swap in the imbalanced flexplate and keep driving the car.

R.

Get the Engine ID number and post it. There are a few other possibilities that are not so likely, but the ID number will allow the Sherlocks here to ferret them out.

Possiably, As long as the motor was never rebuilt.
The numbers on the block will tell you what SHOULD be, not necessarily what is. I guess it could be another starting point.
The only way to tell if it is a forged or cast crank is from the casting lines on the throws.
You can also install the wrong Ba lancer on ether.

Thank you all for the great information! I will pass it all along to him.

I have done cars and watched others do cars for 45 years. What I described is how 90% of them are done.

Don't make this any more difficult than it has to be. When's the last time a civilian changed a damper?

OP, please post the Engine ID information. I, at least, am curious.

R.

I bet you'd be hard pressed to find a completely stock 440 that ran at all to do this install that you've watched happen for the last 45 years?
If it was the case He could just look at the damper and the convertor and Know what he had.
Apparently its not that easy.
Civilian? What are you even saying?

Good-bye.
R.

Check the balancer and the convertor for a mismatch.
Like has been mentioned earlier.
You can check the numbers on the block but Ive built many motors and used blocks that had both style cranks. They always ended up forged after I was done with them.
That is my original point..

I will get some info posted as soon as I see my buddy again. Thank you all!