Went to put a converter in my 68 340. Motor has a forged balancer on it but found the converter has weights. Block appears to be a 72 but has been rebuilt by previous owner who I can't locate anymore. Anyway to figure it out??
Internal or external.
- Thread starter dgibby
- Start date
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Bulldozer
free ice cream sandwiches
you can drop the pan. this shows a 440 crank, but you get the idea
moper
Well-Known Member
Where are the weights on the convertor? If they are on the outside and are thin flat steel - welded on the circumference of the shell - they are simply to make the convertor neutral. If there are weights on the hub side - the flat where the flex plate bolts to - it's to balance the crank.
I took off the dust shield and could see weights on the side that faces the block. I drop the pan and think it is a forged crank but i can't really tell. it looks pretty rough to me, like poor casting but the various numbers are all stamped in it not cast. the parting lines are also wide. here is a link to some photos that I took. some are not the best but you can double click and zoom if needed.
https://www.icloud.com/photostream/#ACGrq0zwhuoqQ
https://www.icloud.com/photostream/#ACGrq0zwhuoqQ
Mad Dart
Nothing to see Here!
What kind? There are several balancers out there that can be used for both. Are there any weights on the back side of it? Grab a flash light and look if you can. They will be held on with bolts of some sort if there is.
Bulldozer
free ice cream sandwiches
that's definitely a forged crank. im going to say someone is/was using the wrong converter. I bet that puppy had a nice vibration. knock the weights off the converter and use this balancer
That pretty much looks like the balancer that's on it. I have a new internally balanced converter to put on, just want to make sure it is the correct one before start. Does have a bit of a vibration, best I can describe is like a bad u- joint/driveline vibration.
moper
Well-Known Member
Does it vibrate in park or Nuetral when you slowly bring the rpms up from idle to say - 4500? Does it get worse with the higher rpm?
Park/neutral seems pretty smooth, never took it up to 4500 though... I notice it at freeway speeds around 3000 rpm and up. Goes away when I put it in neutral driving on the freeway. Isn't really that bad, but I always thought it shouldnt be there. Like I said, kind of felt like a bad u-joint or driveline vibration, even thought maybe a wheel bearing. I've got to drive the car about 60 miles to get to the shop that is going to do the new converter so I'll knock the weights off the one that is in the car and see if it goes away for the drive down.
moper
Well-Known Member
The question is, when it goes into nuetral - does it drop to idle where you don;t feel it. Before you knock weights off do the park/nuetral test. If it shakes, then knock them off. If it doesn't, don't assume the internet is right and the guy that built it wasn't. There might be a reason it's got weights - like if the engine was balanced by a shop that included the convertor, flexplate, and harmonic dampener.
60 miles of bad vibration can seriously damage the engine.
60 miles of bad vibration can seriously damage the engine.
yes, it drops to idle and goes away and when I put it back in gear its back. I will check it in neutral/park this weekend and see if I can tell. How bad would the vibration be? I mean it's fairly mild, I've driven cars with out of balance tires that are far worse than what I am feeling. I dont really understand converter but wouldnt it have to be in gear for the converter to be engaged for it to vibrate? He could have had the converter balanced to the motor but it seems like the stock converter that is not even close to what the motor seem to be built for. Unknow mopar purple cam specs but the range seems to be 2800 to 6200 rpm. Converter seems to stall at 2200 max. Seems like a waste to balance a motor to a converter that isn't right for the car..Don't know.. the guy seemed to do alot of stuff right on it but also seemed to half a#$% alot on it.
No, the converter is bolted to the flexplate which is attached to the engine. That's why you need to determine whether or not it is doing it in neutral.
If it has vibration in neutral/park then you have isolated the problem to the engine/converter.
If it does it in gear and going down the road it would tell you driveline, bad tire, out of balance tire/wheel, bent wheel etc.
moper
Well-Known Member
yup - and if it's not the engine you're fine. Sounds like it's not...
Well, gave it a rev-tune in park up to about 4000 rpm and oh yeah...shakes like a bitc$% at idle it feels more like a mis-fire. going to knock the weights off and see how it feels. This is my first mopar/hot rod of any kind and had not idea about internal/external balance until I started looking for a new converter. Unfortunately have put about 800 miles on the car with the wrong converter in it....guess we'll see how it goes. Thanks for everyones input.
Mad Dart
Nothing to see Here!
Did you look behind your balancer?
Mad Dart
Nothing to see Here!
No other weights then. You gunna knock off the weights with the converter in the car or take it out?
I am going through the same thing except my car is a 73 with a 73 340 in it which is supposes to be one of the only years with a cast crank and External Balance for the 340. I bought the car about 2 months ago and have been working out the bugs ever since. The converter has the weights busted off and there is a B&M Flex plate with the half moon missing to simulate the counterweight on the converter. I have a Professional Products balancer with the weight bolted behind the balancer. I have a slight vibration like yours from about 1500 Rpm to 3000 rpm. The transmission took a crap so it is out and torn apart on the bench. When they busted off the weights there are Huge chunks of weld still on the converter so I am thinking that is why it vibrates. Trans is being beefed up and a new Neutral balance high stall converter is going in it. This will hopefully fix my problem.
So if you are going to leave the trans in the car and knock the weights off. Just be aware that you still may have a vibration from the welding slag that is left.:banghead: If you take it out you can sand them down smooth and get rid of the slag.
Mad Dart
Nothing to see Here!
Already got them off. Quick little hit with the air chisel and they came off clean. Vibration gone!!
Damn...... good for you!!:thumbup:
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