72 340 balancer
- Thread starter dad69dds
- Start date
-
Professor Fate
Push the button, Max...
Early '72s were forged crank and used the internal balance balancer.
Late '72s went to an externally balanced cast crank (and lower compression and smaller 1.88 vs 2.02 valves) and used the "cast crank 340 only" balancer.
The changeover came sometime during mid-year, so it depends on what crank you have.
Late '72s went to an externally balanced cast crank (and lower compression and smaller 1.88 vs 2.02 valves) and used the "cast crank 340 only" balancer.
The changeover came sometime during mid-year, so it depends on what crank you have.
The only sure fire way to know is to get the pan off and look at the crankshaft.
I have no idea what the rules were supposed to be re cast/forged crank in 72 340s (and I'm not sure they were consistently followed anyway), but the first 340 I put in my 65 Barracuda back in 1973 came out of a wrecked 72 Charger. It had a forged crank, with 8.5 pistons and the small 1.88 intake valves. Balancer was the neutral-balance forged crank unit.
I never saw the Charger; my Dad bought its motor while I was on a destroyer off the coast of Viet Nam. My understanding was it was an automatic car, but the crank was machined for a pilot bushing, so it may have been a 4-speed (or 3-speed manual). Whether the transmission made any difference on which crank a 340 got that year, I have no idea about that, either.
If my Elderly memory serves me = All Stick 72
340 cars had the Forged Crankshaft.
340 cars had the Forged Crankshaft.
Musclesigns
Well-Known Member
I have an extra forged balancer and p/s crank pulley for a 72 340 if you decide that’s what you need.
The cast cranks started in about April of 1972.
My 340 Demon 11/71 build date is a forged steel crank motor- 4 speed car.
Every early 72’ 340 motor I own has a forged steel crank.
QQ: do you not have a balancer at all for your engine or does your engine vibrate badly? Send over more details why your asking - it may help us help you.
Every early 72’ 340 motor I own has a forged steel crank.
QQ: do you not have a balancer at all for your engine or does your engine vibrate badly? Send over more details why your asking - it may help us help you.
You might be able to see enough of the crank to identify by pulling the timing cover. That would certainly be easier than pulling the pan. I have had a lot of 340's and most 72's I have seen were cast crank. No guesswork here, your going to have to visually inspect the crank and find out what you have.
RustyRatRod was correct in that it started about april. here is a pic of the parts book note in my 1972 factory parts manual. tried to get the best pic i could.
I have a vibration at idle
Musclesigns
Well-Known Member
I had my original balancer rebuild a few months ago. Great service and reasonable price. Two week turnaround.
DamperDoctor
DamperDoctor
Okay- vibration at idle. Stick car or auto car? Recent tune up or what. A vibration at idle could be many different things.
Pull it up to "around" 2000 RPM. If it's an imbalance vibration, it should rattle your fillings out about right there.
I agree with Rusty. My experience with out of balance motors on the dyno is that the vibration is most noticeable at speeds slightly above idle. The vibration may even diminish somewhat above 2000ish.
If it’s an auto car and cast crank it should have weights on each side of the drain plug on the converter. This is how I check for a vibration. I lean over the fender with my belly resting on it. Rev it up some. While the revs are coming down u will feel it vibrate. Kim
The change over was at a certain engine number. It is posted on here somewhere but I couldn’t tell u where. Kim
Yes it has a balancer The car is a 72 duster 340 auto on the floor number matching 8.5 pistons j heads with 1.60 and 1.88 intake had a vibration at idle didnt pay much attention about it at first when i got the car. i put a little bigger cam than stock and added some u heads 1.88 with 2.02 intake valves still had a viberation at idle or should i say the motor shakes. So I had the motor rebuilt 40 over pistions with a new cam lifters same u heads when i got it back got it running still have a shake. new plugs, wires, distributor, new control module checked the wires going thru the fire wall ive had several mechanics look at it no body can figure it out even the guy that built the motor. Two diffrent carbs eldbrocks 650 new. It will smoke the tire when u get down on it but idles rugh and dies as u stop at red light. i have set the timming every where now its around 28-. I replaced the motor mount on drivers side and now im going to do both. Some friends have cams much bigger than mine and there motor idles smooth Not sure on the cam specs, ill try to find out but its less than 500 lift. Ill ask the shop that built it what crank is in it.
Last edited:
Did u have it balanced? What cam. Do u have adjustable rockers?
What's the fear of getting the pan off and finding out for 100% sure? Do you think they'll really know? I wouldn't trust them or anyone else at this point. If they built it, they put the wrong balancer on it. Why the hell would they know anything? It's not a difficult job to do yourself and then you'll be 100% SURE of what you have.
I was going to build it my self but i had someone wanting to swap out some work and thats what i diid i told my wife that i shouldve done it my self i have a shop and a lift so i guess i will have to do that.
You might be able to drain the oiĺ and bore scope it to see if it is a forged crank without pulling the pan. Worth a try.
-
