I have a problem with my '69 Charger R/T, and I hope someone can help me. The car's engine has what I would describe as a fairly strong vibration. It's taken all the fun out of being able to drive the car again.
This Charger is the car I bought in November 1970 when I returned from Viet Nam, so there is no way I could adequately describe what the old car means to me. It had been tucked into a corner of my garage minus an engine and transmission for 12 years. In an effort to get the car back on the road again, I had bought a strong running 440 and 727 transmission from my son's friend several years ago. It's a rebuilt '76 440 that my son's friend had in his '67 Coronet R/T while its original engine was being rebuilt. The 727 has a shift kit and a tweaked valve body and works great.
Last fall my son and one of his friends installed the engine and trans into the Charger so we could take the car to Monster Mopar Weekend. The engine was previously rebuilt. I don't know if it was bored or not. (I don't have any specs on the rebuild.) I do know it has a set of 906 heads with double valve springs and a mild RV cam, as it was supposedly built for towing in an older Dodge Ram pickup. It has a 1970 cast iron intake manifold. While it was on the engine stand prior to installation I installed the HP exhaust manifolds that are original to my Charger. I also installed a rebuilt water pump and a '69 water pump housing. The engine uses a stock points-type distributor with a Pertronix setup. The carb is a Holley 750 double pumper with mechanical secondaries. It has a correct Saginaw power steering pump mounted using a set of Bouchillon reproduction brackets. A '69 air conditioning compressor was also installed. We used new stock (rubber) motor mount insulators and a new stock (rubber) transmission mount.

The engine had a B&M flex plate bolted to it, as it still retains a cast crankshaft and thick dampener. We installed the engine and trans into the car with a new aftermarket stall converter (approx. 3500 rpm stall) using the B&M flexplate. This same steup (minus the new aftermarket converter) worked beautifully in my son's freind's Coronet R/T; in fact, I was convinced I should buy the engine/trans because it ran so well in the Coronet without even a hint of vibration. However, after installing the same setup in my Charger and firing it up, it was obvious the engine had an unwanted vibration. Suspecting the aftermarket converter, we begged the use of a lift, pulled the transmission and swapped in a known good stock converter from a steel crank 440 a friend of mine had on his shelf. Because of the cast crank in the 440 and the now stock steel crank converter combination, we retained the B&M flexplate. All that effort for nothing, as the vibration remained, with no change whatsoever. We went ahead and took the car to Monster Mopar and had a blast, in spite of the damned vibration.

We're stumped. The engine vibrates at all rpm, both in gear and in neutral. It's a pita to borrow a lift and pull the transmission (again), but I will do what I gotta do. The engine is strong as hell, starts and runs well and the transmission chirps the rear tires on the 1-2 shift. I want to be able drive this old car again, just like I did 39 years ago, but NOT with this vibration. Any and all suggestions would certainly be appreciated. (Sorry this has been so long.) Thanks!

Steve

It was an interesting read. Pull the trans again & get the right TC/flexplate for your externally balanced cast crank 440.

If it ran good before, the only thing it can be is a wrong flexplate/converter combo. A cast crank uses a weighted converter from the factory so now you can either run a weighted converter w/ non-weighted flex plate OR a non-weighted neutral balance converter with the weighted B&M flexplate.

Also, B&M also makes a NON-weighted flexplate. So is it possible you were using a non-weighted flexplate with a non-weighted converter? That would also cause your balance problem if you think you've got the weighted flexplate but really don't. After all, 0+0=0 and doesn't give your cast crank the counter balance it needs.

The other possibility is you're using a weighted flex plate with a weighted converter, but unlikely because you can see where the weights are welded to the starter drive gear on the converter.

B&M makes a flex plate that will cure your vibration... You have a cast crank 440 which is externally balanced & requires a counterweighted torque convertor or a special flexplate... Kinda like the one in this link...

http://www.summitracing.com/parts/BMM-10237/

So get the flexplate, get your car fixed & see if you can't find a few memories...

This was the same problem my Charger had when i bought it. In fact, it was half the reason i got it so bloody cheap... "The engine needs a rebuild". Well, i rebuilt that engine by replacing the converter. Mine had a weighted ('72 400) converter behind a internally balanced '72 440.

Driveline vibrations take all the fun outta driving, and left long enough they'll shake the hell outta your car till its got more problems than you can list.

Yea you need the flex plate with the big Pac Man bite out of it or weights on the converter.
is the harmonic balancer tight?

Also need the correct engine damper with the external weight.

Double check the firing order

Double check that you have the correct B & M flexplate. As has been said, you need the one with the half moon cutout in it to run a neutral convertor behind a cast crank motor.

Update: We (my son and I) have made the following changes to the car, and the engine still vibrates. Hopefully, we're at least closer to a solution.
We removed all the drive belts from the engine, eliminating the PS pump, alternator, water pump and A/C compressor. Fired it up, with no difference at all, still vibrated. It was then suggested that we replace the torque converter with a weighted TC.
We pulled the transmission, TC and flexplate. We reinstalled a brand new weighted TC which I ordered specifically for a '76 cast crank 440. This was installed using a factory flexplate. After buttoning everything up and starting the engine, the vibration was still present,and is possibly slightly worse than before. Sitting in neutral at idle, the steering wheel even visiby shakes. Just as before, the vibration is apparent either in neutral or while driving. We figure the only other possible suspect now is the (factory) balancer. We were told that if the engine was "zinged" pretty good before we bought it, the damper could have slipped. I started checking around for a replacement balancer (local parts places, Summit, Jegs, Mancini, etc., etc.), either stock or aftermarket. Damper Dudes in CA was the only place I could find a damper for a cast crank 440 - and even at that, the Damper Dudes guy said he did not have my damper (square cut ring) in stock, so I would have to send him mine to be rebuilt(it only takes him 1 day).
I know there are quite a few guys running street/strip cast crank 440s - what are they using for a balancer? I don't plan to turn my engine past 5500 (or so) rpm, so I assume a rebuilt factory balancer would be sufficient. Does anyone have any other suggestions? It never even occurred to me that finding a proper balancer would be such a problem running a cast crank 440(!). Thanks again for your help/suggestions.
Steve

I have the same problem with my 360. I also went thru changing out the tourque converter several times (to tighten up the stall speed mostly) and hoped to fix the vibration after doing a B&M weighted plate and zero balance torque converter from Shaun @ "whatever that top converter companies name is"
I finally had the drive shaft balanced and new u-joints and that appears to help a LITTLE bit but still not completely.

What is interesting also I find it only seems to vibrate under load. Once the converter kicks in and under load (pedal to the gas) and SEEMs to get worse the higher the load.

I am also thinking my problem is with the damper as that is where I am going to work on next.

good luck.

Could be a bad cam lobe?? /compression issue?

I have had this problem with my 340 rebuild. It has a externally balanced crank. I was finally told here and from others.That since my engine builder swapped out the stock rods and pistons for Eagle rods and Keith Black pistons. It messed up the balance of my crank.(can't believe my engine builder let this go). So my motor is out tore down and being sent to be balanced. Did your rods and pistons get swapped on rebuild for after market rods and pistons?

Thanks RemCharger and old340dog for your replies. I had not considered a wiped cam lobe. A compression test would be a good idea (duh!). I really know nothing at all about the engine's rebuild, as I bought it from my son's friend, and it was in a pickup he had bought just for the engine and trans. He was told it had been rebuilt for use towing a travel trailer, and had about 40k miles on it. I do know it has what sounds to me like a mild cam, and double valve springs. I only pulled the valve covers and swapped the truck oil pan for a 402 pan and added a windage tray. What I could see of the engine internals looked clean as a pin. The thing is, my son's friend had this engine and trans. in his '67 Coronet R/T, and it ran great and made all kinds of power. It sat on an engine stand in my garage for 3 yrs. before we installed it in my '69 Charger R/T. It vibrated like hell from the moment it was started for the first time. All I did to the engine, besides valve covers, a windage tray and oil pan swap was clean and paint it. It's as though something on it screwed up while it was sitting on the stand. Wierd. It's now on its third converter and second flex plate, with no change. Replacing the harmonic balancer is the only thing left to try, as far as I know. I just don't get it!
Thanks again

I had a cast crank 73 440 rebuilt, vibrated so bad it would tear up convertors and front pumps on like 5 different 727 transmissions, i checked several times and verified correct weighted convertor and flexplate. I took the engine out and pulled the main caps...the bearings were wore bad...looked like a 200k motor..and engine actually only had 10k on it. Being frustrated with this engine I installed another 440, no more bad vibes.

YOUR RUNNING LIKE A SCARED CAT AND MAKING WRONG MOVES!just calm down,i just fixed this problem on my 69 r-r 440,mobody can tell you ,i had to figure this out,my car has a 73 cast crank 440 viabrated like hell,what i did was fist wnt to 440 sources websight,looked at his explanations of diff balancers,made sure i had a cast crank balancer,then had to figure out that chys only balanced ther engines by the converter(by putting weights onem)since there are so many aftermarket converters out there,thy had to figure somthing else ,so b&m makes the flexplate wit the bite out of it,you need that with a non weghted converter,plusthe idiot on mine didnt have any dowels on the motor,had to get them,now the thing is butter,so use the b&m (bite out)plate not the one that lookes like a bow tie,any o balance conv you want and make sure youre dowells didnt fall out,cause you cant just hang the trans on the bolts,and you will be fixed,if you want to get a new cast balancer get it from 440 souse,tell him you have a cast motor,thats it,i telling you this only cause you said it ran great before,engines that run usually never go bad sitting on a stand,see you at mmw-jeff-314-303-2044

Hey graphix,aside from having low compression,a flat cam lobe,incorrect firing order or a bad miss.It does to be a incorrect t/c and plate combo,,the B&M plate you need is # 10237,has no weight,has a half moon taken out on one side,,,and the convertor should have no weight whatsoever.Good luck.