vibration off idle

Lilbluecoupe71

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I have a 1971 300 with a 440 in it. I recently had it rebuilt last march and have finally got around to getting it running. my issue is it still has a vibration off idle, it gets pretty bad around 2500, and begins to smooth out at higher rpm. this occurs without the car even moving. the car had the vibration before the rebuild. my father installed a reman transmission from a local parts store maybe 10yrs ago. the torque converter has some weights on it. my question is, does this 440 need weights on the converter? the block has a casting stamp of 2536430-9 dated 5/15/69 on it. does it make it a cast crank, or forge crank engine? what requires what for proper balancing? im thinking the converter has a balance problem and am not sure which converter to purchase
 
I have a 1971 300 with a 440 in it. I recently had it rebuilt last march and have finally got around to getting it running. my issue is it still has a vibration off idle, it gets pretty bad around 2500, and begins to smooth out at higher rpm. this occurs without the car even moving. the car had the vibration before the rebuild. my father installed a reman transmission from a local parts store maybe 10yrs ago. the torque converter has some weights on it. my question is, does this 440 need weights on the converter? the block has a casting stamp of 2536430-9 dated 5/15/69 on it. does it make it a cast crank, or forge crank engine? what requires what for proper balancing? im thinking the converter has a balance problem and am not sure which converter to purchase

There are two different torque convertors for the 440 engine. One is for the high performance, Magnum or TNT engines, typically U-code for your '71 (or V-code 69-70 6BBL, not available on Chryslers) motors with an externally balanced forged steel crankshaft, these use weights on the convertor. The T-code steel cranks are internally balanced and do not use a weighted torque convertor. As your motor has been rebuilt, the casting numbers may not be much help because all 440 engines used the same number from '66-72. Hopefully when the engine was rebuilt they were bright enough to install the same type of crank. That motor was produced late in the '69 engine run so it was not likely the engine that came in the car which was produced in '71. You probably had a TNT engine in the car from the factory with the forged crank. My guess is someone replaced that engine with a T-Code motor and the torque convertor is now wrong for the application. Remove the crank pulley and look at the front of the harmonic balancer, if it has a round center, you have an internally balanced engine. If the center of the balancer is egg shaped, the engine is externally balanced. All of this assumes that the balancer on your engine came with the replacement engine. As a rule V-Code (69-70) and U-Code motors were hemi orange in 66-71. If you have a Turquoise motor, it is a T-Code. Hope this helps. The best way to know for sure which crank is in the engine would be to remove the pan, a PIA, and take the number off the shaft and see which crank you have. If you have a mis-matched unit do not run it until this issue is fixed as vibration will destroy the lower end of the engine.

Dave
 
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the machine shop I used reused the factory crank and rods. he installed some new pistons to bump compression up. He said he balanced the rotating assembly. Here's a pic of the balancer.

20180319_153800.jpg
 
That is a T-Code balancer, you do not need a weighted convertor with this motor. Order a non weighted convertor. Did you also install a higher performance cam with the compression upgrade? You may need a higher stall speed convertor if this is the case. Check the stats for the cam and order the appropriate stall for the convertor.

Dave
 
The 274 Extreme energy cams are designed for 2000-6000 RPMs. I would suggest calling their technical support line with your gear ratio and the type of driving you plan to do. They are usually very helpful. I think you will probably need a convertor in the 1500RPM to 2000RPM range but talk to them before you order one. They will also want to know what type of exhaust you are running as this will effect the performance of the engine. You will also be wanting to do a band adjustment and transmission service as you now will be adding significant more stress on the transmission due to increased horsepower and torque.

Dave
 
You might try just knocking the weights off of the existing converter, but if you have that cam, you might aim for a '68-'70 Road Runner 383 application torque converter. Might be the same as for a Slant 6 727 application, too. Should be the 10.75" converter rather than a 11.75" converter, too, which will take less fluid to hit the "FULL" mark with. A little looser in the lower speed ranges, but should work fine above about 2500rpm. No real need for an aftermarket "higher stall" converter. Just a factory application which will give a little more stall speed with more horsepower in front of it (compared to the OEM application). NOT the first time OEMs have used a six-cylinder-spec converter behind a strong V-8 for a higher stall speed.

Just some thoughts,
CBODY67
 
I was actually thinking of knocking the weights off to see if the vibration stops. will try this before yanking the transmission out.
in the likely chance ill have to pull the unit, what sites offer good quality t/c?
 
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I was actually thinking of knocking the weights off to see if the vibration stops. likely will try this before yanking the transmission out.

The weights are spot welded on so they can be knocked off, just be careful you do not damage the convertor housing in the process. You can try driving the car that way. You have camshaft that is designed for operation over 2000RPMs pushing a heavy C-Body so you are probably going to have issues getting it to move "out of the hole"; but it won't hurt anything try it and see.

Dave
 
Seems like one of the MP Race Manuals mentions using a "hammer and chisel" to knock the weights off. Of that bothers you , then a grinder used carefully AND in an environment where the resulting sparks would NOT cause a fire to start.

It should be noted that "stall speeds" are a variable thing. The more power in front of the converter, the higher the stall speed. Before the hot rod converter trans people got into the torque converter business, other than for full-race transmissions, it was common to use smaller diameter OEM converters to get the desired higher stall speeds. Even if it seemed totally out of whack. Like a 8" torque converter from a German Opel application in a GM automatic.

In my '78 Chrysler service manual, stall speeds are openly listed. Some that went close to 3000rpm with the 440HO motors. Of course, those cars would have 3.21 gears and such, too.

Back in the '80s, GM and Chrysler did some "factory warehouse sales" to the dealers. I got a new THM350 ('81 Z/28 or Corvette application) for my '77 Camaro. I'd know that all of the new Z/28s prior to that all would spin the rear wheels (against the foot brake) by 1800rpm AND that it came with a V-6 converter in it. When I put it in my Camaro with a 2.56 rear axle, it took some getting used to driving it on the highway, lest cruise fuel economy take a hit. With the particular gear ratio and tire size, 2000rpm was about 62mph, which apparently was just under when the torque converter was considered "locked-up" hydraulically, with the least amount of slippage in the converter. I never did hook up the electric converter clutch, though.

Try the car and see how it leaves the line at 3/4 throttle, using WOT about 40' from launch. This will do a few things. It will keep the intake manifold vacuum a little higher so the vacuum advance is still in play in ignition timing, before the centrifugal advance really starts to happen. More torque, as a result. Then, once the car is moving and initial acceleration happens AND before the 1-2 shift, let it run out with WOT. WOT from idle can be disappointing, as the motor will probably lug a bit as it seeks to climb out of the lower rpm "hole" when centrifugal timing advance starts to happen. Less initial throttle, against the brake even, will let more advance in the motor with the vacuum advance, instead.

The looser converter would let the engine leave at a higher rpm level, when more basic power is available, in comparison, BUT a looser converter can have the things to get used to I mentioned above.

The KEY thing is to learn how to drive the car so it responds the best for the combination you have. LEARN to use less initial throttle rather than WOT right off of idle or when staging the car "against the brake". Many people desire to "just floor it" and hope that "a big show" happens. Some can get away with that, but if your vehicle can't, don't try to force it to do something it's current equipment combination is not really oriented to do (wilder cam, tighter converter). The sooner it gets into the 2500rpm level, the better, even if less tire "noise" results.

I suspect the cam you have is a bit stronger than the old 383 Road Runner cam, so using a reman torque converter for that OEM application would be reasonable. Which would be the same cam in the 440 GTX applications, too. Which would leave the reamar axle ratio being the only other real factor involved. Personally, I like "passing gear performance" better than "stop light grand prix" performance. Especially getting that 3-1 downshift that puts the engine rpm above 3000rpm in low gear!

How much fluid does it take when you do a drain/refill ATF change? The smal, ler converter takes about 16 qts rather than 17, as I found out with my '70 Monaco 383 "N" car. With the 3.23 gear, throttle response really got "tight" at 62mph, which was probably the result of the smaller diameter converter. Might be that you already have the smaller converter?

Enjoy!
CBODY67
 
I ended up replacing the t/c for one out of a 69 charger, a 10" converter, neutral balanced. Replaced the flex plate for a solid one from 440 source. Started the car up today and it runs smooth as glass. I have a few more things to finish up on this car before its first drive in more than 30 years.
 
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