Harmonic balancer questions

[str12-340]

I think it is possible that the ring around my harmonic balancer has slipped leading to vibration at a certain rpm range.

The engine is an internally balanced 318 cast in 1980 with the original cast crank. I bought the engine with a fresh rebuild including new pistons and balancing, and it has done this from the beginning.

Question 1: Is it correct that all pre Magnum 318s are internally balanced?

Question 2: are the harmonic balancers for these internally balanced engines interchangeable? Are they interchangeable with internally balanced 340 balancers?

Question 3: I have seen info about a company that rebuilds original balancers. If the outer ring has slipped, will they be able to figure out what the orientation is supposed to be?

Question 4: Is there a source for new balancers for these engines? This in a measured 8.5:1 compression engine with 308 heads in a car that is driven. I don't need anything fancy or SFI approved.

Any related advice is welcome.

 

[volaredon]

Yup the rebulders have the capability to realign the outer ring. Unless you can find NOS you're better to have yours rebuilt vs buying a new/chinamade unit.
Damper doctor or damper dudes, I've used them both. 2 different/separate companies.

 

[Vaanth]

I think it is possible that the ring around my harmonic balancer has slipped leading to vibration at a certain rpm range.

The engine is an internally balanced 318 cast in 1980 with the original cast crank. I bought the engine with a fresh rebuild including new pistons and balancing, and it has done this from the beginning.

Question 1: Is it correct that all pre Magnum 318s are internally balanced?

Yes.

Question 2: are the harmonic balancers for these internally balanced engines interchangeable? Are they interchangeable with internally balanced 340 balancers?

Yes, but note that pre-1972 has an asymmetric pulley bolt pattern with one bolt offset. Extending the mis-matched hole in the pulley allows interchange. 340s built after 4/11/1972 are externally balanced.

Question 3: I have seen info about a company that rebuilds original balancers. If the outer ring has slipped, will they be able to figure out what the orientation is supposed to be?

I'm not familiar with the company, but if they build them properly, they should be able to align it properly.

Question 4: Is there a source for new balancers for these engines? This in a measured 8.5:1 compression engine with 308 heads in a car that is driven. I don't need anything fancy or SFI approved.

Dorman makes a new balancer, with the symmetrical bolt pattern: 594-021. Quality is unknown though.

ATP also makes a new balancer, part number 102003. Quality is likely better than Dorman.

Any related advice is welcome.

EDIT: Corrected transposed digits in the Dorman link title.

 

[Professor Fate]

Question 1: Is it correct that all pre Magnum 318s are internally balanced?

All 318s, including Magnum 5.2s, are internally balanced.

Question 2: are the harmonic balancers for these internally balanced engines interchangeable?

Aside from the bolt pattern changing as already mentioned, the timing mark on the balancer changed in 1970 when the marks changed from the passenger side to the driver's side.
The balancers will functionally interchange, if you make accommodations for the timing mark difference (and the bolt pattern).

 

[66fs]

I think it is possible that the ring around my harmonic balancer has slipped leading to vibration at a certain rpm range.

The engine is an internally balanced 318 cast in 1980 with the original cast crank. I bought the engine with a fresh rebuild including new pistons and balancing, and it has done this from the beginning.

Question 1: Is it correct that all pre Magnum 318s are internally balanced?

Question 2: are the harmonic balancers for these internally balanced engines interchangeable? Are they interchangeable with internally balanced 340 balancers?

Question 3: I have seen info about a company that rebuilds original balancers. If the outer ring has slipped, will they be able to figure out what the orientation is supposed to be?

Question 4: Is there a source for new balancers for these engines? This in a measured 8.5:1 compression engine with 308 heads in a car that is driven. I don't need anything fancy or SFI approved.

Any related advice is welcome.

Didn't the use the balancer when the balanced to rotating assy? Makes me wonder if they really balanced to rotating assy. Did you balance the torque convertor, flex plate, or flywheel ,pressure plate? There were differences in internally dampers, but they all should work, pulley bolts and timing marks aside.

 

[Plymouth 65]

Just get a stock replacement for it. It's not a race engine, so it'll be fine. 65

 

[str12-340]

Vaanth - thanks for the speedy and complete information! I have been finding that as I get older relying on memory without confirmation is a mistake . I'll post a question and ask for reviews for those balancers.

 

[Miranthis]

Just get a stock replacement for it. It's not a race engine, so it'll be fine. 65

Where are you getting the stock ones? Just at Advanace/NAPA/ etc.? My 66 273 is going out for rotating assembly balancing and I prefer the original harmonic balancer be replaced, just in case. I'd prefer it to look basically stock, and certainly to have the timing mark in the right place. Searching on line has lots of performance ones, but I just need a "new" stock one.

 

[str12-340]

Did you balance the torque convertor, flex plate,

I put an A500 torqueflite behind the engine and had the converter rebuilt by a reliable supplier of converters when the transmission was rebuilt, the flex plate is the small stock 1970 plate for a 904 and seems too small to have been a significant source of balance. Does that seem appropriate?

Just get a stock replacement for it.

Are you suggesting the Dorman or ATP balancers mentioned in post #3?

More information:

The engine was built by a meticulous builder and he supplied me with all the details of weights etc, from the balancing so it doesn't seem likely that balancing was not done, but of course anyone can make a mistake. They used the balancer that was on the motor (1980 - 45 years old) and I was thinking that the ring could have slipped when the engine was run in or when I fired it after installation.

I tried everything beyond the engine - the vibration is not tied to the speed of the vehicle, but rather the rpm of the engine, so that eliminated the driveshaft, rear end, driveshaft angles (which were measured and adjusted during installation). I figured that replacing the balancer was the easiest next step rather than pulling the engine/transmission.

 

[Plymouth 65]

Yes, the Dorman or ATP dampers are probably the closest to the stock damper. 65

 

[str12-340]

Correct Dorman number 594-021. The number listed in Post #3 has 2 numbers transposed (it's for a Toyota

 

[Vaanth]

Correct Dorman number 594-021. The number listed in Post #3 has 2 numbers transposed (it's for a Toyota

Thanks for spotting that. I edited the post to correct it. The link was correct, but the title had the transposed numbers.

 

[66fs]

I put an A500 torqueflite behind the engine and had the converter rebuilt by a reliable supplier of converters when the transmission was rebuilt, the flex plate is the small stock 1970 plate for a 904 and seems too small to have been a significant source of balance. Does that seem appropriate?


Are you suggesting the Dorman or ATP balancers mentioned in post #3?

More information:

The engine was built by a meticulous builder and he supplied me with all the details of weights etc, from the balancing so it doesn't seem likely that balancing was not done, but of course anyone can make a mistake. They used the balancer that was on the motor (1980 - 45 years old) and I was thinking that the ring could have slipped when the engine was run in or when I fired it after installation.

I tried everything beyond the engine - the vibration is not tied to the speed of the vehicle, but rather the rpm of the engine, so that eliminated the driveshaft, rear end, driveshaft angles (which were measured and adjusted during installation). I figured that replacing the balancer was the easiest next step rather than pulling the engine/transmission.

I would think the torque convertor might be suspect? Not sure. I balance everything and my engines are very smooth. I do have an extra late 318 Damper you can have for shipping, not pristine but it worked well. I'm tired of tripping over it. You could try it and send yours off to be rebuilt. They repot the elastomer and balance it. I like the original stuff. BHJ has a damper with the timing marks for early Chrysler small blocks with the timing marks in the right place, but I can't remember if it has the offset pulley threaded hole. They do not list it on their website but if you call they will make one for you.

 

[str12-340]

BHJ?

 

[junkyardhero]

BHJ?

Small Block V8 : HarmonicDampers.com by BHJ Dynamics, Performance Harmonic Dampers, Harmonic Balancers and Specialty Crankshaft Vibration Dampers

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harmonicdampers.com

 

[66fs]

Does it vibrate in neutral or while driving?

 

[abodyjoe]

i used one of these. nice piece.. price has gone up from what i think i paid.. Harmonic Balancer - Chrysler Compatible - 273, 318, 340, 360 and 408

 

[gzig5]

Didn't the use the balancer when the balanced to rotating assy? Makes me wonder if they really balanced to rotating assy. Did you balance the torque convertor, flex plate, or flywheel ,pressure plate?

I've been told by a well respected builder that posts here, that he will not include the external accessories like the balancer, flex plate, or flywheel when balancing a rotating assembly. Each of those items are/should be balanced during manufacturing and should be built to a spec that is conducive to a smooth running engine. For a performance engine, he doesn't want to have something built into the rotating system that could be changed out and then throws the system out of balance, rather than being able to simply replace/fix the faulty part. You want to have to tear the engine apart for balancing if you put a new flywheel on and the base system is not as well balanced anymore without the old one? Maybe a hard view of it, but I get his point. But like most things, I'm sure it has been done both ways thousands of times successfully.

 

[66fs]

I've been told by a well respected builder that posts here, that he will not include the external accessories like the balancer, flex plate, or flywheel when balancing a rotating assembly. Each of those items are/should be balanced during manufacturing and should be built to a spec that is conducive to a smooth running engine. For a performance engine, he doesn't want to have something built into the rotating system that could be changed out and then throws the system out of balance, rather than being able to simply replace/fix the faulty part. You want to have to tear the engine apart for balancing if you put a new flywheel on and the base system is not as well balanced anymore without the old one? Maybe a hard view of it, but I get his point. But like most things, I'm sure it has been done both ways thousands of times successfully.

I don't leave anything to chance. I do have flywheels balanced separately then pressure plate on the balanced flywheel, very eye opening. In my opinion, it is fine to balance the rotating Assy, but you better check the damper to make sure it doesn't throw anything off. Nothing like taking the time and money to balance your engine and to have a vibration. I also balance drive shaft and brake rotors.