balanced 340

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D.Coulter

D.Coulter

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hey guys, question: I have a balanced 71 340 but I was thinking of replacing the fact. harmonic balancer with this unit. will it work or will I need additional work ? nothing visually wrong with the fact. unit other then it being old. I am thinking it may be a small piece over looked and I need to deal with it. The price is good for this unit.
pro-race-products-pro-street-harmonic-balancer-68.jpg

Fits: SB-Chrysler 318-360

External Balance

7.30" Diameter

9.36 LBS.

PRO/STREET dampers are not intended for racing, the fact that they are cast of nodular iron, as opposed to ordinary gray iron, means that they are suitable for higher rpms than most competitive models. (Note: The PRO/STREET Nodular Iron Harmonic Dampers are NOT SFI certified). However to prove the integrity of the PRO/STREET dampers, Pro Race Products had the SFI test lab run some spin tests. The PRO/STREET damper was subjected to 8,000rpm for one hour, and then 12,500rpm for 15 minutes with no sign of degradation! Unlike many OE dampers, or other replacement style dampers, the PRO/STREET range feature a bonded elastomer! The elastomer is injected at high temperature and under extreme pressure. In fact during the manufacturing process EACH AND EVERY PRO/STREET damper is subjected to elastomer bond test of 3000lbs separation force. If there is any sign of bond degradation then the damper is scrapped. Many OEM dampers aren't bonded at all.

Key Features:

Nodular Iron Construction - Most cast dampers are manufactured from gray iron castings. Nodular iron is over 30% stronger than gray iron.

Bonded Elastomer - Outer ring and inner hub are bonded (vulcanized) to the elastomer. This minimizes the potential for the outer ring to move on the hub, losing true TDC position.

Removable Counterweights - Externally balanced models feature bolt-in counterweights, making it easy to switch from an externally balanced engine to an internally balanced engine.

Precision Balanced - Dampers are machined and precision balanced.

60° of permanent easy to read timing marks (40° on SB Ford models)
 
I’ve got that on my 273 commando. Works good.

Jake
 
It may throw your crank pulley off. The factory balancer has an indentation in it where that one does not.
 
I put one the one for internally balanced 340s on my internally balanced 340. But haven't fired it up yet. I believe it'll be fine.

Pat
 
For a '71 340, you need the internal balance version. The external balance version may have bolt-on weights that may be removable to make it an internal balance damper, but just be aware that you can get one that is ID'd as internal balance.

Dale Coulter said:
Bonded Elastomer - Outer ring and inner hub are bonded (vulcanized) to the elastomer. Precision Balanced - Dampers are machined and precision balanced.
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Let us hope the rubber is indeed vulcanized or it will just be goo! And that it is precision balanced....marketing..... sigh.
 
It depends on how the balance job was done.

If the guy who did it made corrections on the damper than it will change the balance. Also, you are making the assumption that the OE damper was zero balance, the new damper is zero balance and no corrections were made on the OE damper.

Way too many assumptions for me.

That said, Chrysler balance jobs were real pretty and I never had an OE balance shake, but I've seen some other balance jobs shake like a dog pooping peach seeds.
 
Isn't your 340 internally balanced? The 360 is externally balanced, I believe. Be careful you don't select the wrong harmonic balancer.
 
yellow rose said:
It depends on how the balance job was done.

If the guy who did it made corrections on the damper than it will change the balance. Also, you are making the assumption that the OE damper was zero balance, the new damper is zero balance and no corrections were made on the OE damper.
Click to expand...

I see your point... but if the 340 in question uses a stock balancer for that year, then IMHO it is a pretty high % probability assumption that the OEM balancer was not touched. The unbalanced damper used in later 340's is pretty obviously imbalanced.

Maybe the OP can help us with a few more details.


General Disarray said:
Isn't your 340 internally balanced? The 360 is externally balanced, I believe. Be careful you don't select the wrong harmonic balancer.
Click to expand...
You are correct for the stock '71 internals.
 
yellow rose said:
It depends on how the balance job was done.

If the guy who did it made corrections on the damper than it will change the balance. Also, you are making the assumption that the OE damper was zero balance, the new damper is zero balance and no corrections were made on the OE damper.

Way too many assumptions for me.

That said, Chrysler balance jobs were real pretty and I never had an OE balance shake, but I've seen some other balance jobs shake like a dog pooping peach seeds.
Click to expand...
there were no corrections made to the OE unit. I did a visual inspection and it appears in good condition I thought I would do an up grade. not sure yet
 
paint it or put lots of clear coat on because they rust easily and don't stay pretty for long .
 
Dale Coulter said:
there were no corrections made to the OE unit. I did a visual inspection and it appears in good condition I thought I would do an up grade. not sure yet
Click to expand...
Check the rubber between the inner and outer rings. Any cracks show that the rubber is hardened up, which would be 99% expected at this age of part. The hardness of the rubber is part of the tuning of the damper to properly damp out a critical frequency range of internal crankshaft vibrations; when it gets hard, it does not do its job well (or maybe even at all).

The damper's job is to damp out high frequency internal vibrations within the crank itself (which have nothing to do with imbalance vibrations). Inadequate damping of these internal vibrations can sometimes lead to premature crank failure. That is the whole point of using one.
 
nm9stheham said:
Check the rubber between the inner and outer rings. Any cracks show that the rubber is hardened up, which would be 99% expected at this age of part. The hardness of the rubber is part of the tuning of the damper to properly damp out a critical frequency range of internal crankshaft vibrations; when it gets hard, it does not do its job well (or maybe even at all).

The damper's job is to damp out high frequency internal vibrations within the crank itself (which have nothing to do with imbalance vibrations). Inadequate damping of these internal vibrations can sometimes lead to premature crank failure. That is the whole point of using one.
Click to expand...
ok thanks for the info. the rubber is cracked and I will be replacing that unit...I have to much money in this thing to over look this often forgotten over looked part. thanks again.
 
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