Technical Harmonic balancer

Anyone know if a 327 swp balancer can be used on a later 350 or will it mess up the harmonics of the engine? Thanks

 

The balance is the same. But the damping effect of the smaller 327 damper isn't quite up to the task of the longer stroke 350 crank, so it might not be the best thing to use. It'll fit and run ok, the engine just might not last as long.

 

You...DON'T...have a balancer !!!
You have a harmonic "damper".
That ring on the front of your engine does...no...balancing. Under normal circumstances, that ring is "neutrally balanced when your, assembly is balanced.

IF, you had a externally balanced, 400 chevy, or an externally balanced 454, or another "externally"...balanced engine, THEN, you'd have a "harmonic balancer".

The answer to your question has been previously answered.

Mike

 

Semantics.........

 

Is is this a single piece of rear main or a 2 piece

 

The rear seal type doesn't seem to affect which damper is used on the 350. It does affect which flex plate or flywheel is used.

 

Not sure what "swp" means, did you mean "SHP" which is special high performance.
Also, define "later".......to my knowledge the 1967 350 used the same (style) weld-on timing tab and keyway location on the damper as the pre 1969 327's (and 302's), the later engines used a bolt on timing tab, with the damper keyway broached (about) 8 deg's off.
Besides, how would one know if their engines' harmonics were in question?

 

I think swp means short water pump.

The dampers are the same for short or long pump, the pulleys are different. The dampers are different for different stroke engines

 

The dampers are not the same. Timing marks in a different place to clear the water pump with the timing light.

 

Its always best to use the correct harmonic balancer for the motor. Unless anyone has taken measurements on a different application there is no way of knowing if it works.

I ecpect the 350 has a much larger inertia ring and longer rubber section as its dealing with more resonant energy.

 

One piece

 

Was just wondering about going to short water pump for clearance?

 

Thank you and excuse me.

 

Use a short water pump and ignore the damper (keep the 350 damper on the engine).

Chevy used the short water pump and the 350 engine in trucks through 1972, and Corvettes starting in 1969

 

Go ahead and call it harmonic balancer if you want to, most people do, and we all know what you're talking about. Most people call the little pedal on the right a gas pedal, even if they drive a diesel or (heaven forbid) an electric car.
When I was younger and I tried to correct my Daddy on what things were supposed to be called, he would tell me
"Everybody likes a little ass, but nobody likes a smartass" Good Luck

 

I don't like to correct people using the wrong term most of the time...but I try to use the right term when I can.

I think most folks don't understand what a harmonic damper does, so the words are kind of meaningless, they just call it what they hear it called.

 

Mike, I guess it depends on where you reside, here in the Sunny South we have always referred to it as a harmonic balancer. HRP

 

But it doesn't balance anything, it just dampens the torsional vibrations in the crankshaft.

Sometimes the names of parts that were designed by engineers mean something to engineers, but not the rest of the world. This is one of those cases. It can drive engineers nuts.

 

The balancer for a one piece rear main 350 is different from a early 2 piece. When I built my 1990 350 SBC I tried to use a earlier balancer I had, but it wouldn't even begin to go on the crank snout.
I was told these 1 piece main seal 350's are balanced differently than early 2 piece also.
There certainly are "dampeners" that balance also on engines that are externally balanced.

 

Not strictly true. Its both a balancer and a damper. A balancer in the general understanding of the term counter phases an out of balance force to cancel it out. A harmonic balancer the clue is in the name. the rubber element has a resonance frequency that counter phases the resonance frequency of the crank by 180 degrees cancelling it out. the damper part comes from the fact the rubber has a very high damping characteristic so any residual resonant harmonics are also reduced (flattening out the resonance curve).

I used to do this stuff for a living!

 

So , Does the round thing on the front of a 2- piece rear seal 400 ci SBC that has a weight on it balance anything or is the weight just there for the fun of it , how about other engines that are externally " balanced" & use weighted round things ?

 

When I built my 1990 SBC 350 I mixed different generation parts where I could. My top end is all 1st generation style heads, intake, and distributor. I had a nice finned aluminum oil pan I wanted to use but the pans for later 1 piece main seal motors are completely different. Timing sets are also different for the roller cams, so couldn't use a brand new 1st gen set I had. My engine was still machined for mechanical fuel pump surprisingly, so added the pushrod, plate and mechanical pump easily. Flywheel had to be a new style. I got a new timing cover and balancer for the later SBC also.

 

Weird, I didn't have that issue on a couple 87 engines I had (1 piece rear seal). The crank is balanced differently at the back, because there is no flange to add the extra weight that the earlier design has, so they added weight to the flexplate. But they didn't change the front end, that I'm aware of.I looked up the replacement damper for 1980s one piece and two piece engines, they have the same crank bore diameter, but the timing notch is in a different place, as they used different timing tabs depending on accessory drives, which were going through a lot of change at the same time.

I understand that...but the primary function of the part, the reason it exists, is to dampen the harmonics, isn't it? So it seems to me that in the strict semantic sense, it should be called a damper.

I don't mind folks calling it a harmonic balancer...it puts less of a damper on the discussion...

 

if it were a viscous damper the that would be true. Harmonic damper, harmonic balancer, damper pulley and crankshaft damper ( in Europe) are all accepted terms in the industry.

Automotive terms can be a bit confusing, especially accross different countries.

 

I have a Fluidampr on my motor; but they refer to an OEM as balancers:
https://fluidampr.com/troubleshooting-harmonic-balancers/

 

He said "motor"!!!

 

Do a search for harmonic balancer or harmonic dampener and the same results come up. But go to any of the big online auto parts sellers and they still list and describe them as harmonic balancers.
This is one of those things that's just not worth making a big deal about, or correcting anyone about.

 

Bickering about this shit is "traditional"...

 

I'd look at getting one of those "viscous dampeners". There are several brands on the market that are WAY LESS expensive than the name brands and do a good job. I'm converting one to work on a 500 Cad.

Think about this.....If you have an old harmonic damper, the rubber has probably hardened and dry rotting and it may fail. They are designed to dampen harmonics at only one rpm range and with factory designed components. If your engine is using different pistons,rings,cam,rods,compression,flywheel, then the harmonics may not occur at the same rpm or may be greater/lesser than the factory parts create. If you use a viscous damper, it will adjust its damping throughout the rpm range instead of just one range. www.speedmaster79.com/engines-components/harmonic-balancers

 

I used to have a dampener on my engine, but had to keep wiping the liquid off everything. I run a damper now.