Harmonic balancer

[Firedome8]

Lately I have been seeing SBC dirt track cars with fresh rebuilds for the new season with no harmonic balancers. When I ask about it the common answer is the builder says that it is not needed because the assembly is balanced together. The engines are basically stock 500 2 barrell hei ignition reveing to approximately 7000 rpm with hydraulic flat tappit cam. I see the timming mark jittering at full throttle 3 to 4* . My question is should I question this practice or is it a non issue. Thanks for any responses.

[Walter R. Malik]

Lately I have been seeing SBC dirt track cars with fresh rebuilds for the new season with no harmonic balancers. When I ask about it the common answer is the builder says that it is not needed because the assembly is balanced together. The engines are basically stock 500 2 barrell hei ignition reveing to approximately 7000 rpm with hydraulic flat tappit cam. I see the timming mark jittering at full throttle 3 to 4* . My question is should I question this practice or is it a non issue. Thanks for any responses.

The car will probably accelerate a tiny bit faster with less rotating weight on the crankshaft. Personally, it is not a good practice to run no harmonic damper at all; to me, a couple hundredths is not worth a potential engine mess.

[Ken_Parkman]

A "harmonic balancer" is actually a torsional vibration damper which is intended to prevent internal crank twisting deflections (due to piston pulses) from getting out of control and failing the crank due to fatigue. It is so deep many aftermarket damper manufacturers have no clue. It is a very complex subject where when the piston exciting orders line up with one of the crankshaft natural frequencies extremely destructive deflections and fatigue loads can develop. I'm talking crazy fatigue stresses and it's a matter of when not if it breaks.

Often for convenience the damper is used for adding weight to externally balance the reciprocating assembly. It's convenience cause it's there, not the main function of the damper.

Balance and damping are not related.

To me running an engine without a damper is a disaster waiting to blow up. You may get away with it in isolated cases where you are operating in some narrow rpm range where the exiting orders and frequencies do not line up, but unless you know it is a crapshoot. If the timing chain is getting beaten up it is a sign there is a serious torsional vibration problem.

[fabr]

That 3-4 degree jitter tells the story,lMO . The engine should have a damper.

[Mark O'Neal]

I'm good with no damper. So are all of the bearing manufacturers.

.....but I sell parts every day. I also love nitrous with no tune.....so don't listen to me.

Balancing has nothing to do with harmonics. If it did, you could run the proper balancer and have no need to balance the rotating assembly.

[Tom Walker]

Are these engines running some kind of accessories or pumps off the snout of the crank or cam?
I ask, because some have stated that certain applications get by without a crankshaft damper because the accessories or pumps offer some damping abilities.
Not saying I agree, but there are some that say this is how they are able to run without a damper, personally, I like what a damper offers.

[lefty o]

its not the best idea, unless you are the engine builder who likes to guarantee repeat business.

[Firedome8]

Thanks everyone for your responses. I do not build engines so I do not want to contradict their engine builder. I wanted to pose the question for my own sake. If the engine is truly balanced with the hub on the crank can you just put a random sbc harmonic balancer on it ?

[ClassAct]

Thanks everyone for your responses. I do not build engines so I do not want to contradict their engine builder. I wanted to pose the question for my own sake. If the engine is truly balanced with the hub on the crank can you just put a random sbc harmonic balancer on it ?

No. They are not balancers. They are dampers. There is zero excuse to not use a damper.

[RDY4WAR]

Are these engines running some kind of accessories or pumps off the snout of the crank or cam?
I ask, because some have stated that certain applications get by without a crankshaft damper because the accessories or pumps offer some damping abilities.
Not saying I agree, but there are some that say this is how they are able to run without a damper, personally, I like what a damper offers.

Sprint engines run the oil pump right off the camshaft snout. I had a discussion with Billy Godbold a while back about that, talking about his experience with one on the spintron. When I asked about the effectiveness of the oil pump acting as a damper, he said "you couldn't design a better one."

[RCJ]

Some restricted motors don't make enough power to stress parts. Same reason people get by with Walmart oil

[Mark O'Neal]

Are these engines running some kind of accessories or pumps off the snout of the crank or cam?
I ask, because some have stated that certain applications get by without a crankshaft damper because the accessories or pumps offer some damping abilities.
Not saying I agree, but there are some that say this is how they are able to run without a damper, personally, I like what a damper offers.

Sprint engines run the oil pump right off the camshaft snout. I had a discussion with Billy Godbold a while back about that, talking about his experience with one on the spintron. When I asked about the effectiveness of the oil pump acting as a damper, he said "you couldn't design a better one."

I'll buy that. Anything with a belt.......

[englertracing]

Are these engines running some kind of accessories or pumps off the snout of the crank or cam?
I ask, because some have stated that certain applications get by without a crankshaft damper because the accessories or pumps offer some damping abilities.
Not saying I agree, but there are some that say this is how they are able to run without a damper, personally, I like what a damper offers.

Sprint engines run the oil pump right off the camshaft snout. I had a discussion with Billy Godbold a while back about that, talking about his experience with one on the spintron. When I asked about the effectiveness of the oil pump acting as a damper, he said "you couldn't design a better one."

Well,
They run the oil pump off the front, and the power steering and fuel pump from the rear. In conversation with someone else with a spintron the oil pump scavenge stages pull random slugs of liquid and air, which isn't super bitchn.
They run the water pump off of the front of the crank..... doesn't make up for the harmonic balancer .......
I've heard what makes it "ok" in circle applications is that the rpm is never constant.

[stealth]

Do top tier teams run without one?

I'm sure if NASCAR teams could find any advantage they would have left the balancer off long ago. These teams can afford to trash all the parts after one race if it netted any type of advantage.

[amc fan]

Do Pro Stock,Top Fuel,and some of the other classes use Harmonic balancers.