4.3 Vortec Harmonic Balancers...

[lintmann]

I'll try and make this short and too the point to keep things simple.

I have a 98 4.3 with a cracked block and I just bought a 99 4.3 from what I was told came from an S10. I can't use the crankshaft from the cracked block because of water damage to it. The crankshaft from the S10 looks nice so I would like to use it. Now the crankshafts are slightly different but the harmonic balancers are very different. The S10 one is much lighter, smaller and has a recessed area for the pulley compared to the original one from the boat which is similar to an old early small block style.

My question is, do you think it would be okay to use the original marine one in place of the lighter S10 one or do I need to keep the balancer with it's crankshaft?

Thanks.

 

[Bondo]

Ayuh,..... When swapping long blocks, it's best to keep 'em as original as possible,.....
No way I'd swap the crankshafts, without a trip to the machine shop,.....
I'd be leary of swapping the balancers, as the crank, flywheel, 'n all is balanced as an assembly,.....

 

[Scott Danforth]

the 1998 should be identical to the 1999 as far as crank/rods/block go.

the automotive dampers are generally smaller because the motor doesnt spend the amount of time at WOT in a truck that it does in a boat.

With that stated, use the 1999 short block as is. get a new marine water pump, new marine head gaskets, new brass core plugs, bolt the 1999 heads back on. bolt on the heavier damper and all the marine accessories

 

[lintmann]

Thanks guys for your quick replys.

My initial thoughts for using the original marine internal components was that they would have much less wear and tear than the truck engine because it would likely have had a lot fewer rotations on it in its lifetime. The marine engine had practically no varnish inside so it was way cleaner than the truck engine but now that I have the truck engine apart, I see that it has very minimal wear too. Actually its about the same as the marine engine so yes, i will be using all of the S10 internals that belong in this block.

I realize that when an engine is originally assembled that the rotating components are balanced. Sometimes the harmonic balancer and flywheel are balanced with the internals and sometimes not. I've read yes and no so I don't really know what to believe with this 4.3. I do know that if a balancer or flywheel has to be replaced in service that it doesn't require a rebalance of the whole internals so for the most part replacing a harmonic balancer shouldn't be a big deal. I was just concerned about the extra mass of the marine balancer compared to the original S10 one.

Thanks again guy, much appreciated!

 

[Jmunk]

The harmonic balancer is neutral balanced and can be changed with no consequences.

 

[nola mike]

Thanks guys for your quick replys.

My initial thoughts for using the original marine internal components was that they would have much less wear and tear than the truck engine because it would likely have had a lot fewer rotations on it in its lifetime. The marine engine had practically no varnish inside so it was way cleaner than the truck engine but now that I have the truck engine apart, I see that it has very minimal wear too. Actually its about the same as the marine engine so yes, i will be using all of the S10 internals that belong in this block.

I realize that when an engine is originally assembled that the rotating components are balanced. Sometimes the harmonic balancer and flywheel are balanced with the internals and sometimes not. I've read yes and no so I don't really know what to believe with this 4.3. I do know that if a balancer or flywheel has to be replaced in service that it doesn't require a rebalance of the whole internals so for the most part replacing a harmonic balancer shouldn't be a big deal. I was just concerned about the extra mass of the marine balancer compared to the original S10 one.

Thanks again guy, much appreciated!

Either balancer will be fine. I'd take a used auto motor over a marine any day. Marine engines are driven much harder than auto, and that doesn't even count the (usual) open cooling corrosion and generally harder environment/op conditions

 

[stresspoint]

The harmonic balancer is neutral balanced and can be changed with no consequences.

agreed, however , i like to replace with a new balancer when doing motors.

most would ask ?why do this, >> ,A, my machinist balances the rotating assembly's on all ""my""" motors , over kill i know ,but hey i have a 500 horse Vortec that is now 4 years old in a boat and it still runs like scalded dog.
we did an experiment and stuck a used balancer from a random motor on a rotating assembly , "it sent the screen crazy" , stuck a new one on the same assembly and it was only slightly out.
so with that info , i always spring for a new balancer.

FWIW ,and this is what got me , there is no part number change as far as i could see, i the non vortec balancer could different than that of a Vortec that is the only differences that may need to be taken into consideration when replacing chev SB balancers.
its easy to notice the difference the robber flies apart @5000 rpm.
i also believe the TDC mark is in a different location on the wheel.

 

[lintmann]

Thanks for your thought too, I'll stay with the marine one for this stock rebuild.

 

[vroom ZOOM]

I'm pretty sure only the crank is balanced on those motors. Having the crank, balancer, flywheel pistons, and rods all balanced together is really only for the high end motors. If the cranks look the same, get a new marine balancer and throw it together. I wouldn't use the old balancers, 4.3s (or any motor) can crack a crank if the balancer goes bad.

I will also add that if you are in salt water, you can take this opportunity to go closed loop cooling (you can then keep the truck head gaskets and water pump) and you won't be able to go closed loop later.