[ChevroletSS]

Hey guys my buddy just got a SBC and its bored 60 over I think it was but he only has a stock balancer. At Idel it sometimes starts to vibrate/shake and I told him thats what I thought it was. What could go wrong with something like this??? Its not horrible but it doesnt look right and it doesnt do it non stop. Do you all think thats what it is.

Thanks

[painted jester]

Is the engine vibrating and shaking ? and the harmonic balancer wobbling? but the Balancer doesn't wobble all the time? Or the engine doesn't shake all the time? If there is any wobble to the balancer change it!!!! If the engine doesn't vibrate all the time I doubt if its the balancer. You don't need to change a balancer because an engine is bored.

Jester

[hcompton]

Check the spark plug wires first. Move on to the plugs and all the other stuff first. Distributer Modual and coil are often causes of on again off agin issues.

[Greg T]

Probably have a cylinder or two dropping out.

[ap72]

Has it done this since it was rebuilt? If he didn't have it rebalanced with the new pistons then it's probably from that. Good news is that it really won't hurt anything, bad news is that you need to pull the entire engine apart and balance it if you want to get rid of the vibration.

It could also be from a bad balancer as noted- but a new balancer won't fix a crank imbalance.

[ChevroletSS]

I drove it last night and it did have a slight miss so I told him I would check the plug wires out in the morning. My initial thought was since the engine was bored that the stock balancer wasn the right one to make up for the weight change in the assembly. The balancer does not shake at all. It spins perfectly. The engine will look fine one min and start shaking the next. After I drove it last night Im thinking it needs some plugs and wires but I will check it out first before I start tellin him that he needs to buy parts.

Thanks for the help.

[bondo]

Originally Posted by ChevroletSS

I drove it last night and it did have a slight miss so I told him I would check the plug wires out in the morning. My initial thought was since the engine was bored that the stock balancer wasn the right one to make up for the weight change in the assembly. The balancer does not shake at all. It spins perfectly. The engine will look fine one min and start shaking the next. After I drove it last night Im thinking it needs some plugs and wires but I will check it out first before I start tellin him that he needs to buy parts.

Thanks for the help.

Ayuh,... It don't work that way,...

The balancer isn't necessarily changed when an over-bore is done,...

Generally, the balancer always stays the same, when borin' a motor...