Balancing Engine

[John Keigley]

I'm putting together my first Mopar engine. It's a 360 with some mods that will be street driven. Is balancing vital? Thanks

 

[1970Duster]

Yeah

 

[71Scamper]

think about thousands of pounds of force trying to rip apart the bottom end! That's what it's like when it's out of balance. You'll also have horrible vibrations that will rattle your teeth out of your head.

 

[Robbie2734]

Are you re-using the old rotating assembly? If you are just doing bearings, rings and using the old pistons and rods in a daily driver I would think it will be ok. Keep the rods and pistons on the journal they came from and don't spin it over 8 grand..LOL

 

[John Keigley]

I replaced the pistons and the rods. I will get it balenced. Thanks.

 

[Lelo Dart]

New pistons and the motor needs a balance even if stock type pistons. If your doing any mods and looking for performance then it should be balanced.

 

[Bad Sport]

I replaced the pistons and the rods. I will get it balanced. Thanks.

Yep, you need to get it balanced for sure. I'm replacing just the pistons in my build, and I will be balancing the rotating assembly.

 

[Locomotion]

I assume you're using the OEM balancer up front?

What's out back - converter with proper 360 weights welded on or a B&M flexplate for the early/original 360 external balance?

I was never sure how they balance a 360 rotating assembly if using a converter with the welded on weights. Does it get bolted on? I always used a B&M flexplate or internally balanced my 360's.

 

[DaveBonds]

You should be within the usable range on a relatively stock piston replacement, if you number the rods and caps, but if you replace any other components, you might consider it.

Be sure to check the stock balancer against true/ corrected TDC. Mark the balancer with masking tape and a pen, at .060" drop of the piston, before TDC, then again after TDC. Use a dial indicator on the block with a magnetic base. Then measure the distance between your marks, and find/ mark center. Rotate the crank back past it and come up to that mark in the correct rotational direction. That is true TDC. A lot of the balancers slip.

 

[71Scamper]

You should be within the usable range on a relatively stock piston replacement, if you number the rods and caps, but if you replace any other components, you might consider it.

Be sure to check the stock balancer against true/ corrected TDC. Mark the balancer with masking tape and a pen, at .060" drop of the piston, before TDC, then again after TDC. Use a dial indicator on the block with a magnetic base. Then measure the distance between your marks, and find/ mark center. Rotate the crank back past it and come up to that mark in the correct rotational direction. That is true TDC. A lot of the balancers slip.

A great reason not to cheap out on a good brand name balancer!

If you reuse the rods but replace the pistons, and the pistons weight the same, there's no need to balance. If you replace the rods, then you need to re-balance, even if the rods weigh the same because the ratio of weight between the big end and small end may be different from your old rods.

 

[nerd racing]

Make sure they have your Crank damper with the counterweight and your weighted flex plate/flywheel if you are staying external balance. Now would be a good time to upgrade to a new damper. If you plan on drag racing an SFI 18.1 Spec certified one would be the ticket.