Balancing a 360 internally

[efriedrich]

The machinist at the local speed shop says that by using a lighter piston and rod and with a new vibration dampener that he can balance the stock crank of my 88 360 internally. Is this true or even common, I am just getting started with this motor and want to reuse as many of the original parts to keep costs down while picking up as much HP as possible.

 

[1968FormulaS340]

You posted 3 goals:

1. reuse as many of the original parts as I can

2. keep costs down

3. up as much HP as possible


The machinist recommended a switch from external balancing to internal.

His goal:

Milk you for every dime you have.


Just my opinion.

 

[skrews]

Don't let that guy blow smoke up your ***. Not gonna happen with a stock crank, without a lot of Mallory metal. If you want internal balance, get an aftermarket crank. Better off leaving it ext. balanced and taking the money you saved and putting it somewhere else like the heads.

 

[Lonewolf3165]

Yeah, internal balancing isn't quite that simple. You need to add heavy & expensive mallory metal to the crank & figure additional time costs associated with it. Better alternative now is replacing the crank with an internally balanced aftermarket one. But if this is a low budget build & you aren't making radical changes, keep the bottom end stock & use the money where it will make more power per $ for you. Cam, intake, heads...

 

[Johnny Mac]

it's extremely common on race engines that will see large amounts of RPM. personally i paid about $300 to have mine balanced. I run a trickflow neutral balance balancer, and needed a flywheel for internal balance. but i make 650 HP and turn 7300 RPM...long story short, if you're reusing a stock crank, just throwing some pistons in it to bump compression and add a few ponies...stick with external. You won't see enough benefit from the switchover to make it worth doing.

 

[efriedrich]

So if I reuse the stock crank and rods and use something like a kb107 piston should I still have it balanced.

 

[CultClassik]

Always!

 

[sireland67]

So if I reuse the stock crank and rods and use something like a kb107 piston should I still have it balanced.

Yes the pistons are different weights.

When I put KB 107 in my 94 magnum with stock rods and crank (reworked)
The crank need mallory added to the bottom end.
The balance only run $250 and I kept it external.

I would recommend balancing if there is a 10 gram difference on piston weight if using stock crank, and rods.

 

[70aarcuda]

I have a 360s with lite ross pistons, 80 gram pins and scat i beam lite weight rods...and it would still not balance internally without mallory metal...so it is externally balanced..

 

[moper]

I always balanc internally. The cost is not huge - Normally around $200 for Mallory. The additional power and life is well worth that couple hundred bucks, and it's something that you will feel (or not feel...lol) every time the engine is run.