318 to 360 balance questions

[elsensei]

Hi guys-

I don't post here much, obviously, I tend to read more than I write since there's a lot I don't know.

Here's my situation.

I have a 68 charger that was an original 318 904 car. I converted it to a 5 speed with one of keisler's kits, changed out the cam and heads, converted it to fuel injection with a Megasquirt box and hung two ball bearing turbochargers off it. Last time I put it on the dyno it was making 509 RWHP. Way more power than the car can put to the ground.

That motor also had 76000 miles on it. Just a couple weeks ago I came across a complete 360 from an auto trans 1976 RV with 21,000 miles for 500 bucks so I bought it to swap into the charger.

I'm a good way through moving parts from the 318 to the 360 and hope to have it finished within a couple weeks. I'm doing assembly now.

My questions all deal with balancing and the correct parts to use.

1. I read that the 318s were internally balanced, and the 360s externally balanced. The first photo is of the cast crankshaft in the 360 (the 318 was cast also, though I heard those were all forged from the factory.)

Anyway, note the holes drilled in the counterweights of the 360 crank. My question is, is that normal? Meaning, is this somehow a balanced rotating assembly and therefore I can use a neutral balance damper and flywheel or is this a normal 360 crankshaft, externally balanced and therefore I have to use a 360 specific damper and flywheel?

2. Assuming its a normal, external balance 360, see picture 2. This is the harmonic balancer from the 318 and the stock piece from the 360. I assume I should just bolt the stock 360 balancer back on for final assembly?

3. The final question: the flywheel. The third photo is the neutral balance unit that came with the Keisler kit that I then removed from the 318. From my research it appears that a 318 flywheel needs to have a certain amount of material removed from specific spots to make it balance out the 360 rotating assembly.

I laid it all out on Google Sketchup, printed a template, located it exactly on the flywheel and got out a punch and hammer.

As you can see, I center punched three places where the point of a 1-13/64 bit needs to remove .66 inches of material to make this into a 360 correct flywheel.

Of course, I couldn't find a machine shop with that size bit so I bought one online and I'll just drill it myself on a press.

So my final question kind of ties everything together. I need to know before I drill this flywheel if that's what I'm supposed to do, given all my other questions.

Your advice is greatly appreciated.

Sam

[elsensei]

the pics. what a PITA this simple machines forum software is. good god...

[Cooter]

Might wanna drill the other side. Looks like you are on the clutch side in pics.
I don't like doing it this way, but would interested in your results.

[elsensei]

No, it's turned the correct way. That is the engine side.

[Cooter]

Ok...looks to be a new flywheel then..why didn't you just order correct balance?

[elsensei]

No, that's the used flywheel from the 318.

Anyone want to chime in with some advice?

[John_Kunkel]

1) Early 318 cranks were forged, later are cast but all are internal balance. The drilled holes in the 360 crank are normal, each individual crank is spin balanced using a specific bobweight.

2) Yes, just bolt the correct 360 balancer on.

3) Drill the flywheel as specified and you're good to go; my only concern would be the flywheel material, factory flywheels are cast steel but some aftermarket flywheels are billet steel...difference in density.

[elsensei]

Hey, thanks for the advice. I can tell from your answers that you actually took the time to read the post and look at the photos to figure out what I was asking and I appreciate that.

I will proceed with the build and I'll let you know how it all turns out. I will do some research on the question of flywheel density vs. stock and adjust accordingly. Thanks again!

[Cooter]

Don't know why you took offense to what I post d and quite frankly, I don't give two fu*cks.
I simply prefer to just get the correct flywheel, and I've never seen the engine side look like that so before you pm me acting like a
Douchebag, you might wanna try and understand why something is posted the way ut us and grow a thicker skin.
I have forgotten more than you'll ever know.




Will NEVER try and help you again. Have a nice day .

[John_Kunkel]

Only the engine side of a flywheel could look like that, the rear side of the flywheel will have a counterbored area for the bolt heads and the difference between do-it-yourself and new is $250. In this case, the trick to DIY is having the orphan size drill; but purchasing one is still cheaper than new if you already have a usable flywheel.