360 steps for machining crank

[67/6barracuda]

Help me understand the process of machining a 360 crank. Just got off the phone with Atlanta Speed Shop in Gainesville GA asked if they would clean up a 360 crank, might get away with a polish or may need to be turned not sure. I’ll leave that up to them.

Additionally, I have the H116p speed pro .030 flat top pistons that I need set up on a set of rods if the rods can be reconditioned. If not I’ll buy new rods.

Well he said the cheapest I’d get out of the shop is a $1,000 dollars. I was thinking before I called maybe 4-500 dollars/ish maybe more if I need to buy new rods.

He was going on about run out, balancing and mic-ing the crank and all when he kind of lost me.

My question is so what would he need to reconditioning the crank/balance do i bring the balancer, the crank bolt, the flex plate and bolts. I didn’t think to ask at the time.

Didn’t think the crank would need balancing with the h116p’s did some reading on them most say they’re pretty close to stock piston weight. Best practice is balancing though I get that. Just sticker shocked a little.

They were highly recommended locally.

I may check a few other shops.

 

[RustyRatRod]

You're kinda unclear in what all you are letting the shop or want the shop to do. At first you just talk about just turning the crank and then it snowballs. So from what it sounds like the shop is talking about turning the crank and balancing the rotating assembly for a grand? Is that right? I'd say that's reasonable.

 

[abdywgn]

He was going on about run out, balancing and mic-ing the crank and all when he kind of lost me.

run out in my mind would be checking to see if the crank is bent or journal(s) is egg shaped. mic-ing the crank would be checking the diameter in three spots(?) on each journal; probably 12,4 and 8 o'clock.
I rebuilt a 273 and did none of the above, just a "parts store" rebuild kit. crank was tight, out of round. had to take it back apart and have it cut.

 

[67/6barracuda]

With the balancing do you bring everything, balancer and flex plate and all being its externally balanced.

 

[NC Engine Builder]

Checking and grinding the crank would be a few hundred, ballancing about the same. That job would be about 500-600 total in my shop.

 

[abdywgn]

yes, but if the pistons lighten it up enough, maybe it could be internally balanced. and that might be an option for a down the road swap?

 

[NC Engine Builder]

With the balancing do you bring everything, balancer and flex plate and all being its externally balanced.

If it's going to stay external ballance, you need flexplate, harmonic damper, one rod, one piston, one set of locks if floating rod, one set of rings, and one pair of rod bearings. If you want to be super particular, you should weight match all 8 rods to the lightest one, and the pistons also.

 

[RustyRatRod]

With the balancing do you bring everything, balancer and flex plate and all being its externally balanced.

Yes. He will need all of it, including rings, bearings and anything that bolts to the crankshaft. If he says he does not, might I suggest Scott's Machine Shop in Fayetteville? lol

 

[PRH]

It’s usually a good idea to bring everything, even if you’re not planning on weight matching everything.
Then they can at least weigh all the parts to see if an item is way off from the others.

 

[67/6barracuda]

Thanks guys. I’ll bring the entirety of the rotating assembly so they can harmonize these parts for balance. I’d didn’t order any bearings in case they decide to grind the crank. I’ll let em know to order up the bearings if needs grinding.

 

[67/6barracuda]

Yes. He will need all of it, including rings, bearings and anything that bolts to the crankshaft. If he says he does not, might I suggest Scott's Machine Shop in Fayetteville? lol

Rusty, Scott’s is an option and closest to me. They did a set of heads for me in the past. They have mixed reviews but they are capable I’ll check with them.

 

[RustyRatRod]

Rusty, Scott’s is an option and closest to me. They did a set of heads for me in the past. They have mixed reviews but they are capable I’ll check with them.

Well, just remember, you caint please everybody. lol

 

[dogbreath]

The speed pro h116cp pistons are very similar in weight to the stock pistons and you could possibly get away with out a balance job except if the rods are replaced. There have been many 360 engines built using those pistons and not balancing without issue but of course a rebalance is always a good thing. What about the bore???

 

[NC Engine Builder]

Except the factory ballance job wasn't very good to begin with. Its money well spent in my opinion