Engine Balancing

[Boilermaker]

Get a call from the machine shop this afternoon, turns out Hesco sent me mismatched piston pins. One of the six pins is 3" long, the other 5 pins are 3.185" (the diameters for all the pins was .930) Called over to Hesco, Bennie confirmed the pins are supposed to be 3" and is sending out 5 new pins at no charge (very good of them).

The machine shop told me that since difference was so small and that the correct pins were lighter that what they had used for balancing, it wouldn't need to be done again. How concerned should i be that the machine shop didn't notice this until after they balanced everything? Should i have everything balanced again when the correct pins arrive?

Thanks in advance

[SilverXJ]

I would have it rebalanced, but I am a perfectionist. I would also talk to Hesco about their opinion on re balancing and if they would reimbursing you the extra balancing charge.

[Boilermaker]

Never thought about getting Hesco's opinion on it.

I'm leaning toward rebalancing; i'm pretty much a noob but from what i've read so far it seems too important for close enough to cut it . Problem is that i had the pins and pistons in hand (for a whole hour) before running them down to the machine shop. Never thought to do anything other than to count the pistons and pins and take a picture in case i ever did a build thread. I'm picking up the pins and all the packaging up tomorrow; when i do i'm going to double check the box against the invoice to see if this is something i should have caught.

btw, here's what i ordered from Hesco:
4.5L Stroker Engine .030 Forged Piston Set #HESDP45030
4.0L/4.2L Standard Size Piston Pin #P2208 3

Ironically, I called Hesco prior to ordering for among other reasons, to confirm i was buying the right pins. Turns out the pins i was about to order were wrong and the ones listed above were what i was told to get.

[gradon]

I like your part selection--that MJ will be fun to drive.

[Boilermaker]

I like your part selection--that MJ will be fun to drive.

Thanks. After 5 months of having the truck in various states of dis-assembly for paint and the stroker, i'm hopefully only a month away.

[Muad'Dib]

If you have a machine shop do the balancing, do you need them to also install all the internals, or can you do that youself and then bring it in and say balance this bitch!?

Sorry for the noob question!

[Bodo]

you need to bring in the crank, rods, pistons(with rings) and harmonic balancer (sometimes they want your flywheel too). They'll weigh and match the pistons/rods.
Our inline motors don't need bob weights, so that makes it really easy.

[Muad'Dib]

So no assembling myself huh?? That takes the fun out of it

[Mgardiner1]

Yes, all assembling yourself.

They simply weight match the rods and pistons so they all weigh within a certian spec of each other. The crank will be balanced by itself with or without harmonic balancer and flywheel. Then all parts can be handed back to you, or you can have the machine shop assembly the rotating group for you (for extra $$$)

[Muad'Dib]

Oh i see ..

So you take all the parts into them to have it balanced. They balance the parts and give them back. Then you assemble.

Sound right?

[Bodo]

You got it

[Muad'Dib]

Yeah! i lerned sumting tuday.. nw f i culd nly lern 2 spel~!

[aaronkeiser]

For my motor I just weight balanced the piston/rods/rod bolts and it spins up nice with no vibrations.

[Retlaw01XJ]

And here I thought I'd have to pay $200+ to have the assembly balanced due to the new Scat crank and KB forged pistons....
Then my machine shop tells me inline engines don't need to be spin balanced like V8's do! I never knew that until today. Interesting.
So, for an inline, the crank is balanced by itself. And rods/ pistons are balanced to each other. No bob weight calculations and spin balancing necessary. Cool!

[LeviPittman]

i had my guy check all the tollerances, clearance as needed cc the head, check for straightness front to back, get me a pushrod length, and check the spring pressures it cost me a few bux but saved me replacing the cam shortly after breakin seat pressures were WAY too high and if i hadnt had all that done id have spent way more buying MORE tools i RARELY use - its one of those just cause i can doesnt mean i will things

id spin it too just to be certain.....