The numbers above make my JM Forged .060 OS 312 with 4cc dome seem light.  641 gm with pin and clips.

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Hollowhead,

Thanks for pointing that out; my appologies if this caused confusion for anyone else besides me.

Thanks again to all for their comments.

Regards,   JLB

55 Ford Crown Victoria Steel Top

Sorry, but you just asked piston weight, not with pins and locks . And 585 was what Mummerts list gave us

 Seppo from Järvenpää, Finland
www.hollowheads.net (just click the hole in the head to proceed)

I'm intending to look into balancing locally; in the meantime, I've gleaned quite a bit from this discussion.

I just got to thinking that I've been working on Y-blocks for 50+ years now (wow, where does the time go???); but, still a lot to learn from the "smart guys" on here.  My 44-year-old eldest son is now working with me on this  --  he'll most probably inherit the car, as he's the only one interested, besides one of the grandkids / maybe.

Thanks everyone!

I'll let folks know what's happening  -  won't be for a few months yet, though.

Regards,   JLB

55 Ford Crown Victoria Steel Top

I am sure there is a local balancing shop near you, cheap insurance. I bought a brand new pressure plate and clutch and brought it to my local balance shop and you would not beleive how far that NAPA Chinese pressure plate was out of balance from the factory.

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?

I'm in the Great White Frozen North; roughly 1,000 miles due north of Ted on I-35 northern terminus, just outside of Duluth MN, right at the headwaters of the Great Lakes.

Very unusual winter so far: Almost NO snow, and temperatures WAY above normal.  In the 20's & 30's (up to above 50); normally have a few weeks of steady minus temperatures right now (many times a week or two of -30  -- have been called out to work once at -65!!!!!   --  cannot even try to describe how cold that is).

I'vew learned a lot about what Southern folks go through with hurricanes, heat, and varmints; we go through "different" issues with winter; but, no hurricanes, very little summer heat (we like it at 65 -- 75 degrees), and no varmints - other than misquitoes can get nasty sometimes.

Regards,  JLB

55 Ford Crown Victoria Steel Top

JL, Tell us where you live, Ted's in Texas.

Frank/Rebop

Bristol, In ( by Elkhart) 

I looked through the scrap aluminum here and there are no stock 312 pistons laying loose here so no help there.  The 585g piston value plus the 143g wrist pin weight posted on John Mummert’s site would be a reasonable target though.  Err to the light side for the piston and pin weights when match balancing as the existing crankshaft balance can tolerate lighter rods/pistons versus pieces that are heavier than stock.  If you have a 312 with std bore pistons, then those would be the ones to weigh as nothing says the weight spec didn’t change throughout the years of production.  Be sure to weigh and include the factory piston ring set and locks in your values as those component weights do vary between manufacturers.

 

But Charlie’s overall assessment is correct.  Having the engine balanced by an independent shop will insure a much more precise balance job than what the factory originally supplied.  Factory weight variances do tend to vary for a variety of reasons.

Lorena, Texas (South of Waco)

At the minimum, you can try to match them to the weights of your current pistons. Forget the weights other people have measured. You must know it worked reasonably well with what you had so make your old pistons your baseline.

If you are machining any of the other components, then I'd suggest rebalancing. You'd be surprised just how much a simple machining operation can throw things out of whack. If it is cost prohibitive, I can understand but if not, balance it. You'll be glad you did - you'll notice just how out of balance it was.


Lawrenceville, GA

Thanks very much to all!

In looking at the various information presented, it looks like I have more work cut-out for me as the weights listed are all-over the place  -  including a researched previous post indicating ranges of from 675 through 710 grams.  The information returned to me in this post shows a much wider variance ("hollowhead" down to 585 grams), of which I'm not now sure what to do.

Ted, I know that I should ideally have the crank re-balanced (and you are prohibitively too far away for me to afford the shipping and balancing costs); have you any further suggestions either having it balanced locally; or, what pistons to use with the existing factory crank (I have no problem doing a very precise static balance of pistons and rods?).

Regards,   JLB

55 Ford Crown Victoria Steel Top