Ted,

      I know you've covered this before, but explain to them why you have to balance dynamically and why the factors change for different end uses. (Randy's rail vs. a truck engine.) 

Frank/Rebop

Bristol, In ( by Elkhart) 

Ted,

In the years I've been balancing I too have seen very few Factory balance jobs that were OK and none that are spot ON, But I wonder if you would agree that they did a much better job in the late '50s and through the '60s than you see in the late '70s and '80s. I would say that a 1963 327 scrub is much closer to right on than a 1982 305 or 350.  Also I would like to add, while on the scrub subject, that 305s (5.0) and 350s (5.7) use the same casting # crank and I have seen guys unknowingly swap the two may times, they seem to run somewhat OK when a 350 is in a 305 but the other way around and LOOK OUT.

Disclaimer: I use the scrub for example only because, I'm sorry to say, I see a lot more of them.

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

Were they externally balanced in the 60s? I know the late 80s sbc is. That could make things appear to be worse, if not taken into account.


Lawrenceville, GA

Tim:

Of course you see more chevvies.  They break more.  When I was in the auto repair business in the late '60s and early '70s, I often remarked how much I liked chevvies, if I relied on Fords for business I'd starve to death.

John

John - "The Hoosier Hurricane"

It turns out that the rod with the unmachined balance pad is among the lightest of the set; 678.5 grams. The total weights varied between 678.5 grams to 683.2 grams. The rods are a real mixed bag. One has the name ATLAS cast into the beam, two say Made In Canada, I don't see more than two that look like an exact match. I've seen two area of difference that explain weigh variations; the cap on some rods are beefier, and the thickness of the beams seems to vary a bit from rod type to rod type.



I'm having a heck of a time trying to weigh just the big end or just the small end. I've tried a few quick tricks but I'll have to rig up a rigid fixture like the one Tim showed to get a consistent reading.



Wrist pin weights vary within 1 gram. Pistons weights are very close. It's the rods that are giving me the most trouble.



Edit: Forgot to mention, there was also a variation in the length of the rods bolts. Weird.

Best regards,



Paul Menten

Meridian, Idaho

Paul,

        Put the rods in a box and send them to Ted, or Tim. It will probably cost you less and you'll be pretty sure it's done right. Either one of these guys will treat you right.

                                   Frank

Frank/Rebop

Bristol, In ( by Elkhart) 

Paul,

If you do as Frank says and send Me your rods and return shipping I have a matched set that I'll trade you. They are not resized or have new bushings, but I will make sure they are good to use and weigh the same. I could use your rods as a broken set for when I need one to replace a bent or burnt one in another set.

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

The only SBC, other than the 400, that is externaly balanced would be the 5.0 and 5.7 with the one piece rear seal made '86 and later. They have a weight on the flywheel/flexplate only and because of a differant size flange you can't swap the flywheel/flexplate with the earlyer model SBC.

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

Tim.  That’s exactly my experience also.  The earlier engines as a whole do exhibit less variance in both the static weights and crankshaft imbalances versus those that were made in the Seventies and Eighties.  This just points to quality or tighter controls being more in the forefront on the earlier engines than the later.  The engines I find that exhibit the most imbalance as a whole are the Mopars.  Tolerances or allowances at that camp appear to be much wider than at the other two camps.

Lorena, Texas (South of Waco)

To add to what Tim mentioned, here’s a balancing article that goes into more detail on some of the nuances that exist with external balancing.

http://www.eatonbalancing.com/blog/2007/11/20/engine-balancing-part-2/ 

Lorena, Texas (South of Waco)