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

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"

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

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

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) 

Tim.  Feel assured that I didn’t take it to mean that you are not in favor of balancing.  I probably came across sounding like it has to be balanced or it will fall apart right away.  In Paul’s case, he is to be commended for at least trying to minimize weight variances in the rods and pistons himself while knowing that he’s not in a position to rebalance the crankshaft at this time.  This is much more than what happens on a majority of rebuilds and at least match weighing what he can will still help in the long run.

Paul.  Don’t be overly concerned about the differences in balance pads as a variance in balance pad heights within a given set is common.  And it’s not unusual for the rod with the largest pad to actually be lighter than the heaviest in a set.  This has to do with how the rod was initially laid out when the machine work was started and the distribution of the weight on the rest of the rod as a result.  Let us know what you actually find on the rod weights in regards to pad height versus the weight and how much variance in grams you actually find from the lightest to the heaviest.

John.  I’ve been told the same scenario on the factory balancing of crankshafts in regards to hole drilling without actually balancing.  Essentially, a rack of cranks would all be drilled the same based on a sample crankshaft that was actually balanced.  I tend to see this on the 350 scrub engines as a majority of factory balance holes appear to be identical both in depth and location.  In all the years I’ve been balancing stock engines, there’s only been a few (three come to mind) that actually would have been okay as delivered from the factory.

Maybe Dennis K. can chime in and give the real story on what at least happened at Ford in the balancing department during engine assembly.

Lorena, Texas (South of Waco)

Here is how it's done.

   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

That's what the "extra" material is on each end… for you to subtract from.

       A  L  A  N   F  R  A  K  E  S   ~  Tulsa, OK    

It could have been the lightest rod.

You'll need to devise a fixture for weighing the rods. They don't simply get matched for weight. You match the big ends then do the small ends (or vice versa - it doesn't matter which end is balanced first). Find the rod with the lightest big end, match the others to it. Find the rod with the lightest small end, match the others to it. When done correctly, all rods will weigh the same.


Lawrenceville, GA

I was guessing what John was suggesting; the factory sampled the weights of the parts and balanced to that sample weight. That might be part of the reason that piston weights are published; to ensure that the factory balance is not thrown too far off when buying replacement pistons.



Thanks to all for their wisdom. I'm going to cut this corner this time because I need to get my F100 back on the road as cheaply as possible. I'm going to static balance the parts to each other and call that good. (One of the rods looks a little different than the others - the balance pad on the big end was not milled down at all. I'm guessing that the previous rebuilder grabbed a replacement rod from inventory and didn't worry about balance. I suspect that rod will be a tic heavy on the big end.)

Best regards,



Paul Menten

Meridian, Idaho