Questionable Crank Markings on 383

[Ercouper]

I know I appear to not be active on this site, but I'm here almost everyday looking for information about my '65 Sport Fury with a 383 and 4-speed. I have learned much, but there are some issues I have that I cannot find answers to. I'm not going to ask them all at this time, but I'm to the point where I have to decide about purchasing engine parts.
First question is about crank markings. The first photo shows my engine ID boss. It doesn't show anything about non-stock bearing sizes such as a cross or diamond.


But on the crank counterweights, there are markings.


A 'Z' and what appears to be T. These are the counterweights on either side of the #1 and 2 rods.
Then there is this marking...

The letter C framed by half a square.

I assume these are processing markings and do not have anything to do with final sizing, but with the vast knowledge of this forum, thought maybe someone could verify what these are.
And yes, I have mic'd the rod and main journals and, unbelievably, they are within .005" of the FSM.
This engine had 80K miles on it and has been sitting for over 40 years.

I do plan on posting a progress/restoration thread for this car, mainly for my own reference, but I have very limited time to work on it as it is. I do try and take lots of photos, but need to organize them.
This photo shows what I am working with.


If you need more information, just ask.
Thanks,
Corey

 

[detmatt]

I really don’t think any markings on the crank mean anything to anybody post original assembly.

 

[Big_John]

A couple things I've read about those markings are that they use them to identify standard or undersize journals. One being for mains and one for rods etc.

I would bet the C in the diamond is an inspection stamp.

 

[CBODY67]

The markings on the ID pad, as listed in the FSM, are there to ID when a production block needs a few "touches-up" so it can be used rather than scrapped. Which could be important as to warranty repairs and such. Past that, nothing supported by the aftermarket per se. As some of those items would only be found in the factory parts book, as to sizes.

As to the crank stamps and such, they might reflect not only sizing but also the "balance" as it spins on its balance checker at the engine plant. If a certain imbalance might exist on some counterweights, then the noted connecting rods' weights can be adjusted accordingly. Again, only things which exist at the engine plant. Easier to have some connecting rods already "touched", ready for installation, rather than try to "touch" the balance weights on the crank, by observation, to get the same end result. This is why all OEM connecting rods have "balance pads" on them AND why my late machine shop operative would order a factory-matched set of rods for rebuilds (from his brother that was in the engine core business).

When the engine is rebuilt, with new pistons which are generally a bit heavier than OEM production over-sized pistons, there are balance pads near the pin boss on the piston's underside. Plus balance pads on the connecting rods. When those weights are equalized to specs, then the crankshaft is balanced as the final part of the puzzle. With the weight coming from the counterweights.

IF the crankshaft counterweights are "knife-edged" or rounded (David Vizard YT vid on this), then balance is also affected and those other balance pads (pistons and rods) can become much more operative, as to changes. Which can make a normal balance job much more intense.

Hope this might help,
CBODY67

 

[MONC440]

Good resource for block makings. Moparts on the Web - Main Index

I could not tell you what the crank marks mean, if anything.

 

[Ercouper]

Thanks to all of you for your reply. I have the Moparts site bookmarked, but the markings I see didn't have any reference. And I had heard, as Big_John said, that sometimes the bearing sizes were on the counterweights. My measurements verify that they are stock, so as DetMatt & CBODY67 thought, the markings are probably just manufacturing indicators for processing.
Thanks again.
I will be asking more questions later.
Ercouper Corey