Stamped Numbers on Connecting Rods

[Joe L.]

A question came up recently regarding the above referenced topic. Has anyone here ever seen stamped numbers (i.e. 1 through 8) on the sides and rod and cap on a first-run, never field-rebuilt engine? In other words, an engine which had those numbers stamped at the engine plant at the time of original assembly.

[Stephen B.]

Re: Stamped Numbers on Connecting Rods

Short answer NO
Stephen Barrett (21558) 59,66,71,73

[Terry M.]

Re: Stamped Numbers on Connecting Rods

I vote no also. In my youth I had a lot of Chevelle engines (big and small blocks) apart. We (my brother and I) kept breaking them.

[Timothy B.]

Re: Stamped Numbers on Connecting Rods

I have a 327 here in the basement and there are no stamped cylinder #'s on the rods.

[Domenic T.]

Re: Stamped Numbers on Connecting Rods

Joe,
That's a good one that is making me scratch my head.

I have stamps in my shop so there must be a reason for them but it's hard to imagine that all the ones I did with #s were done before.

All I come up with when I think back are the #s on the block that sized the pistons to the bore's.

DOM

[Tracy C.]

Re: Stamped Numbers on Connecting Rods

A question came up recently regarding the above referenced topic. Has anyone here ever seen stamped numbers (i.e. 1 through 8) on the sides and rod and cap on a first-run, never field-rebuilt engine? In other words, an engine which had those numbers stamped at the engine plant at the time of original assembly.

The GM sample rate coming from me can be counted on the fingers of one hand but still, I've never seen "prestamped" rods and caps on a factory build.

Why do I have the feeling you will pull a rabbit out of your hat and show us that it did in fact happen on occasion??

tc

[Patrick B.]

Re: Stamped Numbers on Connecting Rods

It is likely that only the special high performance engines, which typically had different rods, were marked. I took apart a number of 427 425/435 engines and a 70 LT-1 engine in the early 70's and all of them had numbered rods and caps. Today, I found a bent rod out of my first Corvette (a 67 427/435) that I had kept as a souvineir of hydraulic lock from leaky 3-2bbls. I changed it in 1971 and it was marked. Also, this rod and all of the markings I remember seem to use a slightly narrower font than the ordinary machine shop stamps. I also have a 69 ZL-1 engine I bought in the late 70's and its rods are marked in what I believe is the same font. I will look at my collection of rods in the next few days to make sure they support these observations.

[Wayne M.]

Re: Stamped Numbers on Connecting Rods

OK -- let's compare fonts -- if they are identical, then points to the same assembly plant.

Here's a few off a 396 May '65 block; been rebuilt at least once; 30-over and evidence of balancing done [before I acquired -- don't know the history].

Notice how the sets of characters are in perfect alignment and spacing; as if done in a gang holder designed for the purpose.

[John H.]

Re: Stamped Numbers on Connecting Rods

I've never built a big-block, but I've built a LOT of small-blocks over the last 45 years or so, and I've never seen a factory-built small-block with numbered rods and caps.

When I was the Senior Process Engineer at the Chevrolet Pilot Line in Flint in '66-'69, a good friend was the supervisor of the Piston Department at Flint V-8 next door, and I spent time there on several occasions. They didn't stamp the rods and caps when they machined the rods and made up the piston/rod assemblies for the engine assembly lines at 2400 rod/piston/pin/ring/bearing assemblies per hour; they just placed the size-gaged cam-ground pistons in the correct position in the 8-piston conveyor trays to match the teleprocessed bore sizes for that engine from the bore air-gage station at the head of the line.

In my experience, a small-block that exhibits number-stamped rods/caps has been through a rebuild somewhere, at least through the late 60's.

[Ralph B.]

Re: Stamped Numbers on Connecting Rods

Joe,
Yes, I do remember seeing them on my original owner 69 427 identically to the Wayne’s picture whereas I had this engine apart many times during my racing years. Additionally if my memory serves me correctly I remember some of the numbers were stamped somewhat lightly.

A question came up recently regarding the above referenced topic. Has anyone here ever seen stamped numbers (i.e. 1 through 8) on the sides and rod and cap on a first-run, never field-rebuilt engine? In other words, an engine which had those numbers stamped at the engine plant at the time of original assembly.

[Clem Z.]

Re: Stamped Numbers on Connecting Rods

the only reason to stamp them would be so the caps and rods would not get swapped on rebuild. like hink posted GM worried more about getting the correct pistons in the correct holes for fit.

[Patrick B.]

Re: Stamped Numbers on Connecting Rods

Wayne's observation that the numbers on the rod and cap line up like they were in a holder is very telling. The numbers on the 67 435 rod I have at home line up just like Wayne's. Furthermore, the height of the characters is 5/32 and the center to center spacing was exactly 5/16. They are the same standard size 5/16 high and 50% aspect ratio as the 61 - 67 VIN characters, although they differ somewhat in style (a different vendor for Tonawanda versus St. Louis?). But, here's were it gets interesting. The VIN characters were on pieces of type 5/16 wide in a 7 cavity holder. If one used a three cavity holder for these industry standard 5/16 character pieces of type with a blank piece of type between two numbers, the result would be exactly what is on my rod and what I think Wayne's rods also demonstrate. There is no machine shop I can think of- let alone many shops around the country - that would go to that amount of planning and tool procurement just to reduce the rod marking labor from two strikes per rod to one strike per rod.

I realize that this is a broad conclusion from a small number of observations, but I do not think it is a coincidence, and I will check the various rods I have in storage. People with marked rods can simply check to see if the numbers are slightly more than 1/8 inch high, are in alignment along a straight edge, and are spaced 5/16 inch apart center to center in order to test my theory. I was so used to seeing these numbers on SHP big blocks that they seemed normal on an LT-1, but maybe they are rare on small blocks.

[Patrick B.]

Re: Stamped Numbers on Connecting Rods

I looked at about 60 big block rods and about 50 small block rods today including a '70 350-300 Corvette engine that had never been apart. I don't know how people could have thought that no Chevy rods were marked in the factory.

Every big block rod I had was numbered ----not just the the "double bump" or dimpled rods out of solid lifter engines, even the rods out of low horsepower 396's were numbered. 90% of them were numbered like I described in the previous post. All were in alignment consistent with a holder and all were 5/32" characters with 50% aspect ratio. A few were spaced closer than 5/16 and one was spaced wider. There was at least two styles of numbers indicating more than one stamp vender, and two styles of the same numeral were sometimes found on the same rod.

The small block rods were very different. I found no numbered rods including the never disassembled 70 short block. Also the ground sides of the rods would probably be too small for numbering with the stamp holder used on big blocks. I know the rods on my 70 LT-1 (V0615CTK) were numbered, but I did not remove the pan to inspect them. If anyone has any observations of 70 LT-1 rods, please share them. One of the rods I looked at was a pink rod out of a 71 or 72 LT-1 and it was not numbered.

[Joe L.]

Re: Stamped Numbers on Connecting Rods

All------


Thanks for all the good feedback. I did not think that any Chevy V-8 rods had the numbers stamped on them. However, like John, I have far more experience with small blocks than big blocks and I've never seen such stampings on any first-run small block rod. I didn't recall seeing them on big blocks, either. However, it's been quite a while since I tore down a first-run big block. So, maybe I just missed it.

[Robert G.]

Re: Stamped Numbers on Connecting Rods

I had my oil pan off earlier this year (67 BB) and saw the rods had been stamped and just assumed a rebuild had taken place. Now I don't know. I should have taken pictures I guess.