67 small block factory marks.

[Bill H.]

i did a search and saw the crayon marks on the sides of the block. Mine is a 67 base motor (pic attached).
I'm curious as to what the blue paint on the rear of the block denoted.

[Bill H.]

Re: 67 small block factory marks.

Also, the bore size designation on the oil pan rail, is there info on what the numbers mean size wise?

[David L.]

Re: 67 small block factory marks.

The "HE" yellow crayon marking should obviously match up with the "HE" (1967 Corvette 327 w/M.T.) stamping on the front "pad". I have seen numbers stamped on the oil pan mounting surface of blocks that I have had but have never came to any conclusion of what they mean.

Dave

[Bill H.]

Re: 67 small block factory marks.

Yea, the HE matches the pad stamp.
The numbers are "bore size designations" to match to piston sizes. I'm just curious if those numbers can be translated into a measurement.

[John D.]

Re: 67 small block factory marks.

I'm guessing the blue paint spritz could be a visual inducation that a torque value or inspection process was completed on the case.
In the assembly plant i worked in back in the 80's some critical chassis fasteners had a paint sprayer hooked up to the tool that would spritz
a small blast of paint once the torque value was reached.

[John H.]

Re: 67 small block factory marks.

Also, the bore size designation on the oil pan rail, is there info on what the numbers mean size wise?

Bill -

I don't have the old cross-reference charts, but Ken Kayser might. In those days, there were eight different bore sizes within the nominal bore size tolerance range, and the pistons for each engine were size-matched to each bore; the bores were measured by an air-gaging system in the first station on the engine assembly line. Those size codes were stamped on the pan rail, and were also teletyped to the Piston Department, where the pistons were machined and cam-ground to precise size, ringed, and assembled to the rods. The eight piston/rod assemblies for each engine were placed by cylinder number in a wire tray on an overhead conveyor that took them in engine sequence to the engine assembly line, where the installers "stuffed" them in the bores (see photo below) and installed the rod caps and nuts.

Improvements in machining processes and in process control since then eliminated tolerance-sizing of bores and pistons decades ago; modern engines have one bore size and one piston size, and there's no longer a need for selective fitting of pistons.


PistonStuffing800.jpg

[Terry M.]

Re: 67 small block factory marks.

Too bad there isn't a video or movie of that "stuffing" process. It is like a 4-man ballet. Every guy has a task in sequence and it was a thing of beauty to see. John's still photo doesn't do it justice. There were a number of 4-man teams (I would guess perhaps 6 teams) and while most worked the other took a break. Seeing that teamwork gave a new meaning to working on the assembly line. It just might change your opinion of UAW workers too.

[Bill H.]

Re: 67 small block factory marks.

Bill -

I don't have the old cross-reference charts, but Ken Kayser might. In those days, there were eight different bore sizes within the nominal bore size tolerance range, and the pistons for each engine were size-matched to each bore; the bores were measured by an air-gaging system in the first station on the engine assembly line. Those size codes were stamped on the pan rail, and were also teletyped to the Piston Department, where the pistons were machined and cam-ground to precise size, ringed, and assembled to the rods. The eight piston/rod assemblies for each engine were placed by cylinder number in a wire tray on an overhead conveyor that took them in engine sequence to the engine assembly line, where the installers "stuffed" them in the bores (see photo below) and installed the rod caps and nuts.

Improvements in machining processes and in process control since then eliminated tolerance-sizing of bores and pistons decades ago; modern engines have one bore size and one piston size, and there's no longer a need for selective fitting of pistons.


[ATTACH=CONFIG]40876[/ATTACH]

Thanks, John, it was just idle curiosity.
I agree Terry.