Chronology of engine ID pad stamping

[Steve Antonucci]

Hi everyone,

I have a question regarding the process of stamping the engine ID pad on big
block engines. This probably applies to small blocks as well. The time period
I am concerned with is 1968-1972.

As we reviewed here a few months ago, the engine assembly process at Tonawanda
eventually entailed the painting process. At that time, it was identified that
the accessories on the front of the engine ( p/s, alt., etc. ) were not present.
So, did the engine painting process actually cover the engine ID
stamping pad as well?

The questions I have concern the engine assembly date & code.
Was that added after the engine was painted, or before it was painted? If added after
painting, would that possibly explain why some codes are stamped shallower
than others? What about the addition of the VIN stamping to the engine pad.
When would that process have been performed? It would obviously have to be
on the assembly line somewhere close to where the engine was mated with its
chassis. In the case of non-Corvette applications, would the upper alternator
bracket have to be removed to acomplish this VIN stamping? I've seen many
VIN stampings over the years. Some are fairly shallow while others are not.
Could engine pad painting play any part on the depth of these stampings?

Steve

[Warren F.]

Re: Chronology of engine ID pad stamping

Steve,

Somewhere someone posted a picture of the stamping being done (I believe the vin), my opinion is that the inconsistency of the hammer blow, and the gang holder being held flat against the steel pad, has more to do with the stamping depth than possibly the additional painted surface, if indeed it was stamped after paint. I thought it was Michael Hansen that had the photo, not sure though.

[Steve Antonucci]

Re: Chronology of engine ID pad stamping

Hey Mike! You out there?

[Terry M.]

Re: Chronology of engine ID pad stamping

Steve you will find the answers you seek and more regarding the painting process for both big and small block Corvettes in the applicable TIM&JG. The short story for BB:

Cylinder case assembly stamping for BB was done before the heads were installed -- and thus before paint. Engine paint instructions called for certain areas of the engine to be unpainted -- among those was the stamp pad.

This applies to all big block engines regardless of where they were destined to be put between the frame rails. All complete engines were painted in the same fashion.

The VIN derivative was placed on the cylinder case (and transmission) at the vehicle assembly plant -- right after the transmission was mated to the engine. The engine then had to be dressed -- which includes the accessory drive and of course applicable driven units for that particular vehicle.

[Steve Antonucci]

Re: Chronology of engine ID pad stamping

Terry,

If the cylinder heads were not yet installed, how did the L/89 codes get figured out ahead of time?
Also, how was engine paint "masked" from getting on the engine pad? Was tape used?

Steve

[Joel Falk]

Re: Chronology of engine ID pad stamping

Steve,

IIRC, the short block had the suffix written on the side in crayon (upside down).

[Terry M.]

Re: Chronology of engine ID pad stamping

Joel has the answer to the L71 or L89 question as well as the same question as it relates to transmission style. Someone estimated how many of a given engine horsepower and transmission style would be needed for the vehicle build during the next couple of weeks -- based on customer orders, and placed the order with the engine plant. Those engines were built and shipped. As they were installed the cycle continued.

I believe in most cases the pad was covered with masking tape, or something like that, but I wouldn't rule out a coating of grease either. There were other areas masked during the time period you mention -- spark plug holes, engine mount bolt holes, oil filter opening, and the front of the harmonic damper are a few. There were other places as well.

[Gene M.]

Re: Chronology of engine ID pad stamping

Terry, Were not the spark plugs in place in the cylinder heads when the engine was painted? They are not in the final assembly listing of parts to assemble.
There for I would expect spark plugs to be assembled at the engine plant with possible orange overspray...........

[Terry M.]

Re: Chronology of engine ID pad stamping

The answer, Gene, depends on the year of the engine manufacture. Since the original poster specified 1968-1972 big block -- the answer is no, the spark plugs were not in the heads during engine paint in those years.

For some earlier years (and I don't know which years those were) they were installed before painting and shielded with little cardboard tubes during the paint operation. Those tubes sometimes blew off, and it was subsequently found the engine paint was electrically conductive -- shorted the spark to ground at the vehicle assembly plant. Thus the procedure was changed and the spark plugs were installed at the engine assembly plant, but after engine paint.

Distributors at times were installed before paint, and other times after paint. 1968-1972 distributors were installed after paint. Exhaust manifolds were another sometimes before and sometimes after situation.

The changing engine paint procedures over the years is one of the reasons I suggested in my first response that one check the applicable judging guide for that information. That should provide one with the paint details which are specific for those years of cars, and even specific to the engine. Flint and Tonawanda paint details were different, so one needs to specify not only the year, but the engine family when talking about engine paint details.

[Patrick T.]

(Message Deleted by Poster)

Message Deleted by Poster

[John H.]

Re: Here is the gang stamp...

That's the St. Louis engine dress line VIN derivative gang holder, photo provided to me by Michael Hanson.

[Steve Antonucci]

Re: Here is the gang stamp...

John,

Was there supposed to be a picture attached to your message?

Steve

[John H.]

Re: Here is the gang stamp...

Steve -

The photo I referred to was in the post previous to mine, which has been deleted by the poster; here's the photo: