C3C2

I am trying to verify the originality of my master cylinder. The cast part number is correct, but I cannot locate the date code.

Can anyone help?

C3C2

I found 0192 etched on the machined surface on one of the fititngs. Can I assume this is january 1992?

JmpnJckFlsh

This may be false hope for you, C3, but I doubt that a MC made in 92 would be dated like that. I suppose it's possible, but I am skeptical that GM even dated those old replacement MCs in 92.

I don't know how original MCs were dated, but this may be a four digit Julian date where the first three digits, "019" is January 19, and the last "2" is for 62, or 72, or ? Another possibility is that the "0" is for 70 or 80, and the "192" is July 10. But, if my theory is right, then this MC is too early or too late to be original on either your 64 or your 69. It works for a 62 (too early for 63), or a very late 70 or early 71, or a parts counter replacement.

On which car is the MC installed? On which fitting surface are these numbers etched? I am very interested in what others have to say. It will be a learning opportunity for me.

noskillz

I even remember reading in my "1969 Stingray" guide that during several shifts the numbers got switched around. I look up the ref when I get a chance.

Chuck Gongloff

As I remember original MC's had the number stamped, not etched. Replacement MC's have the date CAST...like the casting number. I also remember the rightside up, upside down casting number designating day or night shift. Bizocco's book says there is a Julian date.....which varies with day/night shift. If it's day shift, the year PRECEDES the date 9123, the 123rd. day of 69. If it's night shift, the year FOLLOWS the date, 1239. Confused yet? Day shift has the casting number rightside up...can be read "normally" while in the car. Night shift is upside down...reads upside down when in the car. Chuck

GaryS

If, by etched you mean stamped with a metal stamp, then I would suspect that the 192 is the Julian date. That is the 192nd day of the year. If all else about the MC looks good, configuration and all, then ASSUME that this is the correct MC. What does the judging manual state about the MC's for your year. I didn't see the year of the car we are talking about, but the MC on my 72 has the Julian date stamped on a machined surface at the front of the MC. It corresponds with other dates in the car and is properly configured.
Gary

C3C2

The car is from 1969

Here is a pic: http://temp.corvetteforum.net/c3/wprattjr

The date code is machined, not etched. According to my judging manual all else is correct i.e. cast number and other marks.

The buid date on the car is April 1969

Thanks

JmpnJckFlsh

Based on your build date, and assuming the number you have given IS a julian date, I suspect that your MC was replaced very early with a new GM part, or it was replaced later with a rebuilder's part. When owners go to Pep Boys for a rebuilt unit, the core the rebuilder started with could be dated anytime during the period the part was used, or even afterward, if the replacements were dated.

In the 70-72 TIM&JG, there is no mention of date information for any year except 72, and for that reason, I am skeptical that earlier MCs were even dated. You never responded to my question about where this number was located on the MC: In the 70-72 TIM&JG, the date is described as being on the machined surface for the front tube connection below the two letter stamp. Typically, date codes during this period would be stamped rather than etched or machined, which may indicate later technology.

I am not familiar with the current judging practice regarding MC dates. In past years, I don't think many judges even knew they were dated. If the judges were really thorough, they checked the casting number, they checked for the zinc plated bleed ports, they checked to see if the machined areas were painted or bare (if the MC was supposed to be painted), they checked to see if it was stamped with the proper two letter code for power or manual brakes, and oh yeah...they checked to see if it had the repro bail tag installed. :D

If it were me, and the MC has the correct casting number, and has the zinc plated bleed ports above the brake line ports, I would be inclined to accept the MC as almost completely correct, and have it restored with stainless sleeves. If in the future, you happen to find an MC that is dated properly, you can always upgrade and ebay this one. I expect the deduct on the date will be minor (worst case: a deduct for having a date if 69s aren't dated; a deduct for incorrect date if they are).

However, if this is going to bug you, you could also check with White Post or Master Brake and see if they have one better dated to fit your car, and will exchange for your core. It will cost you another hundred or so, probably, and it may be worth it to you. But seriously, only you and your judge(s) MAY know that your MC is not properly dated. :D :D


[Modified by Chuck Sangerhausen, 7:17 AM 3/20/2002]


[Modified by Chuck Sangerhausen, 7:22 AM 3/20/2002]


[Modified by Chuck Sangerhausen, 9:55 AM 3/20/2002]

noskillz

Thanks, Chuck. I remembered somthing wierd about the date :conehead