67 "DC" master cylinder casting dates

[Bill C.]

Hi,
Got a question on 67 master cylinders, the originals. I know that the 67's, at least the early ones, did not have any info stamped on the machined area surrounding the line inlets. My question is about the actual casting date. I have seen some I know for a fact are early 67's that have no casting date at all on them. And it seems the later ones all do. The ones that I have seen with no casting date have never had info stamped on them either. Is there anything someone can share on this? I cannot find any reference to this anywhere.
Bill

[William O.]

Re: 67 "DC" master cylinder casting dates

Well we know the reproductions do not have castings date codes, so when they started in 67' late and older, but the question should be "what is should be judged, or will pass the scrutiny.

[Bill C.]

Re: 67 "DC" master cylinder casting dates

Bill,
Thanks for the reply, I personally was not aware the repo's were not dated. The ones I describe are definetly not repo's. I am not interested in what will or will not pass judging , I am more interested in known authenticity and the historical value of the correct knowledge

[William O.]

Re: 67 "DC" master cylinder casting dates

Hopefully the more knowledgeable members can comment on this, since I own a 67' I have passionately pursued the DC and the PG master cylinders, especially the 67' to 72 Cylinders to understand the coding.
Regards,

Bill

[Gerard F.]

Re: 67 "DC" master cylinder casting dates

Bill and Bill,

I don't think the 67 Master cylinders had any date codes on them, earlier years and later years did.

Take a look at this post from the archives:

https://www.forums.ncrs.org/showthre...inder&uid=1077

There is also some earlier threads in the archives about this.

There is also nothing about the date code on the Master Cylinder in the 67 judging guide, as there is in other years.

I don't think it is a judged item, at least for 67's. I have never been dinged on it with my exact DC repro without a date code.

When I bought my repro a few years ago, I could have had it date coded. But from threads in the archives found out that 67's were not dated, so I didn't have it done.

[Joe L.]

Re: 67 "DC" master cylinder casting dates

Hi,
Got a question on 67 master cylinders, the originals. I know that the 67's, at least the early ones, did not have any info stamped on the machined area surrounding the line inlets. My question is about the actual casting date. I have seen some I know for a fact are early 67's that have no casting date at all on them. And it seems the later ones all do. The ones that I have seen with no casting date have never had info stamped on them either. Is there anything someone can share on this? I cannot find any reference to this anywhere.
Bill

Bill-----

Most "DC"-coded, '509' master cylinders do have a CAST-IN coding on them which MAY represent a date. It is the same 3 digit coding system seen on many Corvette brake calipers. Most likely, IF it represents a date, it's a julian date coding without any reference to year. Without reference to year and under current NCRS and NCCB dating guidelines, half of the master cylinders (or brake calipers) of the correct casting number and configuration would be dated "correctly" for any given car.

In the case of the known-original master cylinder for my original owner 1969, the cast-in "date" code is "141". The stamped-in date code is "9253". If the "141" represents a julian date code, it means the master cylinder was cast on May, 21 and machined/assembled on September 10, 1969 or 112 days after casting. That time interval seems long to me, but a strike may have affected it. My car was built about the 2nd week of September.

The 3 digit "date" codes on my known-original caliper halves are "all over the map". That also seems unlikely to me if they represent date codes.

In any event, if they represent date codes, there is no reference to year and, to me, that makes them fairly meaningless.

[Chris E.]

Re: 67 "DC" master cylinder casting dates

Hi,
Got a question on 67 master cylinders, the originals. I know that the 67's, at least the early ones, did not have any info stamped on the machined area surrounding the line inlets. My question is about the actual casting date. I have seen some I know for a fact are early 67's that have no casting date at all on them. And it seems the later ones all do. The ones that I have seen with no casting date have never had info stamped on them either. Is there anything someone can share on this? I cannot find any reference to this anywhere.
Bill

Bill, you have my curiosity peaked. I have a VERY early 67 (VIN 183). I know the ownership history back to 73 (it's been in our family). We haven't touched the master cylinder.

It is a power brake car. Here are the pictures.

Is it possible that this is the original master cylinder for my car?

[Bill C.]

Re: 67 "DC" master cylinder casting dates

Chris,
Wish I had different news for ya, no, that is not your original or anyone elses. It is a generic replacement, probably a Wagner unit. It also has a larger bore/piston than your original had, which would have increased pedal effort. Install a correct "dc" unit and you will be very pleased! I have originals rebuilt/sleeved/replated original covers if you are looking to go that route, or the new DC repos may be a cheaper alternative.
Good Luck!

[Chris E.]

Re: 67 "DC" master cylinder casting dates

Ok, well it was a shot.

[Joe L.]

Re: 67 "DC" master cylinder casting dates

Ok, well it was a shot.

Chris-----


This a Delco master cylinder. However, it was never originally installed on any 1967. The "clue" to that is that it has no bleeder valves. Original "346" master cylinders have the bleeder valves. These were used until about 1973 when they were eliminated from both PRODUCTION as well as SERVICE master cylinders. So, this master cylinder is likely a SERVICE unit from the 73+ period.

Also, while the "346" master cylinder was used for 1968-76+ Corvettes with J-50 or J-56 brakes, for 1967 it was only used for Corvettes with J-56 brakes. It has a 1-1/16" bore diameter. The master cylinder used for all 1967 standard and J-50 applications used a 1" bore master cylinder. So, it's not even the FUNCTIONALLY correct master cylinder for your application. However, it will work fine IF you have J-50 brakes. If you have standard brakes, it will cause increased pedal effort.

Also, there is a date stamping on the forward brake fitting machined boss. I can see it in the photo but I can't make it out. What is it?

[Chris E.]

Re: 67 "DC" master cylinder casting dates

Help me out Joe, which surface are you referring to? I don't know it by the name you used.

[Joe L.]

Re: 67 "DC" master cylinder casting dates

Help me out Joe, which surface are you referring to? I don't know it by the name you used.

Chris-----


Look at the forward brake line fitting on the master cylinder where the tubing nut threads into to retain the brake line to the master cylinder. Around the fitting there is a ROUND, FLAT machined surface. This is where the date code stamping is usually found. It will be very small, stamped characters. It seems like I can just barely see them in the photo but I can't make them out. It may just be a "photo-illusion", though.

[Chris E.]

Re: 67 "DC" master cylinder casting dates

Half of that stamp is missing, because it overlapped the opening for the fitting.

It reads PL456x (not sure what the last digit is,might be a 0, 6 or 8)

[Joe L.]

Re: 67 "DC" master cylinder casting dates

Half of that stamp is missing, because it overlapped the opening for the fitting.

It reads PL456x (not sure what the last digit is,might be a 0, 6 or 8)

Chris----


That's not a sequence that I am familiar with. In any event, it's not a sequence that was used during the 68-72 period. Usually, 1967's don't have any stamping.

[Chris E.]

Re: 67 "DC" master cylinder casting dates

The sequence I'm reading you is in the second picture from the bottom of my list, and is stamped upside down on the front brake line input port of the MC.

Thanks for the input. Regardless, I need a new MC.