Any body have a picture of an original MC for a 74? I think mine is bad and trying to determine to rebuild or replace. Not NCRS but like to keep or rebuild as many original as possible. I don't see any GM marking on it but MADE in USA 29969 is cast in the body.
Thanks
Mike

 

Sorry, but with those markings, it's not the original master cylinder. It sounds like the generic MC available through most auto parts stores.

The original MC was made by Delco and would have had a casting number cast into the right side of it, 5455509 for non power brakes, and 5480346 with power brakes. It would also have the Delco split circle logo cast alongside of the casting number. Depending on when in 74 your Corvette was built, the master cylinder may have had two bleeders in it. The bleeders were eliminated at some point during the model year, but I'm not sure about when.

You have three choices for a replacement master cylinder. You can buy the generic replacements from most Corvette vendors, or any local parts store, for $100 or less.

Your second choice would be the repro Delco MC, which is available with either casting number, and with or without bleeders. These are excellent repro's, and sell for less than $150.

The third choice is to buy a restored original MC. The best ones are stainless steel sleeved, and sell for $250-$300, plus a core charge($50??). The rebuilt is a better choice if your trying to maintain an unrestored or more original appearance. The castings used for rebuilt ones are 'aged' and look it, unlike the repro's, that are a made from nice, new, crisp and pristine castings.

 

Hi S,
As gb said, and I posted to your last thread, the master cylinder will have the Delco Moraine split circle logo on it if it's an original.
It may be small and faint so look carefully.
Regards,
Alan

Look for a split circle like this one.

 

Here is a picture of a 509 non power master cylinder, showing the casting number, and the Delco logo. Other than the casting number, the 346 power MC looks exactly the same.

On the left side there may be a cast, 3 or 4 digit number. I don't believe this number has much meaning to the hobby, as it was either a mold number, plant number, or something like that. MC's were sometimes dated, but it was with a date stamped on the machined fitting surface.

The version of the MC without bleeders, looks exactly the same, except the flat surface where the bleeders are, is not drilled or tapped for bleeders.

 

Hi,
Here's another original 509 to go along with gb's.
Maybe the logo is a little clearer on this one.
Regards,
Alan

 

Thanks for the help and pictures. It is most certainly an after market part. Well I will replace with another aftermarket but am on the look out for an original to rebuild.
Thanks
Mike