Master Cyl
 

Getting my MC ready for a refresh and I noticed it does not have bleeders. From what I read it should. It’s a Delco,has the right numbers and I believe was original to the car. In looking closely I am trying to determine if the date code is 18 or 184. My car is an April 16 LA build, the 18 might be a bit early and the 184 is too late. Is this a service replacement?

https://hosting.photobucket.com/3d51...720&fit=bounds

https://hosting.photobucket.com/3d51...720&fit=bounds

https://hosting.photobucket.com/3d51...720&fit=bounds

What is the Julian date it should have bleeders

MC
 

Julian date is either 184 or 18 , see last photo.

The julian date is stamped on the machined surface where the brake lines screw in

I have had some with out bleeders a asked the same thing it may be for a automatic

The original 346, WT master cyl is still on my 1968 Z/28 that I've had for 50 years. It has bleeder screws & no date code.....Joe

There is no reason to believe manual/automatic masters were different. Both show code CU in box #56 on the Body Broadcast Copy.

Vintage road test photos (PHR March '69) show automatics with bleeders.

From JM’s 67/68 Z28 book confirming 5460346 WT master with bleeders.

Other things I’ve noted regarding the 346 master are that there are 2 front styles for the WT stamp and that some masters have an upside down cast number.
I believe that both versions of the WT stamp are legitimate although beware that reproductions (or restamps) do exist as stated in Chick’s build thread.
I also believe that both versions of the casting number are legitimate. I do wonder if Defiance had more than 1 foundry and if that’s the reason for the different casting number orientation and stamp font?

If you’re also looking for a lid you’ll need one without a SAE stamp. There are reproduction lids out there but it’s easy to spot them since font and word spacing is different.

Nice looking master here. Perhaps still available.

https://www.yenko.net/forum/showthre...hlight=5460346

My understanding is the bleeders were due to the tilt of the MC, and was to eliminate any possible air that might get into the brake line.