70c10 Brake woes!

I have a 1970 c10 that I have been struggling with the brakes for some time. The truck has been upgraded to front disc brakes by a po. I believed that the disc brake conversion was completed by using the 1972 c10 disc brake components. I have been attempting to change the master cylinder and have asked at a variety of parts suppliers for a 72 master cylinder for power disc brakes. The problem I am having is that the master cyl. I am replacing has a very shallow dimple for the brake booster push rod, all the parts suppliers have shown me have a deep push rod hole. I have learned that there were two boosters used on these trucks, one being a Bendix booster that uses a long push rod and the other a Delco Moraine that has a short or shallow pushrod. My booster is a Delco Moraine unit and the old master has a shallow dimple for the pushrod. Can anyone suggest a supplier that could provide me the proper part? I have been to all the chain stores and online also. I did purchase a master with a shallow dimple from Summit but I believe it to be faulty. Any ideas?

 

Take a look at a napa m2072, for a 73 c10. Should have the small dimple. Believe dimensions and threads are all the same as 71-72 but it should go down to a 1 inch bore possibly.

 

Thank you, I am going to NAPA in the morning to check on one I had ordered. The salesman called today to tell me it was in but he didn't think it was going to work.

 

Hopefully it works for you. Should span 73-80s on the trucks, 70-later one some cars. But it's the 5.5ish rod compared to the 8-ish inch rod you're probably running into.

 

I checked online and the photos look very promising. I have a more positive outlook than I have for a long time. Looking forward to a visit to NAPA in the morning.

 

Could you switch the pushrod?

 

Here are a few options for inserts that take up the space when using a non-power master on a power booster. A few aftermarket masters even come with these in the box.

https://www.summitracing.com/search/part-type/master-cylinder-pushrod-adapters

 

I suppose I could. The part suggested by JohnLewis appears to be the correct part and surprise it was on the shelf at the local NAPA.

 

I have been told that some master cylinders come with these but I have not found any with the adapter in the box. Thanks for the tip, it is good to know these are available.

 

A big tip of the hat to @JohnLewis, the master cylinder you suggested was a drop in. No modifications required. Thank you for the suggestion. Now I need to finish this thing up and get back on the road.

 

Happy it worked out for you. Look forward to some posts about the rest of your build.