Hey guys,

Anybody know the standard master cylinder bore size that was on '73 240s?

R

I believe they are 7/8 inch.

Yes it is 7/8ths and it is probably stamped on the side of the master cylinder casting. The stamp should be on drivers left near the base of the master cylinder where it mounts to the vacuum booster. So if you open the inspection lid on the drivers side you should be able to see it. Might need a mirror and a flashlight if your eyes are a little worn but the numbers are fairly large.

Have fun!

Thanks guys you were spot on : )