Datsun Roadster Forum-311s.org

I’m putting solex carbs on and apparently previous owner switched to a 510 master cylinder There isn’t enough clearance. Are there any alternatives to the super expensive original master cylinder?

Check sincitydatsuns.com, they make an aftermarket unit that is quite inexpensive.

One thing to watch out for is that the 510 cylinder uses metric threads on the hydraulic lines & the roadster uses SAE. They will screw in but not seal well.

Peace,
Pat

I've had three different kinds of sidedrafts... Mikuni, SK Racing, OER (and now Jenvey throttle bodies that mimic Webers) all with the 510 master without problems that I recall. However, I'm not above removing or modifying something to make it fit, so it's possible I removed or moved some things around on the carbs... it's been too many years. What's causing the interference? Maybe there's a work around...

Something is wrong the 510 master should work fine with the Mikuni’s. Maybe post a picture of the problem area and that would bring out what the root of problem might be.
Dave

pic attached

i think I saw something on here about different versions of the 510 master cylinder being sold by rock auto and the spacing between the front and rear reservoir being different.

Ya, I think my 510 master is different but it's not easy for me to go look... still on crutches from the car accident! I'll see if I have any pics that show...

That is the wrong 510 master cylinder. The early 510 master from 68 to 73 is different than what I see in the picture. I suspect that is the later 510 master cylinder. Which was a completely different chassis than the original PL510. So change the master cylinder and everything should work. Nice that your Mikuni’s are the type 4 Nissan roadster version.
Dave

I just looked and verified the master cylinder you have is a 510 aftermarket cylinder. If you go to the vendor section and look at new Datsun parts website and then look at the 510 master cylinders he shows in that section, you’ll see the difference between the original and the aftermarket ones.
Dave