I installed a hydro boost on my 1987 K5 4x4 blazer, I bought a new hydro boost and master cylinder for a 1985 GM 3500. Since i did not have a core the new unit was missing the pushrod, spring and retainer that actuates the master cylinder. I found these parts on amazon, however the push rod is approx. 4 inches long, if I install it at that length, it would preload or push my master cylinder in approx. 1 inch from its natural position. This does not seem right, I made up a new rod that would just contact the master cylinder but not apply any preload. Has anyone worked on this type of hydro boost system that could let me know what the rod length should be ?
Thank you

 

I don't know the correct length for the pushrod, but it should NOT push the piston in the master cylinder at all when you aren't pressing the brake pedal. If it does, it will block the fluid return port and cause pressure to build up in the system and lock your brakes.

 

That confirms how to set it up correctly, very helpful thank you