Only Aftermarket stuff like those from Bear and Wilwood are truly (or should I say
intended to be) adjustable. All the "OEM booster pushrods" come pre-set from the factory/remanufacturer. ...at least that's what I was told when I had this issue with my Corvette. What they told me: You probably have the wrong Booster or Master.
Are you sure it's not adjustable? I had to pull the pushrod out of the booster a bit to be able to see that the tip of the rod was actually a nut. Unable to locate a pushrod measuring tool locally, and unwilling to wait, I turned it out 4 or 6 turns and went from a brake pedal that engaged less than 1" off the floor to a pedal that engages at the top of the stroke. A little bit goes a long way on this adjustment
When I got my 'vette, previous owner stated "the brakes are a little soft, I think I was sent the wrong master or I need to buy longer pushrods.". It didn't take me long to figure out that the booster pushrod measuring tool wasn't available locally because OEM and OEM replacement boosters come "pre-adjusted". ...that said, mine had an adjustment. They come pre-adjusted from the factory after all.
wink-wink
Really don't know what to say other than what I was told, and that's "these are not adjustable", but, that was 100% BS in my case. Pull the rod out of the booster a little if you haven't and inspect the tip. Hopefully, the rounded end of the bind-nut is throwing you off. I did me for a minute. Also, careful with the "Shade Tree Mechanic" fix on this one. There's only a few thousandths tolerance allowed between the rod and cylinder. Not enough, pedal engagement is grossly affected. Three thousandths too much and the brakes will drag when the system heats up. We really should have the measuring tool to set the booster pushrod properly. All the performance brake companies, Summit Racing / Jegs, sells them. Price goes from $20 to $80. I personally wouldn't buy from Amazon, but, this is one of those things that's probably safe assuming the seller isn't a scammer. Buyer Beware as they say. I think the Summit or Jegs tool is around the price of this Amazon one, and I'd recommend purchasing from them instead.
Good Luck!
Edit: Just remembered... When searching for this tool, I came across an image at a sellers website that included enough dimensions to build your own. If you're interested, I saved it and should be able to dig it up without too much effort; or you can search around for the same image. I went the shade tree mechanic route. Figured I'd turn it out a little and see how it affected the pedal. After just a couple turns, the pedal engaged where my brain thought it should engage. To be honest, I should probably back it off 1 turn. The tool is important. At the very least, it eliminates all guessing. If you go this route, check for dragging brakes after the test ride and everything is hot.
