Chet wrote:
Hi Guys!
I run a 1/8 scale live steam locomotive.
While testing the vacuum brakes on my tender, I blew out the diaphrams
that activate its brakes.
The original unit was used as a vacuum advance for old-time carburetors
and is now an endangered species.
Anybody have success making their own from scratch?
If so, would you be willing to share the process?
Thanks in advance,
Chet (engineer of ANCR Mogul #9401)


Holley carbs with vacuum secondaries used a bolt-on cast body with
replaceable diaphragm. Same unit for 50 years and counting. Get the body
off any old Holley 4-bbl, including the truck models. Easy to adapt
mounting, add a nipple for the vacuum port.
Diaphragms available at any store that sells speed parts.