I found a remanufactured carburetor for Ol Blue, still in the severely degraded cardboard box, which had been sitting on a parts house shelf since the '70s.The Rochester B and BV carbs are getting really old, parts and specifically non warped or completely non-junk parts are hard to find, so I jumped on it.
Near as I could tell from the main jet size, it was setup for a 4 cylinder early Chevy II. Ya, GM had one. Didn't sell many.
So. I re-jetted it for a 250 6 banger at sea level and bolted it on. It worked OK, but occasionally, on cold days, experienced a cold engine hesitation I couldn't figure out.
Today, after running out of ideas, I finally figured out the issue.
There are two types of vacuum ports on a carb, manifold and ported. Since the vacuum port I connected the spark advance to was in the exact same spot on as the old junk carb, a ASSUMED it was ported and just ran it. Nope.
This 4 cylinder carb, lucky for me, has another, blocked off port in a different location that's actually ported. So I setup a new port. The JB Weld is drying as we speak.
This is the kind of shit that makes non-technical people sell old cars. Luckily, I'm here to take the un-fixable junk off their hands for a good price. :ohyeah:
:clap:
I had to read this (https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/34918/ported-vacuum-and-other-myths.html) to figure out what you were talking about. :confused: