Hi all, I’m working on a 50/50 air compressor.
It is a Buick 225 V-6, 3 cylinders pump air, and the other three run the engine. It is set up with a governor which controls a Rochester 2 bbl carb. The unit was, when new (in 1973) mounted as a stationary compressor in a farm tire service truck.
We have mounted it on a trailer to serve as a portable for outside sand blasting. The fellow I got it from told me it had been overhauled, but had then sat for a couple years (maybe as many as 10 or more?) Someone left it outside with no air cleaner during at least one rain…so it had to be torn down again, oil was pretty watered down!
Got the insides cleaned out, including carb, intake, etc.
Replaced or rebuilt everything that needed attention. Turns out it had been rebuilt, had new rings, inserts, etc, but the rings were stuck on the pistons.
Replaced the rings, and put it back together. Fired it up, it runs so-so, like it is out of time…runs okay for a short time, but spits and pops, including throwing fire back up thru the carb.
Took a guess that the rebuilder had it a tooth or so off?
Followed procedure in the service manual for resetting the timing, set all as per the book.
It runs a little better, but still, “sometimes” when starting, and after a load is put on it, fire still blows back thru the carb. I’m trying my best to understand what can cause this… seems like the only thing that would cause fire to come thru the carb, is a valve or valves opening at the wrong time, throwing hot exhaust gas into the intake, and out the carb, if so, and the timing is set correctly, then the timing really isn’t? Help! Rob
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