SU HS2 Carburetor

A few weeks ago I removed the carburetor from the Morris to rebuild it. Progress has been slow, mostly because I had no idea what I was doing so I didn't want to get in a hurry and mess anything up.

I have been doing a lot of reading and it is starting to pay off. I am beginning to understand how it all works, including why the gas vaporizes in a carburetor. After reading many many different sets of instructions on how to adjust it, and they seem to differ wildly, I hope to get it all figured out soon.

Last night, I successfully got the jet centered. It took several attempts, but once I got it right, it was dead on. Tonight I installed the carburetor back on the manifold. (I haven't hooked the throttle or choke cables yet.) After getting it mounted, I gave it a shot of starter fluid and attempted to turn the motor over. Unfortunately the battery was dead so after hooking up the charger I hit the starter switch again. It cranked up (and ran very smoothly) until all the starter fluid burned off. Two more attempts at cranking it before the bowl finally filled with fuel and the car started running off gasoline. I was fairly impressed with my efforts at this point because it was probably running smoother than I have ever heard it.

Tomorrow I plan to get back out to the garage and adjust the fuel mixture, idle, and fast idle. Hopefully it will all come together without much trouble.

(Dirty carburetor, before cleaning.)

Did you know that the reason fuel atomizes in a carburetor, is that when air passes through a venturi, the air speed increases thus causing the atmospheric pressure to decrease. (This decrease relative to atmospheric pressure is a slight vacuum.) The decrease in air pressure lowers the boiling point of the gasoline. The lower boiling power causes the gas to vaporize. Any extra fuel that does not vaporize at this point, will vapor due to the heat as it flows through the intake manifold.

My daughter would say this was "very interesting." This of course would mean she was not really listening.