The shriek under the hood was a little harder to track down than I expected. I first suspected a vacuum leak in the stack of plates and gaskets under the carb, but an investigation turned up nothing. Then I thought that perhaps the increased height of the carb with the new spacer was binding up the throttle linkage. (The noise did have a kind of metal-to-metal component to it.) There was a bind, but it was minor and not the cause of the shriek..

Spacer Coming Out
Removing the spacer. Need to find one that matches the four ports on the manifold.

I finally broke down and removed the heat-isolating spacer and the noise went away with it. (I’m getting really good at pulling and replacing the carb.) I don’t know for sure why that plate was causing the noise, but I have a suspicion. The four barrels of the carburetor match up with four corresponding holes on the manifold. The spacer has a single opening, which must interrupt the airflow from the carb into the manifold somehow, causing the shriek. I still think a heat isolating spacer is necessary, (I’m already noticing more difficult hot starts) but I will have to find one better matched.

Underhood Cleaning
Underside of the hood, half clean, half to go.

The silver lining here was in tracing back the throttle linkage. Not only did I correct that small  bind, I also discovered that fully depressing the accelerator was not opening the throttle all the way. I reworked the linkage and found a little extra power (not to mention a more positive response to the choke).

Last item for the weekend was a little more clean up under the hood. I haven’t noticed any leaks since replacing the water pump and restoring the valve covers, so I wrapped the motor in old towels and took some degreaser to the inner fenders and the underside of the hood (which was really a mess.) Nice to open the hood see some sparkle in there.

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