Saturday, February 23, 2008

You Can Tune A Carb But You Can't Tune A Fish

Ok, so the album was "tune a piano" but the comparision is still the same. If REO Speedwagon were not muscians but rather mechanics, my title would have probably prevailed. One of the many problems that Number 2 had was it's ability to start easily. Most folks would probably assume it needed plugs or wires, or possibly a timing adjustment. In listening to the prior owners description of the problem - very hard to start, rough idle until it warms up, black smoke (sometimes) - I quickly deduced the culprit was the carburetor. More specifically, the choke. Before I started to make any choke adjustments, I made sure the engine was cold, just like it would be when you would start it in the morning. It also helped that it was a cold day when I started my adjustments.

This is what I saw when I pulled off the air cleaner. The choke was completely closed. It was a wonder the car could start at all! Let's check the choke thermostat to see what kind of shape it is in.

Oldsmobile used an exhaust heated thermostat and this one looked like it had seen better days. Don't always judge a book by it's cover...

Removing the thermostat revealed that it was still in pretty good shape. Adjusting it properly would prove weather the bi-metal spring was still working.

With the t-stat back in place, adjust it lightly until the choke plate just closes on a standard pencil.

Here is a close-up of my "pencil gauge". Notice how high tech it is.

Now that the choke was adjusted properly and the t-stat cover retaining screws tight, it was time to start the engine. There are two idle adjustments to worry about. One is the fast idle adjustment. This is the the idle speed that the engine runs at when the choke is set.

 Here is the fast idle screw. With the choke set and the engine running, I adjusted it to the manufacture's specification.

Once the engine was warmed up and the choke was completely open, I adjusted the main idle screw to the manufacture's specification. The choke opening all the way was a good sign as it told me that the bi-metal spring was working properly.

Now that all the idles are good I wanted to take it one step further and adjust the air/fuel screws. There are a few different ways to adjust these. Most manuals will tell you to hook up a vacuum guage and adjust the screw until you achieve the highest and steadiest vacuum.

Even though I have a vacuum guage, I have been doing this long enough that I do it my own way. While adjusting each screw, I will listen to the engine idle and watch the engine. Watching the engine is crucial, because I can see when it starts to run rough, and I know to reverse the direction of the screw a little.

Another item worth noting is that before I dug in with the adjustments, I made sure there were no vacuum leaks, cracked vacuum hoses, etc. I also checked the carburetor mounting bolts to make sure they were tight. You will notice in one picture my professional vacuum line plug - the air cleaner stud! Hey, I use what works. For those who are wondering why I am bothering with a two barrel, I have two words for you: Gas Mileage. Nuff said!

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