The Stovebolt Site Forums The Parking Lot Big Bolts perplexing 409 update

I thought I'd update my lack of success getting the 409 in my C-80 to run. In our last episode, I had taken the starter off cause I thought it was getting weak. Had it rebuilt but it's still weak, guess it's the battery, even though it shows 12.5 volts and passes load test. It cranks OK with the charger on it. Yesterday I pulled all the plugs and did a compression check. All cylinders except 1 had 125-130 lbs. #4 had 95, so I don't think a valve or stuck ring is my problem. While it was all open, I checked the timing by turning the #1 to TDC. Everything is right on the money. The points are set to .019", just like my old motors truck manual calls for. I have a healthy spark at all the plugs, but I cleaned them any way.
As long as I squirt gas in the carb, it'll run but won't idle. All the lines have been cleaned/ replaced from the sender inside the tank, to the new fuel pump. The filter now stays full, so I know gas is getting to the carb. I can't swap carbs to try it out because the intake has the very small pattern for the 4GC. I saw that Show Cars has a new adapter to put a later carb on these intakes, I may have to order one of them. Only problem is then my big 'ol cool air cleaner won't fit the large neck later carb.

It looks like you have some crud in the idle system on your carburetor. Nothing short of a rebuild is going to help, although there's one trick you might try first. Get the engine running at a pretty good speed, 2,000 RPM or so, and either close the choke plate completely, or slap a big piece of rag over the top. This allows the manifold vacuum to suck liquid gas through all the passages in the carb, and sometimes it will flush minor deposits out. Several of these maneuvers will clear things out at times, but don't count on it.

Send an IM to Carb King here on the site. He runs a very good carburetor rebuild shop, and he can probably rebuild the one you've got (best choice) or sell you a quality reman carb. Swapping to a newer carb or just dropping any old 4GC on it would be a terrible idea. The 409 was a pretty limited production run, and the chance of another type or part number carb being right is slim to none.
Jerry

The 4GC was produced for about 15 years. They were very servicable and parts are still available. Back in the 60's it was very common to replace the 409 4GC with an Olds, or Cadillac carb to get rid of the velocity governor.