With Wings As Eagles: Car/Mechanical Entries

Continued Carburetor Work

2012 April 17 09:10

I got a bunch of carburetor work done this weekend. I installed a 34PICT-4 in my vintage Beetle and ran it on Sunday. I realized on Saturday that I'd put in the throttle plate upside-down, so Sunday I fixed that. The carb's not running right, but perhaps good enough to be an on-the-road spare. Later Sunday I spent time deciding if I could resurrect one of the other 34PICT-4s that I have to replace it.

A quick illustration so that people can see what I'm on about. Here are two carburetors, a 34PICT-3 on the right (that's the most common carburetor for the dual-port aircooled engine), and the 34PICT-4 (one-year-only California spec carb) on the left.

You're looking at the left side of each carburetor. The forward part of each carb (to the left in the picture) is the float bowl, where the gasoline sits. The 34PICT-4 on the left has the thermostatic valve circled, and an arrow points to the corresponding point on the right.

Pangur feels about the same way as most mechanics about carburetor work.

Here's the engine running with the 34PICT-4 on Sunday.

You can just barely see the tell-tale brass plug that is the external part of the thermostatic valve.

I've spent a lot of time digging up test equipment to use on my vintage Beetle. It turns out that there's a modern tool that has the tachometer and dwell functions and ALSO is a timing light. It's an Equus 5568 timing light, but it has all the other functions built-in. Here's mine in use:

I'm trying to rehabilitate a couple of the old 34PICT-4 carbs that I've bought. I tried running them through the dishwasher; that cleaned them up a bit, but not dramatically.

The problem with all the carburetor's I've had to some degree is that air leaks into the carburetor around the throttle shaft. This messes up the fuel-air metering and makes the idle unstable and difficult (or impossible) to adjust. The 34PICT-3 that is currently my one good carb has had its bushings replaced. I had the 34PICT-4 that I'm attempting to use re-bushed as well, but perhaps it wasnt' done correctly, or something went wrong.

So what I'm doing now is I'm cleaning up one of the used 34PICT-4 carbs I have and I'm going to see if I can re-bush it myself. Long ago I bought a set of solid brass throttle shaft bushings from someone in England who had some. I'm goin to try installing them into the best 34PICT-4 that I'm cleaning up. Here's a pic of dry-fitting the bushing into the throttle bore.

So hopefully next weekend I'll see how much of a difference I can make with that.