Thursday, December 12, 2013

Carburetor Rebuild, Part 1

With the alternator reassembled, the next item on the to-do list is the carburetor.  The Previous Owner (PO) indicated that the carb would need "adjustment or rebuild".  Vague....

Well, it turns out that carburetor rebuild kits are only about $35-40, and I like the idea of going through it completely, rather than wrestling with a carb in unknown condition.  Besides, it's mid-winter.  A carburetor rebuild can be done indoors, with time that would otherwise not be available to work on the car.

So, where to start?  Well, first of all, what do I even have?  The carb is stamped with markings identifying it as a Zenith Stromberg.  A little searching online turned up this image and accompanying text:
The Zenith Stromberg CD150 series fitted as stock to later North American market Spitfires. Not the best "performance" choice. Many of the subassemblies are not adjustable or rebuildable. Lots of attached hoses and fittings. Early ZS carbs were manual choke. Later ones used a water heated auto-choke. Also shown here is the giant air filter / thermostatic air control contrivance.  [Photo and text courtesy Bob Sykes, taken from his brief writeup on Spitfire carburetors on]
Yup, that's my carb, and that's definitely the unmistakeable "giant air filter / thermostatic air control contrivance" sitting in my trunk.  So I have the stock, but suboptimal, carb option on my car.  Not a huge surprise.  I was gratified to find that at least my Zenith has the earlier manual choke, rather than the much-maligned automatic thermal choke system. 

Should I replace it with one of the other carburetor options, say, twin SU carbs from an earlier Spitfire, or a Weber model?  Nah, those upgrades cost many hundreds, even thousands, of dollars.  Let's just get it running and see what we have, shall we?

With that in mind, I did a little looking around for instructions, parts, and so on for the Zenith Stromberg CD150 carburetor.  Here are some resources I found.
I pulled the carburetor off of the manifold during a "warm" 25-degree afternoon.  It's currently sitting inside, awaiting the rebuild kit and a little free time.  Stay tuned!

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