Jeep Carburetor Identification

WWII Carter Model WO 539 vs Post War Carter Model WO 636SA

This information was researched via internet resources and the best jeep web site on the net, www.g503.com. On the g503.com web site there are some very knowledgeable people providing very valuable advice, and have access to original, still in wrapper WWII jeep parts. The carb comparison is basically a rehash of the discussions, with pictures. If any part of this page is incorrect PLEASE contact me at farber@42gpw.com.

WWII production jeeps came equipped with a Carter WO model 539 carburetor. Carter also produced a post war Carter WO model, the 636SA. But neither have any useful identifying marks. The numbers on the fuel bowl are just part numbers for the fuel bowl.. not the carb itself. Also the inner workings are identical. Both carbs use the exact same rebuild kit. The only sure fire way to know that you have a correct 539 is if you have the original brass data tag (this was a simple brass tag affixed to the carb through a bolt) *somewhere* on the carb... sometimes the fuel bowl.. sometimes the mounting bolts... wherever the mechanic servicing the carb decided to put it (if at all).

One external identification is a subtle difference in the throttle shaft linkages, and possible the choke cable linkage. But these are external parts that can be easily changed. The Krager rebuild kit (the most complete kit available) includes a new linkage.
This is a picture of the WO 636(right) and 539(left). Externally the carb bodies look identical. Some minor linkage differences will be pointed out. Thanks to Mr. R. Adams for the pic.

Here's a blow up of the left side throttle linkages. This is where the accelerator pedal would connect. The 636 has long, vertical linkage directly in front of the brass guide. The 539 has a V type linkage. Also note the rear linkage. The 636 is a oblong shape, the 539 is 1 piece or V shaped... pic is not very clear... but they are different.

First is the choke linkage. The 636 (right) has two prongs, the 539 (left) has a solid choke cable attachment.

One of the most noticeable external difference. The throttle shaft linkage near the right fender on a 636 has an 'extra' ball linkage. This is for a remote throttle or governor depending on the 636 application.

Here are the two linkages side by side. The 'correct' 539 is on the right, the post war 636 is on the left. The ball linkage and extra arm are clearly visible.

Here is my 636 with the 'correct' 539 linkage installed. The 636 linkage is next to it.

636 has I-458 stamped onto the lower throttle casting. Also the 636 has screw holes and a machined surface for the 3 part linkage on the left side of the throttle shaft. The 636 lower casting is totally incompatible with the 539 lower casting. I purchased the 539 throttle shaft and it simply will not fit the machined area around the throttle shaft hole. the casting number is also significant. The I-458 is pointed out specifically in several Carter manuals. The 539 casting had a different number.


If you were to purchase a rebuilt carb from one of the excellent vendors available, you might be lucky enough to specify that you want a 539.

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