BenzWorld UNIMOG statesman
Unimog 404.1 Diesel (sold :( )1995 LMTV 1078
This is info on reflection of a mystery holley carb being sold on Ebay for Mog 404's. Thought it would be good info for someone to research further. Will help out lots of folks.
Repeat from Mail list
Hello to all,
Personally, I am very curious about this Holley carburetor conversion. It appears to be most likely a Model 2280 or Model 6280.
Unfortunately, none of my three Holley reference books list the CFM values for these carburetors. I have asked the seller for this information. While I may not need to know the model of the carburetor, I certainly would want to know its CFM rating before I would spend a dime on a carburetor. According to the following source, the 2280 and 6280 carbs were used on engines from 3.9 liter to 5.2 liter displacement.
yet the following site lists 2280 CFM anywhere from 184-340 CFM.
Ideal flow rate for a stock M180 engine is around 194 CFM with 100% volumetric efficiency. Realistic flow rate may be as low as 146 CFM. The Haynes Techbook #2069 does have a nine page chapter in the 2280/6280 carburetor series including exploded diagrams. These carburetors have many of the features that make the Zenith 32NDIX so popular as well as some improvements including a very nice float bowl baffle.
I have looked at the eBay photos and know that the carburetor in question is not the Holley 2110 Bug Spray of old. For an example of the old Bug Spray, take a look at:
For those interested, the Bug Spray was Holley's answer to the early VW off-roaders use of the Zenith 32 NDIX. The bug/buggy drivers were not aware of the use of the same carburetor on the Unimog 404. Rather, this was a carburetor used on the early Porsche 356 cars in a dual carburetor configuration and was better the little Solex single barrel carburetors. Porsche used a pair of Solex carburetors on later 356 cars because they were thought to be.better. Carter also produced a Zenith 32 NDIX alternative. The Bug Spray was available in both 200 and 300 CFM versions. The air horn and base share the exact same dimensions as the 32NDIX.
There is nothing significantly wrong with the stock Zenith 32NDIX but it is not perfect. In 1955, it was the best off-road carburetor available to easily fit the intake/exhaust manifold borrowed from the MB 219 sedan with its very early M180 motor running a single two barrel Solex PAATJ carburetor. But one must admit that, if the 32NDIX was "perfect", it would not have
faded from the general off road scene so long ago. Even AutoUnion/DKW further modified their Zenith 32NDIX on the MUNGA by extending the float camber vent 2" above the upper edge of the air horn.
That small vent tube screws directly into the threaded bung in the vent crossbar and prevented spillage of gasoline through the vent and less
radical angles. Imagine that: an improvement on the "perfect" carburetor that was never included on the Unimog. My biggest disappointment with the stock 404 carburetor was its constant leakage. Having gone through several used and no less than three NOS carburetors from two separate very reputable dealers and using fresh gaskets, I grew tired of the frequent leaks. I recall a post on this list back around 1997 when someone advocated solving the constant weeping problem by spraying the entire external surface of the
Zenith with Varathane.
I would like to see something new for the 404 fuel delivery system just as I applaud the Pertronix in the standard 404 distributor, new tread patterns over the original NATO tires, and other product enhancements. I am certainly not sure the offering on eBay is the right way to go but it just might be.
We shall see. Take care.