Tom, the owner of TM Tractor Parts and one of our sponsors, recently asked me to evaluate the new reproduction Cub carburetor that has recently come on the market. He also requested that I attempt to install a CaseIH rebuild kit, CaseIH idle tube and replacement IH float in the carburetor to determine whether the parts are compatible with the new carburetor. The following comments are the results of that evaluation.
In general, I feel the manufacturing quality of the reproduction carburetor is excellent. In fact some of the parts, namely the float, is of a better quality than the replacement part. The metal from which the reproduction carburetor is manufactured â€œseemsâ€ to be harder than the originals. Hopefully, this will reduce some of the throttle body warpage frequently experienced. In disassembling it, several major differences between the reproduction carburetor and the original carburetors were discovered. The photo below shows an overall view of the reproduction carburetor as it comes out of the box.
All of the gaskets on the reproduction carburetor seem to be thinner than their counterparts in the rebuild kit. Notice the fuel bowl gasket in the above photo.
The float needle valve cage assembly is a totally different design than the original. The reproduction carburetor needle has a rubber or neoprene tip. The replacement cage assembly from the rebuild kit did fit properly. Because of the lesser quality of the replacement float, it did require a lot of tweaking to make it fit and work properly. The cage seat area in the reproduction throttle body casting is several thousandths taller than on an original casting, but that didn't seem to be an issue. The difference is visible, however. A photo of the cage and needle is shown below.
The idle tube in the reproduction carburetor is about 1/4 inch shorter than the original/replacement. Also, the inside diameter of the idle tube on the lower end is larger on the reproduction carburetor. The reproduction carburetor bowl casting is machined to accept this shorter tube. Therefore, a CaseIH original/replacement idle tube will not fit in the reproduction carburetor. The consensus following discussions with Tom and other forum members, is that it may be possible to shorten the replacement tube and make it work. Further research will need to be done. The photo below compares the two idle tubes. The reproduction is on the left, the CaseIH replacement on the right.
The orifice in original/replacement main metering jets is .032 or .034, depending on part number. The orifice in the reproduction carburetor main metering jet is .040. It was not obvious whether other internal parts of the reproduction carburetor may have been modified to accommodate this difference.
I replaced the reproduction throttle shaft with the CaseIH replacement. There didn't seem to be any issues there. I did not replace the felt seals and retainers for the shafts, but it seems like that wouldn't be an issue, either. The drip hole felt retainer on the reproduction carburetor is different than the CaseIH replacement, but it doesn't look like that would preclude it from working. The replacement may require staking, whereas the reproduction does not. The idle adjusting screw and spring exchanged with no problem.
Tom replaced the original carburetor on one of his Cubs with the actual reproduction carburetor that I evaluated, prior to sending it to me. He made no modifications to it, including no adjustments to the float or idle screw. He said it started on the first try and ran normally.
In conclusion, I think the reproduction carburetor is an outstanding product and will adequately fill the need for a reasonably priced replacement carburetor for those not looking for strict originality on their Cub. The fit and finish is excellent and with a very slight amount of modification, the replacement parts available will enable buyers to keep it well maintained.