Made in both 40mm and 44mm sizes. The 44mm version can be known as an "early" PHH44.
These tops use four bolts to hold them on and another is used for the jet cover.
This type cannot use the Main Cover Gasket from the S5. From my experience of rebuilding the two it is a fact, the two front side screw locations do not align. The S4 and S5 Main Covers cannot be interchanged sucessfully to gaurentee a good seal or alignment of those screws.
This is a typical OEM fuel inlet arrangement and is without the external float adjustment. Some versions used on the Nissan/Datsun use a side entry. Both use the same fuel pipes and filter screens as the S5, T/R and PHH44
The S4 main body. This body does not have the same bolt pattern across the four similarly located S5 bolts. The S4 and S5 Main Covers are not interchangeable.
RM Carburetors: Copyright 2015
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