Posted by Clint Dixon on Tuesday, March 05, 2002 at 11:17AM :
In Reply to: pw carb questions posted by JD on Monday, March 04, 2002 at 11:40PM :
John,
In the "Carburetor Specifications' section of Form 4735H for the E7F1 carburetor, and Form 4799G for the E7S1 carburetor, the only difference shown between these two carburetors is in the diameter of the bore through the Accelerating Pump Intake Passage Ball Check Seat. The specifications for E7F1 lists the bore as: .115 to .120 inch (2.92 to 3.05 mm). The specifications for E7S1 lists the bore as: .107 to .112 inch (2.72 to 2.845 mm). If I remember correctly, this hole is bored into the Main Body itself rather than into an insert or removable plug set into the Main Body. The parts lists for both carburetors fail to list a part number for the main bodies. I assume the main bodies between the carburetors are one of the same casting and the Check Seats were simply bored to the specific size during manufacture.
The parts lists with each form do, however, have one part number differing between them. This part is the Body Flange And Governor Assembly (the integral velocity governor).
This part is listed as 1-587S for carburetor E7F1 and 1-657S for carburetor E7S1. Form 4718F covering the Carter Velocity Governor shows 1-587S for carburetor E7F1 as being Governor Unit Number 220-6. It also shows 1-657S for carburetor E7S1 as being governor Unit Number 220-8.
The two differences between 220-6 and 220-8 show as being the overall length of the Secondary Spring and the number of active coils in the Primary Spring as regulated by the position of the Primary Adjusting Screw. Secondary Spring length of 2-9/32 for 220-6 verses 2-13/64 for 220-8 and 15 active coils on the Primary Spring for 220-6 verses 14-3/4 active coils for 220-8.
Carburetors ET1, ET2, and ET4 use the integral fuel filter and are correct for Power-Wagons from 1946 to 1947 up to engine #T137-8218. E7F1 has a smaller main body and float and uses the remote glass bowl fuel filter that threads onto the male tappered pipe threads on the Seat of the Needle and Seat assembly. It was used from 1947 to 1949 on engines #T137-8219 through #T137-16489. E7S1 looks exactly like E7F1 and was used from 1949 through 1953 on engines #T137-16490 through #T137-30543. At this time the E7S1 was replaced by E7T1 and/or E7T2 which used the sandwich governor....unless, (UNLESS) the truck was ordered with the Variable Speed belt driven Mechanical Governor for use with the Rear PTO, in which case, trucks starting with engine #T137-30543 from 1953 through 1958 were equipped with old E7S1 in order to work properly in conjunction with the Mechanical Governor.
Information from the 1958 Carter Sales and Service Manual was supplemented with information from 1948, 1951, 1953, and 1956 Power-Wagon factory parts manuals which do not always agree on engine or serial numbers.
The E7F1 is correct for your truck but no one will probably ever know if you install an E7S1 in its place.
Clint