Just wanted to get back to you guys and let you know what I found and what I did to correct the problem. (See Images) Problem was actually in two places. #1 What I will call the UNDER CAB DIST BOX. This is a mechanical over diaphragm operated box that is controlled by the two speed button on the shifter. #2 The VACUUM OPERATED TWO SPEED CONTROLLER mounted at the rear axle.
Once I pulled the UNDER CAB BOX apart it was mostly gummed up. After cleaning it seemed to operate fine on a test bench so I re-installed it but still had a similar issue. Next I went to the rear TWO SPEED CONTROLLER and took it apart. Inside was also heavily gummed up plus a hole in the diaphragm. I finally found this diaphragm on ebay through Rebuilders Interprises. Part #GM#3847058 BENDIX#374451. About $30 Shipped.
PROBLEM HAS NOW BEEN CORRECTED.
Below I will just go ahead and do a copy and paste of the file I am building on this project. It may help others. Since I am not done with this project some of it may turn out to be invalid but here it is anyway. Thanks Guys - Much Appreciated!
******************************************************* 1967 Chevrolet C50 Grain Truck 327 Small Block V8 - 4 Speed Trans - 2 Speed Rear Axle - 14.5' Knapheid Bed - Anthony Lift - Original underhood items like Air Cleaner - Govenor'd Carb (Disconnected) Distributor - Firewall Mounted Vacuum Booster. VIN CE537J141691 - Mileage 58,173 (4/15/23) Engine: Fuel Pump M6624 - Dist Cap DR429T - Condenser DR70T - Points DR22780PT - Carb - Autoline C945 - OEM Part Numbers 7013353, 7015019, 7020109, R22G Rochester 2 Barrel;
Distributor Delco Remy 1112796
Paint Color: THECOATINGSTORE.com Habenero V-Belts Water Pump/Alternator 17560DR 56017DR x 2 Bendix 2501422 GM# 3959747 2 SPEED REAR AXLE DIAPHRAGM GM#3847058 BENDIX#374451 Eaton 47638 takes a GM 2398285. Bendix 374451 which takes a 3847058 GM Transmission - Muncie P21XC (M21) REMOVING THE GOVERNOR OFF CARB: On the passenger side of the carb is a diaphragm assembly. On the back side of diaphragm is a removable steel tube that goes into a T that enters the lower part of the distributor. Your distributor is mechanical advance so vacuum is not required. On the T you will find a wire attached to a spade terminal and solenoid. Additionally there is a small filter screwed in the side of the dist. These can be left in place if you want. This carb mounted diaphragm pulls constant (metered within distributor) vacuum. If you simply block that vacuum by removing the tube and plugging its entrance to the diaphragm then the motor will no longer rev up. Just forward of the diaphragm is a small flat plate held on by 4 screws. Remove this plate. Inside you will find a spring attached to a rod that goes up into the diaphragm. First remove the spring then the nut that holds on the "rotator". Now you can turn this by hand until you can line up the slots and remove it from the rod. Don't try to remove the rod from the diaphragm because the brass rod stays in place but it is now no longer affixed to the rotator plate. Put the small rotator plate back on and affix with the small nut and then re-attach the spring. Next make sure the rod is not binding up anywhere by hand throttling the carb. If everything looks free then go ahead and put the outer plate back on and you are done. For ease of removing the distributor or other wise working on it then it is advisable to remove the steel tube entirely and plug both the diaphragm and the Tee to prevent dirt from entering. Now you have accomplished two things: You have removed the governor and also removed what is mainly just a vacuum leak at the source.
