Ford mechanical fuel pump eccentrics
I recently ran into a problem with SB Ford fuel pump eccentrics that caused me to be towed home.
There are two versions of the Ford fuel pump actuating eccentric that may be bolted to the 'snout' of the camshaft. There is a very early version used on some 221 CID engines as well, but will not be discussed as I do not see much in the way of usage.
The first and most often seen is the one piece, cast iron eccentric. It is basically a foolproof piece of hardware. The second version is the two piece, Ford cost reduced stamped sheet metal version. These are not foolproof on an engine with anything more then an OEM camshaft.
I'll discuss the 2 piece version and why it's a poor idea for any engine with a performance camshaft.
This eccentric is bolted to the camshaft, but rests on the timing gear and is driven by a tab which extends into a hole in the timing gear. It's fairly light duty and can fail by having the tab ripped off, especially if you have a camshaft that has a less then smooth low end idle and fairly heavy valve springs. What happens after the tab breaks off is that the eccentric can revolve around the bolt, with the fuel pump arm not operating. This - based on the author's recent history and subsequent research. The timing gear drive dowel pin is well recessed. This dowel pin is 1" long
The second and better version is the cast iron one piece eccentric. While it too is bolted to the camshaft in the same manner, resting on the timing gear, it is driven by a 5/16" alloy steel dowel pin that goes through the eccentric, the timing gear and into a hole in the camshaft. As a note, this dowel pin is also the driver for the top timing gear, so the material does need to be reasonably good. This dowel pin - OEM, is 1-3/8 long
The one piece eccentrics are available from several sources like Summit and Jegs as well as anywhere that sells the Ford performance parts. There are two versions available, one for 3/8" retaining bolts and the other for 7/16" and are in the $20 to $25 range.
The drive dowel pin was discontinued by Ford on August 25, 2010. Luckily McMaster Carr has an acceptable substitute but it might have to be shortened for some camshafts. This is the McMaster Carr part number 98381A587 and is 5/16 x 1-1/2, 20,000 lbs shear strength/Rockwell C47/ASME B18.8.2. This pin MIGHT need to be shortened by 1/8" as the 'official' size is 5/16 x 1-3/8". The determining factor is that the pin cannot project into the eccentric cavity - the retaining bolt washer must be flush with the inside of the eccentric. The author's Ford SVT 'E' camshaft needed the full 1-1/2" length.
A note, a good brand 5/16" drill bit shank could be used in an emergency only
The eccentric mounting bolt should be torqued to 45lb ft. I recommended that an ARP 255-1001 (3/8") bolt be installed dry, but with thread locker.
Since the harmonic balancer removed, this will need to be torqued to 90 lb ft when reinstalling.