Engine/Transmission (1994 - 1998) AFC Spring

[RWorth]

After installing the #10 plate I put the stock AFC spring back in and with the star wheel adjusted to where there is no tension on the spring, it takes 34psi for full travel. I used regulated air to set the AFC position but had to go to 28 psi to keep the housing from full forward. I would like to have full fuel at about 25psi and adjust the AFC housing further back from full forward so that there would be more adjustment capability for the AFC housing. The medium spring from TST is to soft for the setting of 25psi. AFC would be to far to the rear of pump and probably would not allow for enough arm travel to allow the governor arm to travel the plate profile. I have the plate set approx. . 030 forward of center which is allowing about 32 lbs. of boost. Does anyone know where a person could find a spring that is some where in between the stock spring and the medium spring from TST, or how to rate springs?



Any suggestions?

 

[JPittinger]

I would think you could shim the softer spring to get a little closer to the spring constant you're looking for.

 

[BPonci]

There are a few mods you can do to allow you to be able to set your afc in any position and have full stroke of the arm. shimming the afc spring can in some cases prevent you to have full stroke due to a coil bind issue.

 

[Joseph Donnelly]

You may be confusing the light and medium TST springs. The medium spring should give a third of an inch travel at about 23 psi boost. The amount of travel needed is about 1/3 inch, and the spring rates are about these:

TST light spring: 38 lb/inch

160, 175, 180 hp pumps: 50 lb/inch

TST medium spring: 68 lb/inch

215 hp pump spring: 100 lb/inch

Moving the star wheel changes the spring tension at the start of travel and hence throughout the range of travel per psi of boost.

 

[Tom C]

RWorth,



Just last week while trying to diagnos a problem I tried some mods to the AFC. One was putting the meduim AFC spring in. I had to crank the star wheel 22 clicks towards the cab to get full travel at 25 PSI.



Diaphram washers were also reversed (Big lipped washer on the outside and thin washer on the inside) for more afc travel.