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Rack Travel

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Just some useful information that maybe an insight to a few wondering minds. All results were taken from a 160hp(838) P7100 using a stock 180hp(885) profile plate. Max rack travel is 21mm with a range of 12mm off idle. Note that the 2095 rack plug adds 2mm over the stock 2000 rack plug. The max protrusion of the rack external of the case is 8.5mm, max recession is 12.5mm, and a recession of 4mm at idle. The designations will be 0% = full rearward, 50% = mid position, and 100% = full forward.

Stock Plate

0% - 10.5mm

50% - 14mm

100% - 16.5mm

#0 Plate

0% - 18mm

50% - 20.5mm

100% - 21mm

Also I have comparison information of the rack travel allowments of a stock AFC and an AFC in which the diaphragm washers have been exchanged. The designations will be 0% = full rearward and 100% = full forward. These results were taken with no plate installed to allow for governor lever contact with the AFC lever.


0% - 19mm

100% - 20.5mm


0% - 20.5mm

100% - 20.5mm

Here are some pictures of adjustments you can make to achieve full rack travel by modifying the AFC washers and lever. I loosen the tension from the pre-boost fuel screw to lessen smoke before manifold pressure is built, use this to your personal preference as with the starwheel tension. One modification is to remove the diaphragm from the rear of the AFC housing, there are washers on both sides, you need to exchange them so the shallow washer now rests on the AFC spring. However this modification will not allow full rack travel, so you may also grind the leading edge of the AFC lever flat removing roughly 1/16-1/8" to achieve desired results.

Modified washer method is on the left


Modified lever is on the left


Modified lever is on the top


Pre-boost fuel adjustment screw


Starwheel adjustment port


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These results will help give a measurement to adding rack travel for performance purposes, also they should help to take some of the guess work out of tuning, which is my goal. These results will dispell some myths and verify these truths.

1. A #0 plate full forward is equal to no plate

2. Switching the washers of the AFC will not provide full rack travel

3. The 2095 is detrimental to performance in the 887 and 913 P7100

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Guest 9812VCTD

Thanks for the info when I get my stumble issue resolved I plan on taking some time and doing these mods to the AFC. I'm sure I'll have questions for you when I get going on it.


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I'm not positive this is the correct answer, but i think the 2095 rack plug is detrimental to performance in both the 887 and 913 pumps because it allows the rack to travel to far, thus over rotating the fuel delivery barrels.

If thats not right i am sure smokem know the answer.

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