johnsjas

Whats this I hear about a rack travel mod. What is it and how do you do it? I also heard about changing a plug in front of the P7100 pump? I just installed a FASS system and have a race on Friday and I want to get into the 11's so any little bit will help.

Thanks

mainer

plug on the front of the pump. its 1 3/16" i believe and you can add a washer in there to give the pump more rack travel. to do this you need to grind a slight notch in the timing case so u can push the plug to thread it back in.

they make a "mack" plug which does the same thing, but you have to pull the pump to put it in.

i'm sure someone elsee will post pics.

johnsjas

Will this help if I am running a 0 plate (all the way forward) or am I maxing the pump out already?

kawi600

It should add about 30hp AFAIK

johnsjas

What is AFAIK?

thebestofindica

As Far As I Know

Muddin_dude06

What pump do you have on your truck? on my 215 pump and a Crazy man's #100 after adding 2.2mm of rack travel I gained a good kick in the SOP dyno and smoke was increased, it also caused my truck to gain 12-14 PSI of boost even with the wastegate set. You can use a piece of copper wire wrapped around the plug and just put a dab of RTV where the ends butt together, then you don't have to screw around with trying to get the plug to thread back in.

satburn

You say you did that on your 215 pump? Do you have stock plungers? Was this mod done at the same time you put a #100 plate in? I'm just curious because from what I've read and my own observations I would tend to think that this would hurt performance by blocking the fill port and shortening the fill time? I can understand it working on any of the other p-pumps since they don't have the same notch cut in the top of the plunger, but on the 215 if I send the rack out any farther I block the port.

johnsjas

I have a 160. Does the thickness of the washer/shim correspond directly to the increase in rack travel? Just to clarify its the plug in on the front of the engine by the fan right? The other question I have is if you can pull the plug out why do you need to grind the timing cover to replace it?

Sorry for all the dumb questions I just want to get it right before I mess something up.

Muddin_dude06

Yes sir I did it to my '96 with a 215 P-pump From all the searching and question asking I did I came to the conclusion that the stock front plug only allowed 15mm of total travel. Thats why I only added 2.2mm, because I have also read and been told that after 17mm of total rack travel is THEN when the pump would act up and retard the timing internally. Like I said I noticed a good SOP gain and more black smoke (thicker) and gained 12ish PSI of boost. My wastegate was set to 38PSI and the first time I got into it after modding the plug it blew right past the gate's setting and hit 50PSI. Needless to say I only did that once.


I also forgot to mention to modify your AFC "foot" so that the Gov. arm can ride on the plate only at full travel...
Yes however much thicker the washer is is how much EXTRA rack travel you gain, if you go more than 2mm or so I would advise you to put a "bushing" of equal thickness between the plug threads and the little plastic guide that resides in the pump, if you don't put that bushing in you run the risk of the rack coming out of its guide and causing a very big problem lol.

johnsjas

My AFC is empty so I dont think that I will have to do modify the foot.

Well from what I read I will add a 2mm shim and see how things go on Friday.

ratsun

First I just want to say I am not a expert on these pumps and I'm just speaking from personal experience not the he said or he did stuff.
Not to sure on the exact # for rack travel was on my pump as I didn't measure it but NW fuel injection told me around 16mm of travel is where you start to loose the initial timing that the 215 pumps put in? My personal experience with my pump was I cannot run with my 100+ plate full forward, however I did gain a little from a full forward without the plug. How many more mm I gained, I don't know? I will say that anyone that says it wont add more fuel on a 215hp pump has never actually tried it because I went from 60 psi 1200* too 75psi @ 1600* in one $6 move. So yes it did give me more fuel however I cannot use it. I may have got the same result by pulling the plate out and not using it for a stop but I never tried that? Since my pump was off, for $6 I put it in and played. As Muddin_dude06 stated I would be very careful with adding washers, I know someone that had problems with the rack falling out of the cap because it was shimmed out to far.