Advanced AFC Q's and part throttle smoke
 

I've read every AFC tuning thread I could find on the site, and think I've got a pretty good handle on it, but I still haven't seen it described in depth enough to make me 100% comfortable. I'll lay out my understanding below and please tell me if I have it right!

1. The travel limit screw. This is the long screw under the cap at the back of the AFC. I gather that it limits the backward travel of the AFC foot. I've read a couple people saying they run theirs 3-4 turns in from being all the way backed out. This would make sense in order to give you maximum backward travel to the foot, which is esp. useful when you have an AFC housing that is pushed all the way forward.

2. The position of the AFC housing. This sets the maximum forward travel of the AFC foot. This is necessary when you have a custom plate, and/or a plate pushed all the way forward. If the AFC housing isn't pushed all the way forward, the foot's maximum forward travel might be less than your fuel plate which would limit your full throttle fueling.

3. The star-wheel. From the cut-aways and description, it looks like it sets the pre-load on the boost diaphram. The discussions on this seemed to place it in the same camp as sliding the whole AFC housing, but it seems to me like this would set the "boost-point" that the AFC foot would yield to the boost, rather than the position of the AFC foot.

I'm asking for clarification because I am still not quite happy with the settings on my truck (see sig). I was able to get low-boost smoke under control, but I sometimes have smoke at ~1/4 throttle, ~10psi boost. I am hoping that a more complete understanding of the AFC might help me and some other people out.

Also, if anyone has any experience with smoke on a setup similar to mine I'd like to hear what I should expect. If I bring the hammer down it runs like a raped-ape and boosts to over 30psi in a second or two and has moderate smoke. I am wondering if I might reduce smoke, but maintain maximum power by moving the fuel plate back a little from full forward.

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There is another forum, Dodge Cummins Diesel Forum. Go there, look under 2ed gen 94-98 Tech, open it, look for "Tuning up a P-7100 pump". In that post there is a long detailed description that has a lot of good info. It should answer a lot of your questions. Hope this helps.

That is just what I needed. There is a lot of detailed info over there along with excellent strategy for adjustment. Looks like I pretty much had it right. It is deffinately an important 3-way of adjustment between AFC position, star wheel, and the "smoke screw" at the back of the housing. There was also an excellent write-up on fine-tuning plate position. Thanks a lot for pointing me in the right direction.

what website is this at I googled it but couldnt find it

web page
 

I think that I went to yahoo. search> type in the web page and that is how I got there, saved to favorites. Read also the article on fuel plates
Good luck Jim

What is the web site? I only found www.dodgeforum.com??

Bill,

You are the MAN!!

This is where I went...and not just that thread but the rest of the 12V area. I found these forum threads much more in-depth than the write-up on cumminsdatabase. Look for the posts by "got...DIESEL?", he's spent some SERIOUS time inside the P7100 and does an excellent job of walking you through it.