Well, I have been reading everything I can on adjusting the plate and AFC. I went out and made some adjustments, trying to make it better. My truck has an awful bog starting out and belches black smoke, then when the boost builds, it goes pretty good. I was trying to fix the bog. I pulled the AFC housing off. I have a #8 plate on it and it was set about 3/4 of the way to the rear. I bumped the plate forward to where the screws are about halfway in between the holes. I then put the AFC housing on, and proceeded to strip the screw in the upper left corner This can't be good. I worked on trying to get a bolt just a thread or two longer to try to catch some good threads without busting out the bottom. I think I got that. I put everything back together and adjusted the AFC about halfway on the slides, with the AFC starwheel about halfway in the housing. Now, I still get a bog, but at least I don't have the coal train black smoke on start off. Once it builds about 6 PSI, about 3 seconds, it takes off to the point it can't be good on the tires It builds on up to about 1100 EGT with around 28-30 Lbs of boost. That is without a load, but it has never gone over 1150 preturbo. It pulls good up to about 85, I don't really want to go any faster. My dissatisfaction is not with the boost power, but with the pre boost bogging. Is there anything that can be done without a lot of smoke? I have a 91 that will jump this one big time out of the hole.
Thanks,
Chris

 

6 psi is where the fuel plate takes over. Sounds like you have it nailed. Below 6 psi the AFC housing position controls fuel. If you adjust it forward you get more fuel, and black smoke until the turbo catches up with the fuel. Adjust it backward and it's a dog. Your cross to bear for having such a great engine, but you can play with the starwheel to get optimum. Your 3 second bog is better than most, but I think there are turbos that have less lag. Others can tell you about it, I don't know much.

 

Have you checked the governor lever? It may be hanging a bit.

I do see another reason in your signature, a GB converter. Dave's low stall converter is great for a Cummins, but it does tend to dog the engine a bit until you get into the boost range above 1,500 rpm.

The only cure is going to a looser converter and if you're like me, no f**** way.

edit
corrected rpm from 1,000

 

Thanks a lot for the reply guys, it makes me feel much better. Maybe I am just expecting it to jump to quick off the line. I did check the governor lever, that was the biggest reason to go into it again. I don't really want to change the turbo. I guess I'll just accept it then.
Fueling around, you're right I don't really remember the truck having such a bog until I put the TC in. Definitely not changing that, it is too good everywhere else.
Chris

 

Move that AFC housing full-forward!!! Then use the star wheel to fine tune your boost enrichment from there.....You will be losing some bottom end power no matter what you do if the AFC housing is not full-forward.

 

I experienced the same slower pickup after the GB triple disc was installed , first explanation I read that explains why. Thanks. I played around with the afc cover and the starwheel a bit to help but the truck was a bit quicker at the start before the GB , but your right it's too good everywhere else to worry about it.

 

I have had the AFC forward and could not get it to quit blowing black smoke. Now, on my 91, it is set what I call perfect. No bog, and a nice haze all the way through when hammered, reading 28 PSI and 1250*. It doesn't have the rush that the 97 does, but it is quicker off the line. With the AFC all the way forward, I have a bog and lots of smoke. I equate smoke with money going out the tail pipe with fuel at 2.50 and up.

I drove it to work this morning and was really pleased with the way it drove. It seems the EGT at cruising has dropped about 100* with better response above idle. The turbo seems to spool much faster also. Is this possible? I slid the fuel plate just about 1/16 to 1/8 " forward and actually dropped cruising EGT and get better turbo boost response. I just never figured such a minute adjustment would make such a difference, or is it just my imagination. I need to put it on the road to check mileage now I guess.
Chris