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Cranking Up the Fuel Screw on 85 6.9 IDI

  
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Cranking Up the Fuel Screw on 85 6.9 IDI

 
powersmoke85 powersmoke85
New User | Posts: 38 | Joined: 04/10
Posted: 04/22/10
03:02 PM

I have a 85 6.9, I dont have a turbo kit.. yet, maybe someday. but intell then I'm looking to add some ponies. right now i average over 20 mpg and love every second of it. but i am willing to sacrifice some of those miles for some more get it and go and more pulling power.
so my question is: how far can i turn up my fuel screw before i really start loosing millage??
how far is too far?, and many turns will make a differance??  

tdbt3c tdbt3c
User | Posts: 200 | Joined: 09/08
Posted: 04/25/10
10:02 AM

I assume you are familiar with where your injector pump is. Remove your throttle linkage at the pump. You should see a triangle shaped plate with two small screws holding it in place. Remove this plate (when you do, diesel will drain out of the pump and run down your valley cover, have a drip pan under the bellhousing to catch it).
Now you need to remove the cover plate on your oil fill neck. This will expose the front of your injector pump/timing gear. You should see three bolts and an alignment pin. Using a breaker bar on the harmonic balancer bolt turn the engine until the alignment pin it at top dead center (12 O'clock).
Going back to the side of the pump (with a mirror) you should be able to see a hole at the point of the traingle shaped hole. You should be able to reach in the hole with a 5/32 Allen wrench and turn the delivery screw up. Clockwise (facing from hole) will add fuel delivery.
Note that the screw turns very tight and is self locking. When I put the turbo on my '87 6.9 (Banks Sidewinder) the instructions said to turn it 1/4 turn. I don't know why, but I could not get it to turn much at all, and as a result the truck was running lean. However when we moved the turbo to my '88 7.3 we turned the screw all the way, as far as we could. I have not had a good chance to check the highway miles but it averages around 15 mpg. I did get over 17mpg once but that was driving about 45mph on the interstate.
Lemme know if you have problems. Good Luck.  
1988 F-250 7.3L w/Banks Sidewinder Turbo. Custom flat bed with hydraulic dump.

powersmoke85 powersmoke85
New User | Posts: 38 | Joined: 04/10
Posted: 04/25/10
09:23 PM

Thats what i was doing, just wasent sure how far to turn it. like i said i love my 22+ mpg, and my power is great too, but of curse.. there is no suck thing as too much power Smile. and right now a turbo kit is out of the question, this is just my work truck and farm toy. but ill just give it a little turn and see what she does, if its not enough or too much ill just adjust it some more.  

tdbt3c tdbt3c
User | Posts: 200 | Joined: 09/08
Posted: 04/27/10
07:29 AM

I must say, on my old 6.9 I don't know how much power I really gained through turning up the screw. It seemed like I just lost some mileage and blew a lot of horribly rich smelling exhaust. I did however notice some gain in that when I went from a stock to a K&N air filter.  
1988 F-250 7.3L w/Banks Sidewinder Turbo. Custom flat bed with hydraulic dump.

powersmoke85 powersmoke85
New User | Posts: 38 | Joined: 04/10
Posted: 04/27/10
10:49 AM

I have kinda droped the idea of turning it up because I love my millage right now and the power is plenty for what I use it for. I can pull 5000 ibs no problem. so thats good enough for me. but however like you said about the K&N, I did make my own "cold air intake" by taking off the air cleaner and making a PVC pipe (5 inch) rapped in heat tape and a cone filter on the end. and I did get a noticble amount of power and better throttle repsponce. I think letting these old dogs breath is a great way to add power, like most engines really. maybe some day I will be able to get a turbo!! Grin  

tdbt3c tdbt3c
User | Posts: 200 | Joined: 09/08
Posted: 04/27/10
11:03 AM

PVC!? Nice. So since you have already rigged it with PVC, why not do a little more rigging. You could build a phony supercharger for it. Find a small electric fan, like a computer fan that you could mount inside the PVC pipe and wire up through your fuse box. Just find a fan that is rated to only push around 5 psi and see what that does. Granted you will be getting 5 and only 5 psi, all the time, but what is the difference between that and a hood scoop running down the highway? Just mount a boost gauge to it to make sure you don't accidentally overdo it.
I think that would be interesting to see what it would do. Let me know if you try it, I would like to see the result.  
1988 F-250 7.3L w/Banks Sidewinder Turbo. Custom flat bed with hydraulic dump.

powersmoke85 powersmoke85
New User | Posts: 38 | Joined: 04/10
Posted: 04/28/10
09:44 AM

yep, good old PVC pipe, its cheap, easy to work with and comes in any shape and size Smile
thats funny you said that about the electric fan, I have read in car mags about people doing that to their little four cyl cars and trucks to have a "superchager". It had entered my mind to try rigging up a system like that for my truck, like you said it would be a consitent PSI but when your towing and need a little boost it would work great. My thoughts where also along the lines of using a small electric leaf blower, the kind that have a "throttle" on them to control how hard they blow. if I could find one like that and rig it up it might work pretty sweet, and with a PSI gauge in it to be sure i dont over do it. it might be a great cheap alternitive to a turbo. I guess we'll find out!  Grin  

tommyking tommyking
New User | Posts: 1 | Joined: 01/14
Posted: 01/30/14
07:37 AM

where did u end your homemade intake?? im deff gonna make one myself ive heard that the factory intakes can rust an let water into the engine== bad day... thanx I deffenetly plan on making mine asap