I have a friend who is a diesel mechanic and Cummins certified. We had made plans to adjust my valves and my timing. He is saying that instead of adjusting the timing we should adjust the screw on the back of the AFC housing. The rack stop I think. I could be wrong. Will I see any mileage improvement from the rack stop adjustment like I would from a timing adjustment? Is one better than the other, or are we taking the easy way out? Thanks in advance.

 

Do the valves and timing, sounds like he doesn't want to do much, the timing will get you the mileage, Goodluck,,Rick

 

Sounds like you need a new mechanic.

 

Some people just never get it.

Jim

 

txwelder- Before you act read the articles written by the owner of Diesel Injection Service of Pittsburgh: http://www.dieselinjection.net/frames.html Your mechanic is not sandbagging the issue, He is following Cummins procedures. DIS retards the timing on Cummins diesel engines when adding horsepower. Advancing the timing places extra stress on the bottom end of a diesel engine. Think about the sequence, the piston compression causes the fuel/air mixture to ignite from the heat of said compression. When the piston is still traveling up on the compression stroke and the timing is advanced beyond specs, the forces placed upon the rods, crankshaft, and all bearings are going to create excessive wear. I place my cherished CTD in the care of my local Cummins authorized repair center and don't try to out think the experts.

 

Well I was just curious because I see most people praising the timing adjustment and havnt seen much about the rack stop. This guy told me he had done it on a service truck that was having problems and that it made a big difference. I wasnt trying to outhink the guy, he is doing me a favor, I was just protecting my backside. Thanks for the info.

 

By adjusting the star wheel in the AFC housing you may decrease your milage a bit.
All you are doing by adjusting this is allowing more pre boost fueling.
It does not effect fueling after the boost is up.
So by doing this you will add fuel earlier.
And if you have a heavy foot you will see more smoke on take off and possibly less economy.
Like said before bumping up the timing above specs will get you HP and fuel economy.

And I think you may need a new mechanic.
Just because someone works for a company doesn't make them an expert.

: Eddie :

 

I think bumping up the timing or at least having it checked to see if it has retarded is one of the most important things that should be done to a 12v it makes such a big difference.

 

DIS of Pittsburgh is of course right, but their advice is for the big Cummins motors. The DC engines had very retarded timing to control certain pollutants to meet EPA standards. For example my CPL 1959 is 12.3*, whereas a higher power CTD in an industrial application may have 15*. As pointed out, there is a limit where more advance will cause damage and limit power.

 

Hmmmm...

 

How much timing is recommended for a 600 that spends most of its time beween 5,000 and 10,000 ft above sea level?
Also, I seem to be hearing that this will aid in dropping EGTs....gotta like that!

Mike

 

OK so I talked the guy into actually doing the timing adjustment. The thing is he is telling me there are two ways to do it. One on the pump and two on the gears under the timing cover. I dont know any better than to argue so can someone tell me if this is correct. Also, how many teeth on the gears do you have to adjust the timing. Are there any marks to see where your timing is set? From the factory it is set at 14 I believe my plate says, I want it at 16.5. Thanks in advance.

 

Tex, here is no two ways about it, to change the timing the gear under the front cover must be popped loose and repositioned. There is no adjustment on the pump proper unless you call the gear part of the pump. It's not a matter of teeth as the shaft is smooth.
I personally don't think your mechanic knows what he's talking about and would go elsewhere.
Best bet is for you to read the how to here
http://dodgeram.info/tsb/1994/18-10-94a.htm

There are a couple different methods, one involving a diesel timing light and the by rotating the dampener a certain amount of degrees, this method doesn't work unless you know exactly what the timing is set at before you start.

 

I still say

RUN !!

YOU NEED A NEW MECHANIC!!!!!

Yes you have to time it by moving the pump gear but NOT any gears or teeth under the cover.

: Eddie :

 

did the timing,did the valves,and what a great difference.more power.better mileage,starts and runs better. Done by a Cummins cert. mechanic. JUST DO IT!!!!