3406 b performance

Hey guys I have a 4mg that I would like to get a little more bottom end performance out of. Seems laggy and turbo spool (or6957)doesn't start coming on till probably 1400 rpm. Not sure what has been done to the engine but it will pull 28 lb boost at close to 1000 degrees post turbo, has a 13sp and 3.55 rears in a 89 4964F WESTERN STAR.
Had the AFC rebuilt, New fuel lines, filter and supply pump.
What do you think hp is and will a different turbo get it going a little sooner?

 

Check boost corrector line from manifold to injection pump. It it is bad engine runs like with no turbo.

Boost corrector is a small diafragm inside injection pump to limit rack movement if no enought boost pressure (to avoid too reach mixture and black smoke).

 

Is this the same as the afc?

 

Yes it is the fuel ratio valve it runs from intake to top back of pump. Before you throw money at it have a tune up done on it by a sure nuff real cat man. There are so many little things that could cause this it ain't funny. I can tell you 1000 post turbo is a lot higher than I like to see one for sure. Mine is the opposite of stock but 750 post turbo is bout where she stays. If the guy is worth his sand on a Cat he will find the problem with a tune up. It could be anything from timing off which is my first thought to governor weight trouble. Be sure to do a bridge adjustment too

 

I'm guessing timing is off. The engine would not make 28psi if the diaphragm was leaking. For turbo I would switch to a modern BW replacement, a 177148 will work extremely well.

 

Ok will see if I can get someone to check timing...any ideas what timing is best on these trucks?
I had a new diafragm put in the afc and it is good. Thanks guys!
Anyone know of a good cat mech around kc or south that has timing tools needed?

 

The timing spec is scribed on the end of the pump cam.

 

No advance needed?

 

Definitely look at the advance, first . The 4mg advances that weren't completely updated, would disassemble themselves, and flyweight dowel pins going through your front gear train, ain't pretty.

 

Ok, I know my way around a b model Cummins but this cat is very new to me...I usually turn my own wrenches but need some direction. After start up the idle bumps up for a split second, which I thought I was told should be the advance working internally? If I need to check this any advice or steps?
The advance I was referring to was static pump advance...