How do you turn up a 3116 cat

It is rather simple. Remove the valve cover, at #1 rocker stand one of the bolts will hold down a smal metal cover. Remove the bolt and cover. In between #1 & #2 rocker stand will be a small jam nut and screw on the rack bar. To increase rack travel on the injectors turn the screw counter-clockwise. Retorque bolt back to 22 ft. lbs

To advance inj. timing slightly break loose inj. lock nut on center rocker. Turn in the adj. screw roughly 3/4 of a turn. This should put you at advanced side of the spec for the engine/inj. combination.

The 3100 family is more or less a throw away engine, but can be a rather good unit. One of the biggest complaint I have seen with higher milage units is a customer that brings one in and wants inj. replaced. Reman inj. runs alittle over $100 a piece. If the inj. sleeves needs replaced along with parts and labor the bill can go up to around $2000. After good hitting inj. are put in and timing set to where it needs the engine has alot of blow-by.
One easy check for inj/cylinder condition you can do on your on is to remove the valve cover and get engine up to operating temp. With a screw driver go in from the exhaust manifold side and at the base of the inj. is a small link rod that turns the barrel in the inj. You can manually push the small rod back towards the drivers side and place each cylinder at full fuel on at a time to detect how well each cylinder is doing. Also you can watch the blow-by tube for signs of something not up to par for that cylinder as well.
You might want to check the diaphram in the air/fuel ratio in the govenor also. Remove small meal tube that runs from intake passage to govenor. The fitting on the govenor will be on the side. Apply 10-12 psi of air pressure to the fitting in the governor. Snap the throttle back and forth and watch the exhaust. With air applied you should get a big bloom of black smoke and without air applied not much smoke.

Also check the muffler. Unless the muffler has been changed it will contain a cat. converter. You could also be getting back pressure build up in it also.




The engines do have some other small quirks about them. The inj. syncheration and timing has to be done with dial indicators. The bottom sealing area on the injector also needs to be sealed special seating tool to crush the injector into the sleeve.

If the top end adjustment has not been done on the engine in long time it may need a trip to the dealer.
If the engine runs rough in the morning with lots of white smoke it could indicate that compression is getting into the fuel rails from around the lower seal area. If the engine does not show this signs you could get by with only turning the fuel up and advancing fuel timing.


If you have any more questions feel free to ask.

Ken