Overhead

[Rawze]

(09-11-2016 )dbl overdrive Wrote:  No or less than.20 after proper adjustment.
When I checked it with a dial indicator, pushing down there is 0 on 2 of the jakes.
I'll post a pic in a bit.

and...

(09-11-2016 )Signature620 Wrote:  Do they have a lot of travel between detent position and the cam lobe? Sounds like you need to loosen the rocker shafts and rotate them to bring the jake running clearance back into the correct range. I can post the procedure if you don't have access to Quickserve.

You cannot do this on an ISX 871! -- The valve rocker shafts have flats in them to prevent this kind of adjustment. I would not recommend this, as you would have to leave the bolt loose/under-torqued where the flat is, creating an oil leak at the joint and reducing oil pressure into the rockers.

However .... It is NOT a bad idea to ensure the rocker shafts are in fact seated properly, and aligned with the flats correctly. THIS, you can certainly check/re-set correctly, but NOT purposefully twist it out of alignment with the flats!.

Cummins is FULL OF shi#t ON THAT PROCEDURE!!! -- It only serves to mask other problems like the pistons protruding too far downward from the rocker assembly, broken set screws, flattened bearings, etc. and/or a very worn out head!.

If you are doing everything right, Correct crank position, correct clearance, adjustment, etc... and the engine brake piston (inside the rocker itself) is NOT extended down or damaged,... and you have less than about 0.028" movement in the engine brake rocker after it is set properly between the detent position and the point of contact to the valve,... then your head is done! -- TOAST!. The exhaust valves are riding too high in their seats. -- It is time to replace the head before a valve snaps off and takes the rest of the engine with it. -- Adjusting the rocker shafts back is NOT a good solution at all, and masks the real problem no matter how you look at it!

To me,.. IT STILL SOUNDS LIKE you are doing something wrong, or something is assembled wrong,.. or you are having problems with the engine brake rockers themselves (pistons down, or broken/stretched set screws). It will NOT be that bad to have zero clearance (or even 0.020 for that matter) unless it is a VERY POORLY DONE RE-MAN HEAD, or there is a serious problem with the exhaust valve height!>

Trying to cover it up by rotating the shaft will only compound your problems, and/or destroy something.