I have a 1982 m813 nhc250 it has the top stop injectors I want to do the overhead on it tomorrow. I have been doing research on here I just need clarification on a couple things. I barred my engine over and appears I have the markings i6vs , I did see another marking near it but not a continual additional set of markings . On Will Wagners post it said I should have a different marking like tbdc I might have that on there but I don't think I have a set of the those markings . Would I use the 16vs that should be outter base I need inner base . Other question is when I adjust the rocker down on to the injector push rod until it contacts the push rod then tighten 6 inch lbs . So when he rocker has full contact with the pushrod inside that's when I tighten 6 inch lbs just want to make sure that's correct . Thanks for any information .
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M813 top stop overhead questions
- Thread starter comike27
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You can adjust either way, IBC or OBC, If you choose OBC, at the 1-6VS mark look at the #1 and 6 cylinders. Which ever injector lever is pushed down...into the injector... and has loose valves, that is the one to start at. Torque the injector to 68-72 INCH lbs, valves at .014 and .027. If you choose IBC, mark at 1-6VS, valves loose on #1 cyl, you start at injector 3 and valve 5, injector is set at 6 IN LB and valves at .011 and .023. Continue in firing order for BOTH sets of rockers. 1-5-3-6-2-4. you did 3 inj, and 5 valve, move along to 6 inj and 3 valve. Get it? OBC will be less confusing.
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Careful, if you do it wrong, you can cause damage to parts.
You should make sure the accessory drive timing is correct before you get too far into things. If you set OBC, after you set your first set of rockers, let's assume cyl 1, put a socket with a 6 or 10 inch extension on the #3 injector jamb nut, if you started at 6, put it on 4 inj. Bar the engine toward the next set mark while watching the top of the extension. Just as the tool starts moving toward the exhaust, stop and look where the VS mark is. It will be within an inch of the pointer, that is OK, if it isn't, the timing is off. If that's the case, come back and say so and we can go from there.
You should make sure the accessory drive timing is correct before you get too far into things. If you set OBC, after you set your first set of rockers, let's assume cyl 1, put a socket with a 6 or 10 inch extension on the #3 injector jamb nut, if you started at 6, put it on 4 inj. Bar the engine toward the next set mark while watching the top of the extension. Just as the tool starts moving toward the exhaust, stop and look where the VS mark is. It will be within an inch of the pointer, that is OK, if it isn't, the timing is off. If that's the case, come back and say so and we can go from there.
I am planning on doing ibc because my engine plate says .011 and .023 for valve adjustment . Figured I would stick with that . What would be best way to check the accuracy of my accessory drive timing for ibc . I'm planning on starting on injector 3 valve 5 so once that adjustment is done , put a extension on the injector jamb of the next injector to be adjusted and bar the engine over when it rises the drive should b near the next mark on the accessory drive .
sandcobra164
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OBC made the most sense for me since I have non top stops. If the injector is down and the rockers are loose, adjust those valves. Go to the "companion cylinder" and adjust the injector. On inline 6 diesels the companion cylinder always equals 7. 1-6, 2-5, 3-4. I was confused early on because I think of injection as a positive rise of the camshaft pushing the injector. What happens in the NHC 250 is the injector plunger stays closed until the camshaft lobe drops, injector receives fuel, camshaft lobe raises, fuel is injected and stays closed until the next event.
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No, put the extension on 3 if you start at VS1-6 or A and do i3, v5. You will be setting the inj at the "top stop, zero lash" method, if the tag says .011 and .023, it should sat for inj setting TS zero lash. Bar the engine and watch, when the lever breaks, the mark will be around an inch or so from the pointer.
OBC, valves and injector on the same cylinder in firing order starting at 1 or 6 , IBC companion cylinder starting mid firing order, but in order, injector on one, then valves on the other.
OBC, valves and injector on the same cylinder in firing order starting at 1 or 6 , IBC companion cylinder starting mid firing order, but in order, injector on one, then valves on the other.
I did the overhead today used the ibc method it worked great the valves were close the injectors were way off . Cleared up the excessive smoke I was getting and I did check the accessory drive for accuracy it was correct . Thank you for the information it definitely helped clear up the process for me.