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jjrosty 
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Joined: 15 Sep 2009
Location: Broken Arrow OK
Points: 121
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 Topic: D12 rocker adjust studs too short
Posted: 17 hours 8 minutes ago at 10:41am |
I acquired a D12 last year as a pile of parts. The rocker arm adjusting screws did not have lock nuts & the adjustment screws are too short for locknuts, they are bottomed out in the rocker arm. The push rods are the correct length 9.25” The possible causes are endless. What would be the best way to resolve this situation. I think B push rods are 9.8” long could I replace them? Any useful opinion for a fix would greatly be appreciated .
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If you always do, what you always did,
You'll always get, what you always got
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DrAllis
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Joined: 12 Sep 2009
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Posted: 15 hours 21 minutes ago at 12:28pm |
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The adjustment screws should be long enough for a jam nut. So, get some that are long enough and the problem is solved.
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steve(ill)
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Joined: 11 Sep 2009
Location: illinois
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Posted: 15 hours 14 minutes ago at 12:35pm |
are you saying the adjusting screws MIGHT be the right length, but they are screwed in 1/2 inch too far ? If that is the case, there should be a LOT OF THE SCREW sticking out of the rocker arm ??.. If you adjust the screw out so it looks "like a good location".. can you get the nut on and the pushrods are just 1/4 - 1/2 inch too short ?? Do the valve springs look like the valves are long enough sticking out of the top of the head ? Valves not compressed too much ?
not an exact science, but the ROCKER should set about perpendicual to the valve stem and the pushrod... just a visual check for "normal" rocker position.
Edited by steve(ill) - 15 hours 3 minutes ago at 12:46pm
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Like them all, but love the "B"s.
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steve(ill)
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Posted: 14 hours 53 minutes ago at 12:56pm |
here is a drawing from the "B" service manual.. Shows the rocker arm setting about horizontal.... You should visually be able to tell of your rocker is too far toward the pushrod or too far toward the valve... That would tell you which side the problem is on... assuming your adjusting screws are proper length to have the ball sticking out on the bottom and the nut installed on the top...
Edited by steve(ill) - 14 hours 47 minutes ago at 1:02pm
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Like them all, but love the "B"s.
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jjrosty
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Location: Broken Arrow OK
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Posted: 11 hours 16 minutes ago at 4:33pm |
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I’ve thought of that. Where would someone source longer rocker arm screws?
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If you always do, what you always did,
You'll always get, what you always got
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jjrosty
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Location: Broken Arrow OK
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Posted: 10 hours 30 minutes ago at 5:19pm |
my understanding is that the head was “rebuilt”. I’ve looked for specs on valve spring height, rocker screw length, rocker tower height etc etc. but have found nothing. I’m not sure what was used for the “rebuild “
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If you always do, what you always did,
You'll always get, what you always got
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DrAllis
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Posted: 10 hours 22 minutes ago at 5:27pm |
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You must have jam nuts on your adjusting screws to keep the valve lash setting locked to where you set it at (.015" cold). You say the screws are too short. So, you must have the wrong (too short) screws and are missing the jam nuts. I'm fortunate to have salvage yards not far from where I live. I guess if it was my problem, I'd just buy a complete used rocker arm shaft assembly from a salvage yard. D-10-12-14-15 engine parts should be all the same I think in this area. Not so sure parts from a B-C-CA might work too.
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SteveM C/IL
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Posted: 9 hours 49 minutes ago at 6:00pm |
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Are the push rods in the lifters or setting beside them?
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steve(ill)
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Posted: 7 hours 54 minutes ago at 7:55pm |
look at the drawing above... is the HEIGHT of the PUSH ROD above the head ( valve cover face) about the same as the height of the valve SPRING above the head ???
SteveM has a good question ......... about seating the push rods correctly.
Edited by steve(ill) - 7 hours 52 minutes ago at 7:57pm
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Like them all, but love the "B"s.
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