Cause for a broken rocker arm nut ?

[junkyardjeff]

I bought a 16,000 mile 302 for my 65 custom 500 and ever since I got the exhaust on it has one lifter ticking,since the motor sat for about 30 years so I thought one lifter that held a valve open was not pumping up so I took it apart for lifters and a change to a 4 bbl.  When I was putting it togather I noticed one rocker arm nut was cracked so I replaced it with a regular nut and lock washer untill I can get a correct nut,well I got it back togather and the tick is still there so could it have a broken valve spring and now it has a dead miss on the same side.  It always seemed to have a very slight miss at idle but now that I disturbed it who knows,I looked at all the pushrods and looked at all the valve springs but saw nothing abmormal.  Could a valve stuck and made the rocker arm nut crack and possibly break a valve spring.  Jeff

[enjenjo]

If it sat for 30 years, there is a very good chance one of the valve springs is weak from being compressed for that long. I would advise a compression check to pin things down.

[junkyardjeff]

I have the dead miss problem solved,I took off the cracked nut and replaced it with a regular nut and lock washer and that kept the valve open some.  I can move the valve spring around some on the valve that had the cracked nut so its looking like it a valve spring or possibly a guide problem.  Jeff

[Arnold]

Ford had "select fit"(length) pushrods .."non-adjustable" rockers in their 302's around the mid or a bit earlier 1970's. The lash adjusting nut was screwed all the way down(on the pedestal) and torqued. To "adjust lifters" to keep the lifter plunger in it's mid..optimal position..you were SUPPOSED to..lol..substitute a different..the correct length  pushrod. One of you guys help me out here. Weren't they color coded with a band on them?? I think so. At least I think the "service replacements" were. In the real world..you adjusted these just like any NORMAL lol..sbc..haha. When they were adjusted correctly if you could screw the adjusting nut down onto the pedestal and torque it without the engine  missing..that one was done. If it missed..you backed it off again and put a locking nut on top of it. Those nuts fractured because of shock loading.. because they were torqued solidly to the pedestal.This  usually happened before the pushrods bent or the rocker got a hole punched in it. This was usually caused by worn guides/carbon..and binding between the guide/valve stem.

  Me personally..my .02..if this engine was a keeper..I would back off all the rockers until they just barely ticked. Then I would put lock nuts on all of them. I would put some lifter stuff in the oil..drive it..flush it. This will give the lifters a chance for the internal parts to sort of "stretch" a bit..loosen up..past any gunk in there. Then re-adjust them all to the centre of their travel.