|12-10-2009 11:59 AM|
Occasionally, if not on TDC, the engine will rotate from the compressor's pressure. Keep hands and tools out of the way of the belts and fan, and for heaven's sake- turn the key to off (better yet, remove it and put the key in your pocket so a 'helper' listening to the radio or something doesn't turn the key to RUN. You wouldn't want to start the thing up by the compressor turning the engine over).
Instead of bumping the engine over w/the key (the easiest way to have the key left ON, BTW), use a breaker bar and socket/extension on the crank bolt to move from cylinder to cylinder.
|12-10-2009 11:46 AM|
Did you remove the rockers before you tried turning it over?
|12-10-2009 11:41 AM|
i believe the reason it ( the rope trick) didnt work for me is because of the heads im running. the chambers arent open to the whole cylinder and when i tried to bring the piston up, the rope would get pushed up to the head before it could make contact with the valves.
|12-10-2009 10:43 AM|
the ol' rope a dope trick. much more reliable, and not that difficult.
|12-10-2009 10:22 AM|
|poncho62||Just a note for people without compressors, or don't trust them......Take some nylon rope and shove it in the spark plug hole (leave a bit out)....turn so piston pushes it up.......change your seals.....lower piston, pull rope out.|
|12-10-2009 10:16 AM|
|engineczar||I always rotate the motor to TDC on the cylinder I'm working on. I wouldn't run any more than about 10-20psi or just enough to hold the valve up. This way if something happens like a sudden loss of pressure you won't drop the valve out of the guide. Running full line pressure can be enough to rotate the engine but isn't enough to allow you to break loose the locks from the retainers if they've been together awhile.|
|12-10-2009 10:13 AM|
|Sinister||Hmmm, something to think about.|
|12-10-2009 10:09 AM|
|ap72||I've seen plenty of cases of worn guides with steady vaccuum. I've also seen plenty of cases of shaky vacuum with excellent guides.|
|12-10-2009 10:04 AM|
|Sinister||Yes, vacuum is steady. Excessive vibration that steadies as RPM increases would indicate worn guides.|
|12-10-2009 10:00 AM|
|ap72||vacuum indicates your guides are good?|
|12-10-2009 09:54 AM|
|Sinister||Sometimes I get a little blue smoke at startup. Vacuum indicates that my valve guides are good. Motor is of unknown mileage, but good compression and oil pressure.|
|12-10-2009 09:43 AM|
|ap72||why do you need to change your seals? and just run it at full pressure. probably around 100-120 psi.|
|12-10-2009 09:17 AM|
Changing Valve Stem Seals SBC
I need to change out my valve stem seals on a 350 at some point. I have the spark plug adapter to hook up to my air compressor. What PSI should I use to hold the valves up with out turning the motor?