| Author |
Message |
JRV (Jrvall)
Intermediate Member
Username: Jrvall
Post Number: 2393
Registered: 11-2002
| | Posted on Sunday, September 07, 2003 - 4:56 am: | |
Intrepid here in the states sells the roller screws Phil mentions. However it's not reccomended to change over if the valve stem tips have become dished and pitted, until that situation has been remedied.. |
Phil Hughes (Ferrarifixer)
Junior Member
Username: Ferrarifixer
Post Number: 151
Registered: 7-2003
| | Posted on Saturday, September 06, 2003 - 11:38 pm: | |
DK engineering in the UK sell ball bearing tipped adjuster screws. Much better than the standard ones....in fact, a DK or GTO (both UK) engine rebuild is second to none. "Symbolic" use them for many jobs. |
JRV (Jrvall)
Intermediate Member
Username: Jrvall
Post Number: 2391
Registered: 11-2002
| | Posted on Saturday, September 06, 2003 - 8:49 pm: | |
250 Top ends 'can' have several different problems. the most common are, bad adjusting screw tips (pitted & worn), worn roller "bushings & shafts", worn valve stem ends. Any one of or a combination of the above will cause the effects you describe. Unless your top end is new, I would suspect all 3 are likely.
HTH's |
Phil Hughes (Ferrarifixer)
Junior Member
Username: Ferrarifixer
Post Number: 150
Registered: 7-2003
| | Posted on Saturday, September 06, 2003 - 6:44 pm: | |
Make sure your rollers (on the cam lobe end of the rocker) are perfectly round. As the cam turns, the rollers turn too...if they are worn out of round the gap will constantly vary and be impossible to set. |
Bill Steele (Glassman)
Member
Username: Glassman
Post Number: 371
Registered: 4-2002
| | Posted on Saturday, September 06, 2003 - 3:17 pm: | |
On a 128D engine:
I am finding that after adjusting the valves and turning the engine two complete revolutions, some of the valves have changed the gap. What is causing this? Sometimes they appear too tight, and on the next revolution a little loose.
Is this typical or am I expecting too much consistancy in all twelve. |