Rockers (and Mods!!)

[Gareth]

Hello there!

Could one of you kind souls tell me how to adjust my rocker clearances - the "Idiot's Guide" please?

I know about the rule of nine, but the book on car maintenance I have (sad but true... ) gives conflicting info.

Firstly it says to use the RO9, which ensures that while one valve is fully open, another will be fully closed - then it's the closed one I must check (and adjust to 12 thou?).

Later on, it tells me that to fully close a valve, I need to make it fully open, and then turn the crankshaft one complete revolution (the starting handle will come in handy here, methinks!). Turning the shaft will puts the tappet on the heel of the cam... Both theories make sense, but which is better?

How do you guys (and gals) do it?

[Willie]

Lo, use the rule of nine and the job is made much easier
because you have a starting handle so do use it. You should
have a new cork rocker cover gasket standing by? do not
overtighten the two rocker cover bolts just enough to pinch
the cork is sufficient check for leaks after a few miles and
pinch up slightly if there is a leak.
YES IF ,SAY, VALVE NUMBER ONE IS FULLY DOWN i.e. OPEN
then under the rule of nine No.EIGHT is at maximum free
play and should be set to 12thou" etc etc
Willie

[Gareth]

So that's what it's all about!! When they're closed they're open, and when they're open they're closed...

It all fits into place now. I reckon I can cope with that!

Yes, I do have a new gasket hanging in the garage.
Thanks, Willie.

[les]

I believe some people adjust tappets with the engine running, although I have not gone that far, I have checked the clearance that way. It's suprising how you can still feel if the clearance is tight or loose.

[Willie]

Yes Les, I have tried it that way too and it certainly works,and
you are getting the clearance reading under actual working
conditions but,apart from the fact that oil is spitting all over
the place,you still have to stop the engine to adjust comfortably
so I wouldn't recommend it to Gareth.
Willie

[Gareth]

Thanks for all your help, Willie and Les.

The rockers are adjusted, the points and plugs set, and she's running very nicely indeed.

I really didn't fancy the idea of trying to get the feeler gauge in between the arms with the engine running! I had enough trouble sorting it out with them staying still!! Ah well.

Thanks once again - I know how to do it now!!

[tuning72]

Hi
Please don`t say "tappets" As I have pointed out previously, Tappets are really "Cam Followers" "Adjusting Tappets" comes from the Side Valve engines, when that is what was done to adjust valve clearances. A decent mechanic will always use the correct term. On OHV engines you adjust the Valve Clearances, via "Rockers".
I guess you know that TWO valves operate at the same time, so it is possible to adjust two at a time. Same principle--Adjust opposites.
If you do other engines,watch out for different firing order!
The only time I know of adjusting valve clearances when engine running was on "Perkins" Diesels. We had a roll of strip feeler guage and cut off a new peice for each valve. The rocker used to "Hammer" the guage and give a false reading if used twice. The idea was that all wear was allowed for. Similar reason that doing cam dwell when setting dist. contacts rather than manual gapping is always best.............Ivor.........

[les]

There you go again t72. The term 'adjusting tappets' is generally recognised as meaning to adjust the valve clearance by most people, rightly or wrongly. You expect too much of us mortals t72, and you are rather cheeky to say you have told us of our error before! Maybe at one of your lectures, but not here please.