Rule of 9 ?, 13 ? whatever

[WokingWedger]

Ok when checking/setting tappets on a 4 pot, I remember using the rule of 9, ie when no. 1 is on the rock, set no.8 , 3 and 6 etc.

Is there a way of know when a rocker is definately off cam, by seeing when others are on cam.

Rob was kind enought to tell me set no. 1 inlet when no. 6 was on the rock, but what about the rest.

I want to check them all

[spend]

It depends on the firing order...

1-8-4-3-6-5-7-2

1&6
8&5
4&7
3&2

When inlet on is open the paired inlet should be on base circle, same for exhausts. Basically that way you are setting when crown is opposite follower.

[WokingWedger]

Cheers Dave.

So let me check I have got this straight.

With no 1 inlet valve open - check pre-load on no 6 inlet
With no 8 inlet valve open - check pre-load on no 5 inlet
With no 4 inlet valve open - check pre-load on no 7 inlet
etc

and

With no 1 exhaust valve open - check pre-load on no 6 exhaust
With no 8 exhaust valve open - check pre-load on no 5 exhaust
etc

is that correct ?

[WokingWedger]

WokingWedger said:

Cheers Dave.

So let me check I have got this straight.

With no 1 inlet valve open - check pre-load on no 6 inlet
With no 8 inlet valve open - check pre-load on no 5 inlet
With no 4 inlet valve open - check pre-load on no 7 inlet
etc

and

With no 1 exhaust valve open - check pre-load on no 6 exhaust
With no 8 exhaust valve open - check pre-load on no 5 exhaust
etc

is that correct ?

[spend]

Yes, think about it some more, the sequences in the engine are quite logical & the more you ponder it the clearer it will become I'd say.

The only thing to worry about is how perfect the base circle on the cam is, running a DTI on a follower around the base circle may bounce more than tolerances you expect... but then again I'm not convinced that shims etal setting preloads is necessary, if out of tolerance it's probably worn/wrong followers/pushrods/rockers/shafts/valve stems/seats overcut... Try and make up your own picture on a piece of paper to visualize all these things moving about?