Checking xflow valve clearances

[ashaughnessy]

I know how to check valve clearances using the rule of 9 - get valve number "n" so it is fully open and valve number "9 minus n" will be fully closed and can be checked.

However I'm sure I was once taught an alternative method, one that wasn't so dependent on guessing whether the valve was in the fully open position. Can anyone tell me what this might have been?

Anthony

[DohNut]

 

But as the valve is closed for a lot longer than it is open you dont have to be at the exact peak of lift for the 9-n valve to be closed.

If in doubt advance and retard the engine a bit and recheck if it is unchanged then You had it right

 

nick

[Graham Sewell]

on the rock - so if the exhaust on a cylinder has just shut on cylinder 1 and the inlet is just starting to open, then you can assume that both valves are fully shut on cyliner 4 - based on a rule of 5 (if you see what I mean)

 

with less agressive cams, there is a small gap in time when both valves would be closed and you can just rock the rockers on cylinder 1 in the above example.

 

It still takes 2 full turns of the engine and on my car the results are close enough to be identical (no more than 1thou difference - normally just a feeling of slight sloppiness or tightness on the feeler gauges).

 

Cheers,

 

Graham

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Low tech luddite - xflow and proud!

[ashaughnessy]

Graham - "on the rock" - that's what I remember! Thanks.

 

Advance and retard - I've always been worried about turning the engine backwards - is it OK to turn it the wrong way?

 

Anthony

[Graham Perry]

Don't get too hung up on absolute accurancy of crossflow valve clearances. There is an explanation from Roger King here. I have seen it written elsewhere by other tuners that the crossflow is not too sensitive to the clearances

 

Edited by - Graham Perry on 4 May 2006 18:29:26

[ashaughnessy]

Thanks for the info.

 

As an aside, I have a low poundage torque wrench that I rarely get to use - does anyone know the correct torque setting for the rocker cover bolts? Usually I just nip them up, but as I have the torque wrench I might as well use it.

 

Anthony

[Nigel Riches]

Anthony, I think the rocker cover screws are torqued to 6 lb/ft, same as the sump bolts. Nigel.

 

1982. 5 speed, clamshells. B.R.G / Ali. The True Colours.

[susser]

I use the "on the rock" method;

It's easy with most 1342 firing motors 'cos when No1 is at TDC firing, the other piston at TDC will be 4 which will be at valve overlap.

Therefore No1 will be bothvalves closed, and vice versa.

Same applies to the other pair, 2 and 3.