34 replies to this topic

[Ozymandias]

I've got a '95 SPi, Jap spec. I decided to adjust the tappets because they were a bit noisy and hadn't been done for ages - but having done so, using what I thought was the correct feeler gauge (.306mm) and "Rule of Nine", they're noisier and more clattery than ever!!

 

What have I done wrong...?

 

Thanks for any advice...

[dklawson]

Was the engine fully cold when you adjusted the valves?  What setting did you use (is there a possibility you confused millimeters and inches)?

[Cooperman]

When using 'rule of nine' make sure that the engine is fully cold and that the valve which should be fully open is, indeed, fully open.

[jaydee]

Sounds like worn rockers

[liirge]

I came here to say there are three or four things to check:

 

1. Correctly set, as above make sure that the valves are fully open.

2. There maybe excess wear on the tappets where they come into contact with the valve, this will mean that it will be almost impossible to set the correct clearance.

3. Have a careful listen, the cam followers may be the problem, when they are badly pitted and/or worn internally they make a very loud noise.

4. Rocker shaft and bushes, if either are worn the correct tappet clearance will be impossible to maintain.

 

Additionally,

If you have roller rockers installed, remember to check the clearances from the side, and not from the front.

Edited by liirge, 23 February 2015 - 01:52 PM.

[nicklouse]

 

 

Additionally,

If you have roller rockers installed, remember to check the clearances from the side, and not from the front.

interesting. first time i have heard of this.

 

can you explain?

[jaydee]

Roller needs to be adjusted with the feeling gauge moving side to side and not back and forth, thats due to the nature of the roller rockers..

[jaydee]

I came here to say there are three or four things to check:

 

1. Correctly set, as above make sure that the valves are fully open.

2. There maybe excess wear on the tappets where they come into contact with the valve, this will mean that it will be almost impossible to set the correct clearance.

3. Have a careful listen, the cam followers may be the problem, when they are badly pitted and/or worn internally they make a very loud noise.

4. Rocker shaft and bushes, if either are worn the correct tappet clearance will be impossible to maintain.

 

Additionally,

If you have roller rockers installed, remember to check the clearances from the side, and not from the front.

 

Welcome back liirge, been a long time!

[nicklouse]

Roller needs to be adjusted with the feeling gauge moving side to side and not back and forth, thats due to the nature of the roller rockers..

i still dont see the reason.

 

a flat top of a valve stem. a cylindrical roller and a flat gauge.

I can not see a reason and i am trying to.

[Ozymandias]

Was the engine fully cold when you adjusted the valves?  What setting did you use (is there a possibility you confused millimeters and inches)?

Yes, the engine was fully cold - I used a .306mm gauge (My Haynes Manual says .30mm is right). Could it be that the rocker faces have little "pockets" in them where the valve stem has been bashing them over the years, and this is why I'm not getting the right distance?

[liirge]

 

Roller needs to be adjusted with the feeling gauge moving side to side and not back and forth, thats due to the nature of the roller rockers..

i still dont see the reason.

 

a flat top of a valve stem. a cylindrical roller and a flat gauge.

I can not see a reason and i am trying to.

 

In short,

You don't want the roller to roll when measuring the tappet gap, by going in from the front that's what will happed.

[cal844]

Set them at 10 thousandth of an inch, or 0.25mm

[dklawson]

I believe 0.010 is a bit tight for standard arms but should not cause problems under normal conditions.

 

Oz, if the valve stems have damaged ends, the rocker tips have flat spots, or the tappets and/or cam lobes are damaged ( as Liirge said) then they will be nearly impossible to correctly adjust and they will be noisy.

 

Also, as Liirge said, roller rockers are supposed to be set by sliding the feeler gauges in from the side.  With roller tips thicker feeler gauges can be inserted into the gap as the roller turns.  It's as if the joint almost draws in a thicker feeler gauge than should fit.  The end result is that if you insert the feeler gauge from the front the gap can be set "too tight".  

 

Finally, valve noise is disturbing but the old saying is "It is better to hear a valve than burn a valve".

[cal844]

On my standard 998(1989) manifold it states 8-12 thou

[dklawson]

I don't dispute you may have seen those figures but they do not match what I have seen in Haynes.  I have a PDF Haynes at work that confirms what Steve says in the thread linked below.

All engine types except 12A  0.30 mm (.012")

12A engines  0.33 to 0.38 mm (.013-.015")

 

For reference see this old thread.  

http://www.theminifo...626-tappet-gap/