34 replies to this topic

[liirge]

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/

Can confirm, I am looking at a manual right now. 

[Mini Manannán]

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/

 

Interesting, my engine didn't have a number at all, only the six(?) digit number in the log book.  So I have no idea if it's a 12A or a 12X.  What is the difference between the two designations?

[nicklouse]

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".

I read what you say but why would you be feeding a thicker gauge in than you want?

I suppose I am more a clearance setter rather than checker.

[Cooperman]

A tip here if I may.

If you have one or two noisy rockers run the engine from cold at low tickover with the rocker cover removed. Use a 'spare' feeler of about 0.006" and feed it under each rocker in turn. That will establish which rocker(s) is(are) noisy. The feeler gauge will probably be scrap afterwards, but where else do you use a 0.006" feeler?

Switch off, re-set the 'dodgy' ones, wipe away any slight oil from around the edge ad re-fit the cover.

[Spider]

Sounds like worn rockers

 

Yeap, I was about to say the same. Check the shaft too.

[dklawson]

I read what you say but why would you be feeding a thicker gauge in than you want?

 

 

I guess you and I are thinking about this differently.  Once I have set rocker clearance I try to pull the "correct" feeler gauge out of the gap feeling for how much drag is on the blade.  If you go back and check with the next thicker and thinner feeler (as a go/no-go check), it's easier to fool yourself as the thicker gauge will slide into the roller gap if inserted straight-on.  If you slide the feeler  "sideways" into the gap, the roller doesn't "draw" the thicker gauge in and give you a false reading.  Also if you are used to feeling for drag with the "correct" feeler gauge, you will find less drag with the correct blade and find yourself using thicker blades to get the right feel.

[nicklouse]

I read what you say but why would you be feeding a thicker gauge in than you want?

 
 
I guess you and I are thinking about this differently.  Once I have set rocker clearance I try to pull the "correct" feeler gauge out of the gap feeling for how much drag is on the blade.  If you go back and check with the next thicker and thinner feeler (as a go/no-go check), it's easier to fool yourself as the thicker gauge will slide into the roller gap if inserted straight-on.  If you slide the feeler  "sideways" into the gap, the roller doesn't "draw" the thicker gauge in and give you a false reading.  Also if you are used to feeling for drag with the "correct" feeler gauge, you will find less drag with the correct blade and find yourself using thicker blades to get the right feel.

Yep get what you are saying. Must fess up to not having done any non roller tipped or full roller rockets for a very very long time. But saying that I have a Midas to to set up at the weekend with standard rockers.

[cal844]

Personally id try closing the gap ( lets say to 10 thou) on each in turn, if it doesnt quieten, revert to previous measurement(12 thou)

[Earwax]

are you sure your clattery noise is rockers,? are they now hitting the rocker cover?  how is your timing chain? 

[Ozymandias]

Thanks for the feedback, everyone!

 

I don't think the rockers are hitting the cover as it's just as clattery with the rocker cover off.

 

Having felt the underside of a couple of the rockers, I think the faces may have pockets worn in them, so I'm tempted to replace the rockers (and the rocker arm, just to be sure!)

 

Is this a fairly straightforward job - whip off rocker bar, replace rockers, springs etc, re-adjust, sorted...? Or is it more complicated than that?!

[nicklouse]

if there is pockets that that is the issue.

 

I would replace the whole lot. Ok the posts will not have worn (they dont move) but it is easy to build up a new set and fit them complete.

 

if building them up from parts be aware of the oil feed if the posts dont all have oil ways in them.

[Ozymandias]

I think I may have discovered why the rockers were noisy - see attached pic...!

 

They weren't all as bad as this, but they were pretty bad. In the end I had to take the whole rocker assembly off - my "just slide out the shaft" plan didn't work.

 

I'm hopeful that I haven't disturbed the head gasket in the process - she ran very well on my 15 mile journey to work, no overheating issues - I'll be keeping an eye on the quality of the oil, though.

 

 

Attached Files

•  IMG_3598.JPG   58.19K   36 downloads

[liirge]

Wow that is really worn. Worryingly so.

[Spider]

Thanks for up-dating us.

 

Looking at that rocker, I'd be a bit sus that the valve guides may also be rather worn too.

[liirge]

I'd also wonder how that cam follower is.