[Mgs] tappet question

Clayton Kirkwood crk at godblessthe.us
Mon May 18 11:03:45 MDT 2015

Regarding Rule of Nine, I understand having 8 all the way up to set 1. But
there is a significant rotation between "real close to the top" in front of,
and after TDC. This can be seen with rotation the engine and seeing very
little to no movement. Also, if I am not mistaken 8 TDC is not perfectly in
line with BDC of 1; there is a bias. This means that when 8 is TDC, 1 is not
absolutely BDC ready for measurement. So the question is, how do you ensure,
with all of that slop, that you truly have BDC?






From: PaulHunt73 [mailto:paulhunt73 at virginmedia.com] 
Sent: Monday, May 18, 2015 12:25 AM
To: crk at godblessthe.us; mgacars at yahoogroups.com; mgs at autox.team.net
Subject: Re: [Mgs] tappet question


Depends on the figure you used.  Workshop Manual quotes 15 thou, cold.  I
don't like hot as the engine is continually cooling while I'm doing it.  I
use 14 thou which is loose and 16 thou which is lightly pinched so I can get
a better feel for it as I only check them very rarely.  As far as I know it
really only makes a difference if the engine gets so hot that the gaps close
up and you get combustion seepage past not quite closed valves, which burns
them.  Any loss of performance is only secondary.


In the early years not only did I find I was adjusting them every year,
sometimes opening them and sometimes closing them, but also getting
repeatable gaps from one turn of the engine to the next was a problem.  Then
I discovered that at the strict rule of nine (RON) points, several of the
valves were still changing gap.  Some of them had the biggest gap before RON
and some after.  Since discovering that perhaps 15 years or go or more I've
never had to alter them until I changed the head gasket last year, so hadn't
been checking tem every year anyway.



----- Original Message ----- 


When I went to reset the tappet clearance, I found the old settings rather
sloppy. I reset them so that the gauge was snug - it slid in but it
definitely tight. Which is correct? I know that it makes a difference on
performance and full combustion. Yes, I did the checking while hot.

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