Re: Tom Johnson's Rebuild??

["Al Powell" <APOWELL@agcom.tamu.edu>]

Paul_G._Christie@intouch.mpx.com.au (Paul G. Christie) correctly said:

>> a-powell1@tamu.edu,Internet writes:
> >
>> HOWINHELL can it be an ignition problem??  Can't Happen!!!  The 
>> ignition has NOTHING to do with mechanical wear in the cylinder 
>> walls.  It has to do with igniting the fuel/air mixture at the 
>> right time.
> 
> I agree with the rest of your post but the ignition has a hell of a lot to do
> with mechanical wear. detonation (pre ignition) will play havoc with
> rings,cylinder walls and pistons to the point wear it can burn a hole in the
> top of a piston etc. Also a simple thing like retarded timing will cuase the
> motor to run exceccissvly hot and damage rings and bores etc.
> 
> I'm not saying that this was the fellows problem  just that things should be
> understood before advice is given so as not to confuse people. I notice this
> goes on a lot in this mailing list. 

WELL put!  But let me state a counter-argument and my reasons for it.

I considered ignition but still think that it is highly 
unlikely to affect the rings.  **As far as I am aware** (note 
qualifier, as I am not an expert in this area) detonation would first 
damage the piston tops and probably melt through them before 
affecting rings.  Ring problems, *in my interpretation* would be a 
much later effect of excessive detonation. 

You are 100% right about heating - but in my experience, an engine 
has to get REALLY, REALLY hot before getting hot enough to take the 
temper out of the oil rings, which can certainly cause excessive oil 
consumption.  I have seen this happen, but NEVER to an owner who was 
not aware that he/she had gotten the engine much hotter than was 
permissable.

I have never heard of an engine getting hot enough to lose the temper 
from the main rings.  Therefore, while I certainly agree that timing 
problems, epecifically excessive detonation or grossly innacurate 
timing, could cause damage to pistons, I think it highly unlikely 
tht damage would PREcede such severe damage to the pistons that the 
rings would be the most suspect item.  Nor do I think that he could 
get the engine hot enough to damage the rings without knowing full 
well that he had done so.

O'course, this is theorizing.  The proof will come when he pulls the 
head and sees the piston tops.

BTW: I have seen a Ford 302 V-8 get SO hot that the babbit material 
from the main bearings ran ito the pan and formed pellets - so hot 
that every major component was warped and not one major part was 
salvageable.  But it ran well - until they turned it off....then it 
was toast.  Had to sit for three hours before we could remove the 
radiator cap, and even then it shot a geyser!

I say the above not to pick a fight, but to explain the reasoning 
behind my comment.  YOU may have it exactly right! It will be 
interesting to hear the outcome.
Al Powell                           Voice:  409/845-2807
107 Reed McDonald Bldg.             Fax:    409/862-1202
College Station, TX 77843           Email:  a-powell1@tamu.edu 
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"Baseball is 90 percent mental.  The other half is physical"...
...Yogi Berra.