[T3] AFR readings

[mark witwicki]

>
> When romping the throttle, fuel mixture goes from 13.8 to as high as  
> 14.5.  Do not know how accurate the latter figure is, but figure the  
> fuel mixture should get richer right?
>
> I did find out from a posting of Keith's that the ratio should be  
> somewhat linear and cruise should be no higher than 14.1.  But  
> nothing on W.O.T. acceleration.
>
>
> 10.5 - 11.5 WOT, but it depends on where the sensor is mounted etc.   
> what
> matters is smooth acceleration.
>
> Keith
>
>
>
> I am using a borrowed exhaust gas analyzer so it is from the  
> tailpipe.?
> So I am right in my thinking that the mixture should become more  
> rich.? As
> per what you stated on theSamba the inner stop needs to be turned  
> in.? Have
> you since figured out how much of a turn affects the mixture?? What  
> if I
> mess up the adjustment?
>
> So long as the acceleration is smooth it can run lean?? I was told  
> it would
> not allow good acceleration, so thus my questioning.? Also do not  
> want to
> ruin an just rebuilt engine, especially my first. ;)? Working on a  
> second,
> but just a tear down and replace rings and anything else out of
> specification/worn/damaged.
>
>
> Thank you,
> Adriel
> 		 	   		   Short article on enrichment and running temps

I recently read a post where someone was stating they were afraid to  
lean their engine out because they were afraid of losing a valve seat  
or making the engine run hot. They were complaining about the engine  
being a "Gas Hog". I'd like to explain something about this:

This makes zero sense to me. An engine that is out of tune will RUN  
HOTTER even if it is pig rich!! Fuel may be a bit of a cooling agent,  
but too much creates inefficiency which breeds heat! I have had  
engines run hotter when they were over enriched and they got shitty  
mileage and they had no power.

How about this:

Install GAUGES to MONITOR the head and oil temps so you know if the  
engine is hot or not. WOW that makes sense! Don't cheap out and build  
an engine that you can't afford to monitor.

What this person doesn't realize is that he is HARMING the engine by  
running this much enrichment, here is how:

1- Running this rich washes all the oil from cylinder walls. This puts  
a hefty glaze on cylinders FAST and rings as well, these then refuse  
to properly seal which leads to combustion byproducts contaminating  
the oil past the rings.
2-The heavy fuel content and combustion byproducts will KILL the oil  
in no time, it effects the viscosity of the oil greatly and can make  
the oil virtually worthless.
3- The engine can suffer irreversible damage from this sort of  
application because the cylinders and rings can become so glazed that  
they will not seal and a result is a loss of dynamic compression,  
increased crankcase pressure and virtually an engine that acts like it  
is worn out.

The moral of this story is simple: Enrich the engine 12.5-13.2:1 under  
WOT up hill. A cruise AFR of 13.5-14:1 is fine with light load.

Running rich on purpose is going to do nothing except waste gas, waste  
parts and ruin your day.
Think about it.
__________________
Jake Raby



Adriel , your car will show a leaner reading at anything but WOT  
because of the air that mixes with the exhaust.
Mark Harney runs his bay window bus in the 16's at cruise with good  
mileage and no detonation problems.

Find a hill so you can load the engine while testing, put it in 3rd  
gear at around 1500rpm and floor it through the rpm range. That will  
tell you what your engine is doing under WOT.
You should really look at the graph to see what the motor is doing if  
you have access to recording the output.
My LM2 has the ability to play back recordings on the screen or see  
them on the computer after.
like this http://s165.photobucket.com/albums/u45/CDNBullyboy/LM2%20logs/?action=view&current=mark62idle-162main-180air.jpg
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