Author Topic: Use of COV?  (Read 3651 times)

Eadie McCreadie

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Use of COV?
« on: October 10, 2007, 08:46:41 AM »
Hi

When starting up, the COV is screwed in.  But do you unscrew it the moment the engine fires, or do you wait a few minutes to undo it?

Or maybe you leave it screwed in all the time?

EM
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emerald

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Re: Use of COV?
« Reply #1 on: October 10, 2007, 10:30:39 AM »
Unscrew if running the engine with more than 30% load.


Stan

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Re: Use of COV?
« Reply #2 on: October 12, 2007, 01:23:30 AM »
According to the Lister manual, if you run a heavily loaded engine under high compression, the stresses on the moving parts are much greater.
Stan

cujet

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Re: Use of COV?
« Reply #3 on: October 12, 2007, 03:00:30 AM »
Get rid of it! The COV will cause nothing but trouble.

I eliminated my COV and could not be happier.

Chris
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Shadow

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Re: Use of COV?
« Reply #4 on: October 12, 2007, 05:03:25 AM »
What kind of trouble does it cause?
        I use mine for starting, after engine gets up to speed and levels out I unscrew it. I find it starts way easier, even starts on waste veg. oil if I forget to switch back to diesel before shutting down.

cujet

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Re: Use of COV?
« Reply #5 on: October 13, 2007, 05:18:04 PM »
While not all listeroids are the same, the comet combustion chamber volume for them is about 72cc. At least the ones that I have seen. Some as high as 74 to 76cc.

In any case, with the COV the compression ratio of a standard 6-1 with proper bump clearance of 0.045 inches will be about 17 to 1 with the COV in and 14.5 to 1 with the COV out. I am sorry that in the prev post I did not clearly state why. I was low on time.

In any case, with the COV out, and the above volumes, the Listeroid will not be as efficient or clean running as it should be. There is no reason I can think of to run a diesel engine at a 14.5 to 1 compression ratio. Sure it will run, but 17 to 1 will run much better, with less smoke, more complete combustion, less combustion chamber deposits and the like. In fact, it should be about 15% more efficient too.

The way the Indian machinists cut the comet combustion chamber is with some form of ball cutter. The result is excess volume.

Plus the COV can come loose while running, resulting in lots O noise and annoyance, maybe worse.

The Indian Listeroids function quite well with a plug installed, constantly running at the higher compression ratio. In fact, this is how they use them. In other words, your ease of starting would remain the same. Plus you would have the additional efficiency.

Chris
« Last Edit: October 14, 2007, 12:19:56 PM by cujet »
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