How many revs should my engine be doing?

[Lakesailor]

The hand crank is either on the cam shaft or on a geared shaft. The cam shaft will spin at half engine speed. ( http://pdf.directindustry.com/pdf/l...irect-injection-diesel-engine/5772-61328.html )

 

[lynall]

Why not just check the tester on your car if its got a rev counter, rough but will give you an idea?


Lynall

 

[Quidi Vidi]

Why not just check the tester on your car if its got a rev counter, rough but will give you an idea?


Lynall

You are a genius! I'll give that a go tomorrow.

Thanks for that Lakesailor, that makes the readings make more sense.

I've had a lot of problems with the engine and had to replace the head after the original corroded through the salt water it flooded the cylinder. I can't afford to re-engine and have not been able to sail for the past year while I have been rebuilding the engine. I'm not a mechanic so it's been a long process and steep learning curve, hence the need to check that the engine is running correctly, I need to be able to trust it before we go for a sail.

 

[VicS]

Originally Posted by lynall View Post
Why not just check the tester on your car if its got a rev counter, rough but will give you an idea?


Lynall


You are a genius! I'll give that a go tomorrow.

But check you car rpm at the crankshaft pulley ... that may be easier said than done if its a modern car with all the rotating parts guarded or well hidden from view.



Then check your boat engine rpm at the crankshaft pulley too.

 

[ffiill]

As per Lake Sailors reply-hand crank is on camshaft to give extra umph when trying to hand start-therefore double values and you have what is expected.
Its very easy when trying to sort out an engine to go completely off track and often assume the worst-if it will push the boat along in a flat calm no tide at 5/6 knots its probably perfectly alright.
Sometimes having all the gauges can get you quite obsessed-cars rarely used to have rev counters or oil pressure gauges or ammeters or voltmeters.

 

[Bosun Higgs]

Whilst trying to sort my engine out today (posted in another thread) I used a hand held laser rev counter to see how many revs we were doing as we don't have a rev counter fitted and I've always wondered about this. At idle we seemed to be doing just over 500 rpm, in neutral at full chat about 1600 rpm and in gear at full chat whilst still tied up just over 1200 rpm. My owners manual suggests max rpm should be 3600 rpm, am I missing something? My knowledge of these things is pretty basic to say the least!

Either your measurements are wrong or there is something wrong with the engine. I would lean towards the latter because if you were reading half engine speed and maxing out at 3200 no load your idel would be1000 rpm which is definitely too high and your max would still be short of what it should be. Nevertheless, get the readings right first.

 

[ianj99]

The Mini 6 is nothing like the old Lister engines. High speed engine (3600). Main market refrigeration units on trucks, portable gen sets etc where light weight and simplicity were important. Lots of aluminium bits and only partly successful when water cooled in marine applications.

Fair enough, and I did notice how small it was on a youtube video compared to the old man's 8hp Lister.

However surely the OP is able to tell whether it is idling at about 500 or 1000 without a tacho? Ditto whether its maxing out at 1600 or 3200rpm, especially with it being a single.