Author Topic: Hit and miss engine  (Read 552 times)

Offline ducati2242

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Hit and miss engine
« on: March 27, 2021, 01:45:31 PM »
This is my first build it has taken me about 6 weeks on and off to get it to here . I don't seem to be able to get it to run any faster than this and I haven't fixed the hit and miss yet . Do you think it is running fast enough or do you think I need to work on the carburettor to get it running faster . Thanks Guy

Offline michaelr

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Re: Hit and miss engine
« Reply #1 on: March 27, 2021, 03:09:51 PM »
If that was my engine I would be very happy with the way it is running, once the governor is adjusted for Hit and Miss running it will be even better, it's not a racing engine I think it's running at a reasonable speed.
Mike.
« Last Edit: March 27, 2021, 03:13:12 PM by michaelr »

Offline Dave Otto

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Re: Hit and miss engine
« Reply #2 on: March 27, 2021, 05:34:08 PM »
That is running pretty well, I sure don't see any need for it to go faster.
But I do prefer slow running engines.

Dave

Offline Brian Rupnow

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Re: Hit and miss engine
« Reply #3 on: March 27, 2021, 09:33:13 PM »
That is an excellent speed for an open crank hit and miss engine. They were never intended to run fast.

Offline ducati2242

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Re: Hit and miss engine
« Reply #4 on: March 27, 2021, 11:21:30 PM »
Thanks for the replies . I will start to dial in the hit and miss next .

Offline collbee

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Re: Hit and miss engine
« Reply #5 on: March 28, 2021, 04:03:10 AM »
I am very much impressed with your engine and wish I could build to the same quality.  :praise2:

Maybe further to brian's post .... most of the smaller hit and miss engines I have dealt with (typically 2 HP) usually run at a max of 500rpm. I have a 1908 2 HP Crossley with a 48 inch flywheel that has  a maximum of 500 rpm. I also have small 'open crank' 2hp engines out of the 1930 - 1950s with approx 40cm flywheels still running at 500 rpm. They all usually fire on every few strokes and only draw fuel (closed exhaust) when needed.

Typically they sound like this lol  BANG (exhaust remains open) ..  suck, suck, suck, suck, .. (exhaust closes) BANG ..

I have also found, on occasion, that the inlet valve spring and/or the governor spring can be 'softened' in many cases ~ allowing the engine to run as a true hit and miss at lower speeds.

I sometimes wonder if heavier flywheels on model 'hit and miss' engines (i.e. creating more stored energy?) would help in their  smooth running?.

Hope this may help in some way further down the track.

Cheers....
Collbee

Online Roger B

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Re: Hit and miss engine
« Reply #6 on: March 28, 2021, 08:05:48 AM »
Excellent  :praise2:  :praise2:  :wine1:

That's a good prototypical speed  :ThumbsUp: When you start on hit and miss you may need to do something to increase it (or specifically the size of the bang). To allow the hit and miss governing to work the engine should be capable of 'running away' off load so the speed can be restrained by the governor and be firing continuously at full load.
Best regards

Roger

Offline Zephyrin

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Re: Hit and miss engine
« Reply #7 on: March 29, 2021, 08:24:05 AM »
very nice model, and good runner !
the most delicate point with the model, is to obtain a slow speed for a realistic rendering, the rpm has to be about the same as the original, in spite of its reduced size ! 

Offline Richard-Vanderpol

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Re: Hit and miss engine
« Reply #8 on: March 31, 2021, 11:46:49 AM »
i love it