Author Topic: Ford Wyvern type petrol engine  (Read 3245 times)

Offline steam guy willy

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Re: Ford Wyvern type petrol engine
« Reply #45 on: May 18, 2019, 12:42:59 AM »
Hi All , I have now completed the wiring and tightened up all the nuts and bolts... I have made a device to start the engine  By utilising a modified Starret hole saw that is inserted in the small pulley. I have put some petrol in the tank and have turned it over quite a few times but the engine has not started. I don't know anything about small carbs and what the settings of the lever and the screw down part is. Are there any instructional vids or any other detailed info on the web or from your own experiences ??? here are a few pics of the carb etc...

Willly
« Last Edit: May 18, 2019, 02:22:17 AM by steam guy willy »

Offline Jasonb

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Re: Ford Wyvern type petrol engine
« Reply #46 on: May 18, 2019, 07:02:21 AM »
These engines don't need much fuel so you want the mixture quite lean, probably screw that top screw down to weaken the mix. Grahams method of checking the mixture by holding a flame a couple of inches from the open exhaust port is a good way to judge mixture with petrol or gas, big orange flame indicated a rich mixture as you turn the engine over by hand.

I'd also be looking at that plug wiring as it could easily be shorting to the exhaust elbow, try turning it over in a darkened room and see if you can see the spark jumping across where it should not.

Offline Alyn Foundry

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Re: Ford Wyvern type petrol engine
« Reply #47 on: May 18, 2019, 11:58:23 AM »
Good morning Willy.

From my point of view you've reached the " best " part of the restoration, getting them running!

As Jason has pointed out please check to make sure you're not loosing the HT and you've got a nice " fat " spark at the plug. I'd also suggest setting the contact maker to start just before or on TDC, compression stroke.

Propane has a very narrow band of mixture with air for combustion but Petrol/Gasoline is way more forgiving. The carburettor has a " fixed " jet, check it's not blocked. I'd forgotten that there wasn't a means of altering the fuel metering rate, just two controls for air. The top control effectively throttles the air into the cylinder whilst the lower lever is there to create a partial vacuum to draw the fuel off the jet.

To start with I'd suggest almost closing the bottom control and set the top to halfway open. Hopefully you'll get a few Black smokey bangs ( choked condition ) whereupon you can start to gently open the air
( bottom ) lever and the engine should pick up speed.

I can't stress enough the delicacy needed when " playing " with small power engines, a little does a lot at this size. Once the engine is running you can then " advance " the ignition to a few degrees BTDC for a cleaner and more powerful power stroke. Please bear in mind that with a fixed jet carburettor the engine can " race away " very quickly that's why they fitted the top air control !

I hope I've been able help? What you're doing now is what I did many times over the years whilst exhibiting my large collection of vintage stationary engines.

Cheers Graham.

Offline Roger B

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Re: Ford Wyvern type petrol engine
« Reply #48 on: May 18, 2019, 12:45:30 PM »
Have you been through the basics?
'Bouncy' compression.
Valve sequence approximately correct. Inlet valve opens around top dead centre, closes a little after bottom dead centre. Compression stroke. Exhaust valve opens a little before bottom dead centre, closes around top dead centre.
Good spark around top dead centre on the compression stroke.
Best regards

Roger

Offline steam guy willy

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Re: Ford Wyvern type petrol engine
« Reply #49 on: May 19, 2019, 01:32:48 AM »
Ok I have tried the engine again but to no avail ...I then tried to see if the engine valves were performing correctly by putting a balloon on the exhaust pipe assuming it would inflate ?? however it didn't !! however when i tried the engine in 'reverse' ie turning the top of the flywheel anti clockwise  top towards the engine ,it did inflate the balloon  ??!!  however when i went to reattach the carb i managed to break the inlet manifold part  :( :(  so i will have to repair this by silver soldering ...it is not broken in two so that might work ?...so ...more work tomorrow... Also more bad news .....Grumpy cat has died .....
« Last Edit: May 19, 2019, 01:42:20 AM by steam guy willy »

Offline RayW

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Re: Ford Wyvern type petrol engine
« Reply #50 on: May 19, 2019, 09:19:28 AM »
Hi Willy,As has been mentioned already, you only need the slightest amount of gas. If you can hear gas at the end of the gas pipe, you probably have too much. One thought, are you sure that the ignition is set to fire on the correct stroke, ie. at TDC on the compression stroke, not on the exhaust stroke?


Ray

Offline RayW

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Re: Ford Wyvern type petrol engine
« Reply #51 on: May 19, 2019, 09:35:05 AM »
Hi again Willy. This is the link to my YouTube video showing how to use a candle to check the gas mixture.
Ray

Offline Alyn Foundry

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Re: Ford Wyvern type petrol engine
« Reply #52 on: May 19, 2019, 11:09:49 AM »
Good morning Ray.

Whilst I have advocated the use of a burning candle to check the mixture of a gas engine, I wouldn't recommend doing this with a Petrol version. For a couple of reasons.

Firstly and most importantly the safety issues. Being a liquid fuel with an overly rich mixture you could end up with a fire that couldn't be extinguished easily. It's easy with gas, you just turn off the supply.

Secondly, Petrol engines are really quite forgiving where mixture is concerned as the combustion bandwidth is very wide in comparison to Propane.

From Willy's description it would appear to be a " reverse rotation " ( to the norm ) with the flywheel wanting to be driven towards the cylinder rather than away from it. The engine could be re timed by dropping the sideshaft and following Rogers description from a couple of earlier posts.

Cheers Graham.


Offline RayW

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Re: Ford Wyvern type petrol engine
« Reply #53 on: May 19, 2019, 06:30:56 PM »
Quite right Graham.  My comments were specifically for gas engines, not petrol.
Ray

Offline steam guy willy

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Re: Ford Wyvern type petrol engine
« Reply #54 on: May 20, 2019, 01:49:09 AM »
Hi Ray and Graham  et al   The engine is now running ...!!!!!!!  Yea ...and it is designed to run ' backwards'  as per conventional engines  ?!!!  Thanks for all your help with this and i have put a video on Vimeo... here it is    .The split inlet manifold was mended ..i used some thin multi stranded copper wire wrapped around the break and silver soldered it all up . 
   

Willy
« Last Edit: May 20, 2019, 03:00:11 AM by steam guy willy »

Offline Jasonb

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Re: Ford Wyvern type petrol engine
« Reply #55 on: May 20, 2019, 07:25:39 AM »
Well done, it runs well for it's age and at a nice steady speed for a small engine.

Offline Roger B

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Re: Ford Wyvern type petrol engine
« Reply #56 on: May 20, 2019, 10:28:47 AM »
Nicely done  :praise2:  :praise2: The reverse rotation was a bit of a 'Gottcha' though  ::)
Best regards

Roger

Offline Alyn Foundry

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Re: Ford Wyvern type petrol engine
« Reply #57 on: May 20, 2019, 11:21:27 AM »
Yes indeed, well done Willy.   :)

Offline Admiral_dk

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Re: Ford Wyvern type petrol engine
« Reply #58 on: May 20, 2019, 11:31:00 AM »
Reverse running ...?.. compared to what ?

Most aero engines are running counter clock wise ...!...

Nice restoration Willy  :cheers:

Offline Jasonb

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Re: Ford Wyvern type petrol engine
« Reply #59 on: May 20, 2019, 12:58:55 PM »
Reverse running ...?.. compared to what ?

Most aero engines are running counter clock wise ...!...


99+% of opencrank engines run the opposite way to willy's eg top of the flywheel away from the cylinder

Ones with two flywheels could be said to run counter clockwise depending on which side you look at them from  :LittleDevil: