Valve timing, De Dion or Orient Single

[Bush Mechanic]

1906 Orient Buckboard 4hp single cylinder. Engine lacks power.

 

This is a friend's vehicle that I have been helping with, trying to resolve a 35 year ongoing problem that has existed since it was initially restored. I cannot find any technical specs for this Waltham Orient engine, but as it is a copy of a De Dion, I thought that perhaps someone may be able to direct me to specs, particularly the exhaust valve timing, for that engine. As 'Aster'? France, was involved in the company prior to this engine, perhaps it is a copy of their engine, which I believe was copied from the De Dion, anyway. This beast is a bit outside of my field, and I don't have much idea what timing these engines use. The exhaust may well be one tooth out.  Any ideas?

 

The inlet valve is vertical atmospheric, and we have tried a number of different strength home-wound springs, using the rule of thumb for tension of one lb at fitted length, for each ounce of valve/keeper etc. By doing this we have reduced the blow-back through the carb inlet, but the pundits think we have too much spring pressure. The carb is the original Waltham device for the engine, with a type of rotary vane which directs different proportions of the inlet air across the jet for mixture control. Or so it appears, to me. And it has a constant flooding problem, which we are yet to resolve, but I don't think that is behind the lack of power. There are a couple of cracks in the exhaust valve seat which concern me, but the consensus is that they will have minimal effect on power generated. On a smooth flat road you can coax 12 to 15 mph out of it, and it should manage twice that with ease. Climbing hills is out of the question.

 

Any leads on specs would be appreciated.   Thanks, Mick.

[cahartley]

Depending on the design of the cam......or lack of.......the exhaust valve COULD open slightly before bottom, at bottom, or slightly after BDC.

I would ignore those possibilities and try setting the camshaft so the exhaust valve closes slightly after TDC.

[JV Puleo]

Where does your rule of thumb for the atmospheric valve come from? I've worked on at least two cars with the original atmospheric valves in place (a Pope Hartford and an early Panhard) both had extremely light valve springs. What are you currently using for a spring rate?

 

j

[Bush Mechanic]

1 hour ago, JV Puleo said:

Where does your rule of thumb for the atmospheric valve come from? I've worked on at least two cars with the original atmospheric valves in place (a Pope Hartford and an early Panhard) both had extremely light valve springs. What are you currently using for a spring rate?

 

j

 

The rule of thumb came from the Smokestak site, for 'hit and miss' engines, and was the only info on the subject I managed to find. The original problem that I was attempting to address was fuel spraying out of the carburetor air intake on each stroke. Progressively stronger springs were tried, until that was achieved. The current spring was made from .047" piano wire, 7 turns in 1.5 inches free length, and from memory it was 1lb 9oz at fitted length. Appears to be opening about .060" cranking by hand, and there is a brass sleeve on the stem to limit it to 1/8" travel. I have chamferred the sleeve internally, as it was hammering, and binding on the valve stem, which is not ideal.

 

Personally, I think the valve timing needs to be checked, but I don't have a reference point. Currently the exhaust opens at 110 degrees ATDC and closes at TDC. My gut instinct is that it's a little early, but I would appreciate some input from people with experience with this type of engine. This is one of those situations where you come on board after others have been attempting a solution and failed. Not having assembled the engine yourself, you don't necessarily have complete faith in what has gone before.

 

Thanks for the interest,  Mick.

 

 

[JV Puleo]

I have some very early technical material I will take a look at. Somewhere, I think I have valve timing data for an early single cylinder DeDion engine. This will take a day or two... but you have captured my curiosity as well.

 

jp

[JV Puleo]

I'm not sure this will help much, the chart is a little newer than I remembered. It was compiled in 1908. The first chart is French cars, the second one is American cars. Again, a bit liter than I remembered. Nevertheless, it is probably closer to your period than anything you'll find on the internet.

 

 

[tom_in_nh]

On 3/28/2018 at 10:43 PM, Bush Mechanic said:

There are a couple of cracks in the exhaust valve seat which concern me, but the consensus is that they will have minimal effect on power generated.

What is the compression reading now?

Fix the valve seat cracks and recheck the motor's compression.

I suspect that is most of your issues.

Good luck.

Tom

 

On edit:

Is this the engine in question?

If so, is it possible to have one flywheel inoperable?

Edited April 1, 2018 by tom_in_nh
Added photo. (see edit history)

[Bush Mechanic]

4 hours ago, tom_in_nh said:

What is the compression reading now?

Fix the valve seat cracks and recheck the motor's compression.

I suspect that is most of your issues.

Good luck.

Tom

 Thanks Tom. A compression reading has not been taken. The engine appeared to have excellent compression, (but very little power), until it died suddenly on the road, with all compression gone.

Currently waiting for the machine shop to fit an insert. I too think that it will make a considerable difference. Unfortunately the owner's eyesight is not 100%, (like so many of us), and the cracking was not detected until the head was pulled this time. It may well have been there for some time. The valve was just beginning to burn, and the mating surfaces showed patches of what looked like mill scale. Due to the pressures of being involved in a rally at the time, it was reground and put back in. Much of the compression returned, but power was still lacking, and the car soon became un-driveable. The car has a good few spares, including a head, which I haven't seen yet.

Tom, in reply to your edit:-  Your excellent De Dion diagram is indeed very similar to the Orient engine, despite it being water cooled, rather than air cooled. The layout is basically identical. And as to your question re the possibility of a freewheeling flywheel on one side. I guess it is possible. They appear to be on a taper, most likely keyed. I would expect a good deal of noise if one had come adrift, but it is an interesting question. The old girl certainly shakes, but no doubt that is the nature of the beast. It starts easily, idles happily, and revs freely, despite the flooding. Now if it would just generate enough power...... It uses a friction disc transmission, which works well enough, once you get the hang of it. Driving it keeps you fairly busy, but more power would make it easier. Of course then you would have to learn how to stop. (Not it's strongest feature).

 

Mick.

Edited April 1, 2018 by Bush Mechanic
Reply to edit (see edit history)

[Bush Mechanic]

2 hours ago, JV Puleo said:

I'm not sure this will help much, the chart is a little newer than I remembered. It was compiled in 1908. The first chart is French cars, the second one is American cars. Again, a bit liter than I remembered.

 Thanks, JV, that makes interesting reading. Earlier than any that I have here. At first glance it appears to back up my instinct that the exhaust is timed a little early. Not sure if an atmospheric inlet valve, or indeed the single cylinder, would have any bearing on the exhaust valving required. 

 

Mick

[cahartley]

Everything matters.......

The idea behind the exhaust valve closing somewhat after TDC is the exhaust has a great deal of velocity so, also, inertia.

Holding the valve open a bit longer at the part of the cycle when the piston is standing nearly still for quite a number of degrees lets the cylinder purge better therefore making more room for the incoming mixture for the next power cycle.

In addition, with the piston already heading down the cylinder, it also eliminates pushing gases backward through the mixer so the cylinder gets supplied with the maximum explosive mix.

[Bush Mechanic]

Very nicely put, Mr Hartley.

 

Also, my concern over the strength of the inlet valve spring arose from envisaging it closing too slowly, allowing the incoming charge to begin to reverse flow back down the very long inlet tract during the early part of the compression stroke.  You could easily feel the wet charge blowing out of the carb on each stroke onto your hand held 3" away. It is perhaps possible that this effect was caused by the gas in the long inlet tube being shut off by the valve, compressing a little due to it's velocity, then rebounding back toward the inlet. I'm unsure if this is possible, but something caused it to reverse flow. In theory a stronger spring may possibly accentuate this effect, but it did cure the blow-back, and also brought about a noticeable increase in power

 

With the exhaust beginning to open at 70 BBDC, just 20 degrees beyond  the point of greatest piston speed, you are left with just 110 degrees of actual power stroke, out of 720 degrees total in a cycle. 

A 4 hp vehicle doesn't have a lot of excess power to waste on inefficiency. I feel sure that we will get it operating correctly eventually, and learn something along the way.

Edited April 1, 2018 by Bush Mechanic
clarification (see edit history)

[scotchyoke]

Good day all. Hope you have found your problem by now. I am very late at keeping up with posts. I would go back to the basics. Too lean a mixture will burn valves and seats. As for your lack of power there are only a few causes. As pressure is what makes the car go, the good preforming engine doesn't let the pressure escape through leaks. Well seated valves, no leaking gaskets and no tired rings are a MUST, on any engine. Little leaks extract a lot of performance.  Your tired valves, general leaks, worn rings or scored cylinder won't let you develop the cylinder pressure required to make any hill !! I believe if you address the above mentioned  conditions you will find the cause of the problem. As an owner of a 1903 Orient that little car in proper condition should run right along and definitely climb a hill. 

Then take a look at your timing. Peak pressure is reached before the end of the burning process, or about 15 degrees after top. Peak pressure before top center si bad news. Hope this helps if you are still searching for the problem. Best luck to you and others, Diane

[Bush Mechanic]

Thanks for the reply, scotchyoke.. The problem was not resolved, actually. I left on extended holidays, and the owner placed the Orient back in the museum. My notes reveal that  I did move the valve timing one tooth, which brought it right on the average timing for similar engines of the period, but didn't get a chance to follow up with any more testing. I agree that the engine needs a proper going through. It is now on the back burner, I guess.

[scotchyoke]

Dear Bush mechanic thanks for the response. Sorry it went back in hiding. I would have loved to know if you found the cause of the problem. It would drive me crazy until I got to the bottom. Also, great learning experience.  For future information. The intake atmospheric valve spring pressure should be 40 ounces to open. Just a note. Thanks again, Diane