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brian Rupnow
07-22-2014, 12:43 PM
I have a question about side valve engines. I have looked at a number of pictures of side valve engines, and they seem to fall into two categories. One is as per the Philip Duclos Gearless engine, where the cylinder is a plain bore separate part and the combustion chamber is actually in the head, which bolts to the top of the cylinder. The valve cages, seats, and housings bolt onto the outside of the head and are connected to the combustion chamber in the head through passages drilled through the sides of the head. The piston does not travel up into the head, but stops flush with the top of the cylinder.
T he other type, (and I'm really not sure about this) seem to have a plain bore cylinder, then a separate piece with the combustion chamber and valves buried in it bolted to the top of the cylinder, and then a flat, rather featureless (except for sparkplug hole and cooling fins) head bolted to the top of this intermediate piece.
It kind of LOOKS like the piston would have to travel up part way into this intermediate piece, but I just can't imagine a bolted joint that the piston and rings would have to travel over. (see picture) ----Or--is it possible that there is a cast iron liner that fits down through the intermediate piece and the cylinder so the piston can travel all the way without passing over a joint? Who can set me straight on this.----Brian
http://i307.photobucket.com/albums/nn294/BrianRupnow/BrianRupnow015/sidevalveengine001_zpscd16662f.jpg (http://s307.photobucket.com/user/BrianRupnow/media/BrianRupnow015/sidevalveengine001_zpscd16662f.jpg.html)

topct
07-22-2014, 01:27 PM
I can't imagine there being a joint that the piston would travel over. My guess is there is a liner down through the section with the valves and a combustion chamber in the head including a space to relieve the opening valves.

Interesting little engine. Looks like a sight glass to see the sump level and maybe a little oil pump?

Another edit. If the rings were located down on the piston to be below the joint at TDC that could work also.

dp
07-22-2014, 01:37 PM
All single cylinder engines I've ever worked with are a variation of this simple design:

https://www.flickr.com/photos/15794235@N06/5245356917/?rb=1

That includes 45" Harley-Davidson V-Twins, single cyclinder Briggs & Stratton engines, and my 1955 Cushman. All were flat head designs. I also had a 1953 Plymouth that had a 6 cylinder flat head with the same basic layout.

chipmaker4130
07-22-2014, 01:47 PM
Why couldn't that intermediate piece be the combustion chamber? If compression ratio is an issue, the head could easily be made to protrude into that area.

topct
07-22-2014, 01:56 PM
Or, if the top of the cylinder was made to extend into that center section.

chipmaker4130
07-22-2014, 01:58 PM
Yeah, I think that's what the others are saying about the sleeve. Same idea but in your case it would be integral with the cylinder, right?

topct
07-22-2014, 02:06 PM
Yeah, I think that's what the others are saying about the sleeve. Same idea but in your case it would be integral with the cylinder, right?

Cylinder/sleeve one piece.

dp
07-22-2014, 03:09 PM
There's a Webster plan set here that shows a valve block separate from the head and cylinder and where the cylinder slides through the block.

http://www.john-tom.com/html/ICEngines.html

Correction: Once I got the zip file downloaded and had a look at the PDF I see the valve block is attached to the cylinder head which is deeply recessed and into which slides the cylinder. The cylinder is ported to allow access to the intake and exhaust.

brian Rupnow
07-22-2014, 04:54 PM
The only major difference I see between the engine in this link that DP posted and the engine I might consider building is that on this engine the round cylinder and the part directly above it which houses the valves is all whittled from one solid chunk. I could do that--but it would be a bit of a pig to cut the cooling fins on.--Wouldn't be able to use the lathe.--At least not on the part above the round cylinder.--Of course the round part of the cylinder is down towards the bottom of the piston skirt, so probably doesn't need fins on it anyways.
https://www.flickr.com/photos/15794235@N06/5245356917/

kf2qd
07-22-2014, 10:53 PM
It is just a basic Flat Head engine. THE top of the block was flat, the piston at TDC was even with the top of the block and the combustion chamber was in the head, had recesses for the valves and tended to have a taper over the piston.
Commonly called an L Head

A variation was the F Head where the exhaust have was in the block and the intake was in the head. Intake manifold was part of the head.

J Tiers
07-22-2014, 11:58 PM
It is just a basic Flat Head engine. THE top of the block was flat, the piston at TDC was even with the top of the block and the combustion chamber was in the head, had recesses for the valves and tended to have a taper over the piston.
Commonly called an L Head

A variation was the F Head where the exhaust have was in the block and the intake was in the head. Intake manifold was part of the head.

Yes.

Most small Briggs and so forth are the very same design. The fins are perfectly fine for casting, , yeah, not so good for cutting.

krutch
07-24-2014, 07:34 PM
Most likely the piston rings won't cross the "joint". If the piston actually enters the head portion it is at it's top dead center and the rings should be below the top of the cylinder.
On some "hopped up" Harleys the piston top does clear the cylinder top but no ring will be close enough to cause a problem. That a piston enters the head is for higher compression ratio. Such a piston may need to have a pocket milled into its' top for valve clearance. Side valve engines usually are a low compression unit. Shaving the head is the normal way to increase their ratio. Some also shave the cylinder top.