I am finishing a Holt 4 cylinder 4 cycle engine and I need some small valves. The stem dia should be around .124. The length is about 1.375 long. Head dia should be about .4373. Can be metric but close to desimal size. Has anyone got any loose valves out of any engine about this size? I will machine heads to fit valves I find. Thanks Capt,n

Happen to have a loose valve from a Magnum 30. It measured as follows . . . .

Stem .117
length .756
Face .312

Intake and exhaust are the same

I have a ton of engines apart right now, these are the closest.

OS FS-91 Intake valve is 26.2mm(1.031" ) tall, 3mm(.118" ) stem, and 11.2mm(.441" ) face.

OS FS120 exhaust valve is 32.6mm(1.283" ) tall, 3.5mm(.138" ) stem, and 12.2mm(.480" ) face. The intake valve has a 14.2mm(.559" ) face.

Good luck.

gkmysz: Looks like that O.S. with the .480 face may be close. This engine is a low speed engine...no need for big dia valves. I will post a photo of the cylinder head. Even the .480 head may be to big for the 1.000 inch bore! I need a valve long enough ,looks like it may be a problem??? Keep the data coming. Thanks much.....Capt,n

Have you though of making your own? There has been a couple good threads in the last year on both the Miniture engine and Radial and rotary enging groups on Yahoo. Basicly a good piece of 1/2" drill rod for the stock and a lathe with a collet to handle the drill rod. Cutting the stems is easier if you make your final pass a very deep cut. You have more stock to support the stem that way. Then you are left with the project of groving the little stems, but a good collet in the lathe will make life easier. There is a guy that makes valves for the 1/6th scale P&W Wasp engine. They are a bit smaller than what you are asking for though. 3/8" head size and overall length of 20.3mm with a stem Diameter of 3/32". Check on the R_&_R_Engines group, in the files area and you can find some soruces for haveing valves, springs, and the like made.

The other group is Min_Int_Comb_Eng Also a good source of info.

Don

To buy ready maked valve can have problem with right length and diameter of valve stem when the valvediameter are right.

It is better to make own valve of stainless steel (no rust and extremely tough).
The valve diameter are calculated by valve lift, also are valvelift 1/4 of valve diameter. The formula: Valvediameter:4=valve lift. Find how high are valvelift in your camshaft in the 4 cylinder engine before you can make own valve with right valvediameter.

Motor boy: You are right in most cases...but the head has no guides in yet or the seat is not machined either. I should be able to make a pre-made valve fit easy. I got too many other parts to make. Besides I can get the springs and valve keepers to fit a stock made valves. Capt,n

Just thought I would post a couple of photos of the Holt 4 cylinder. I will run it on Glow fuel or Gas/Glow mix. I got the crank in to check fit. Capt,n

Forgive my ignorance. Never seen one of those before.

How is it cooled? Not air cooled is it? I see no fins on the cylinders.

Thanks

Rcpilet: I never seen a Holt engine before untill a person emailed me. I ended up buying the engine to finnish. It is watercooled. It may be too heavy for airplane use. But I could aways turn some finned aluminum cylinders whith steel liners, and make a air cooled version too. I guess some old-time aircraft was water cooled. Not sure of the names might be!! Anyway it sure is fun getting any engine finnised up and see it run. I read one guy has run his on glow fuel. Thats what I may try first. Best Regards,Capt,n

The water cooled aircraft engines maked before second war had welded thinn steel sheet as water jacket around the cylinder and there was not dismantable cylinder head also the cylinder head was welded to cylinder, let us say the cylinder was complete with cylinderhead and water jacket to save weight. Crank shaft and cam shaft was hollowed, the crankcase was maked light as possible.

Your engine are stationary engine or marine engine, best as slow running engine, maybe not more than 1000-1500 rpm. Puf-puf-puf..

As John has said earlier, Holt was a predecessor to the Caterpillar tractor company

I think it would work good in a boat...then I could use it to pull my fishing lures along the shore of Lake Michigan. Capt,n Seen it done it works...