Engine - air compressor conversion?

[smiley]

Or keep it really simple and buy four of these, ( Spark plug "air compressor")
stick them in the spark plug holes and be done with it. If I remember correctly, they have one way valves that allow intake of air on the downstroke and close on compression out the hose. I have one in the barn and will check it today. Then you can close off the manifold any way you want. Even stuffing rags down it--- until they worked through to the valves--which could make for some interesting noises and air output.

I did check out the spark plug compressor that I have and it does have a one way valve that allows air intake on the downstroke and another that opens on compression and prevents return from the air tank, tire or whatever you're pumping up. I don't know what the actual volume of air they will put out, but the one I have was purchased to blow up John Deere A rear tires, and it did that in a hurry off my '69 Ranchero 302.

as stated by Mace Canute [Quote
Re: Engine - air compressor conversion?
Regarding the "spark plug air compressor"...the engine piston stroke is used to operate a simple diaphragm by the action of suction & compression. The air that goes into the tire is drawn from atmosphere and the unburnt fuel from the cylinder goes out the exhaust pipe. --Quote}

It has a hole slightly smaller that the diameter of the plug (close to 1/2") so as observed by Philip8n, wouldn't put out as much air as sucking it through the manifold. It definitely isn't heavy duty enough to stand up to sustained use, but it would be easy to use 2 commercial one way valves plumbed into the spark plug holes. I'm sure that unless the intake manifold was blocked off, you'd still get a slight fuel charge also.

 

[zmoz]

They also had automatic variable speed control to control capacity and automatic unload when discharge pressure was reached. How is you homemade machine going to do this?

Cruise control. As for when peak pressure is reached, I could probably adapt one of the throttle controls used on small engine air compressors. They work just like a normal air compressor switch except they pull on the throttle cable instead of an electric switch. Or for that matter, just make sure I have multiple blowoff valves...

 

[PHILIP8N]

Cruise control. As for when peak pressure is reached, I could probably adapt one of the throttle controls used on small engine air compressors. They work just like a normal air compressor switch except they pull on the throttle cable instead of an electric switch. Or for that matter, just make sure I have multiple blowoff valves...

Cruise Control! I would like to see that (good luck)! Please share your detailed design! The Grimmer-Schmidt compressors use a system called pace-air-control. When the set maximum discharge pressure is reached, a back pressure regulator sends an air signal to the air cylinder controlling the throttle on the carburator to tell it to slow down. At the same time it unloads one compressor valve. Both of these actions decrease capacity (and pressue in an indirect way). If pressure continues to rise, then the pace-air system will continue to slow engine and unload more compressor valves until compressor is completely unloaded. If pressure drops, the opposite happens. The engine will speed up and compressor valves will be loaded one at a time until compressor is at full speed and all 4 valves are active. How much scfm do you guys need? Would it not be simplier to buy or make a 5hp to 9hp belt driven wheel barrow consrtuction type compressor? You could even drive a used 2 cylinder compressor off the PTO. I think it would be safer than converting a V8 engine. Whatever you do, protect all possible areas of pressure isolation with a properly sized safety relief valve. Philip.

 

[zmoz]

How much scfm do you guys need? Would it not be simplier to buy or make a 5hp to 9hp belt driven wheel barrow consrtuction type compressor? You could even drive a used 2 cylinder compressor off the PTO. I think it would be safer than converting a V8 engine.

But where's the fun in that? No, I don't need nearly that many CFM, that's why I'm not too concerned about the throttle control. It doen't need to be terribly efficient for my useage.

I have been thinking about making a small single cylinder(engine) compressor, but, a good 5-9hp engine is going to cost $300+. The compressor pump is $200+. Then add the belt and pulley and throttle control and....

I already have the 350 just taking up space. ($0) I probably couldn't sell it for much more than $400. Then I don't need a belt drive, or a compressor. Then there's the fact that I just happen to be a fan of V8s....

Right now I'm waiting to find out how much a custom camshaft would cost. That may be the deciding factor here.