Timing a vacuum engine... flame eater

[rlukens]

I'm still stewing over which type valve arrangement to design into a flame eater.
Regardless, common to all is valve timing. Is there a consensus on timing and duration? I assume a crank provides adequate "ramp" vs. a complex cam?
Tia
Russ

 

[fcheslop]

This site has some info
Around 120 to 140 degrees duration or lift
http://ridders.nu/Webpaginas/pagina_ervaringen_tips_happers/ervaringenhappers_frameset.htm

 

[Brian Rupnow]

Rlukens--This is the cam used on the Senft "Poppin" engine. It is connected directly to the crankshaft. When the roller is riding "up" on the cam, the valve is closed. When it isn't up on the cam, the valve is open. There is a spring which keeps the roller in contact with the cam. The instructions say to set it up so that the valve closes completely when the crankshaft is 45 degrees before bottom dead center for clockwise rotation.---Brian

 

[rlukens]

Thanks Brian. That's exactly the info I was looking for. I still wonder if a crank provides the save performance. It would be interesting to see the lift of a simple crank compared to the profile of the cam. That look like something a guy with your computer skills could show with an overlay ... hint, hint.
Russ

 

[Brian Rupnow]

Thanks Brian. That's exactly the info I was looking for. I still wonder if a crank provides the save performance. It would be interesting to see the lift of a simple crank compared to the profile of the cam. That look like something a guy with your computer skills could show with an overlay ... hint, hint.
Russ

I'll do it but I'm not exactly sure what you mean. The large radius minus the small radius gives you the lift. If you can explain what you want better or put up a sketch, I'll do it.---Brian

 

[Brian Rupnow]

RLukens--I threw you a curve ball on that cam drawing. I have changed it from what it was before.---Brian