Planetary gear drive for corvair, Duel plug heads

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don january

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I was looking at an old book I have: Auto engines for Exp. aircraft by Richard Finch 1986 era and in the back page 175 there is an add from Gyrodynamics selling prints to build your own planetary gear drive's and also corvair chain drive's. The company was based out of Redlands California. also there was plans for Duel plug corvair heads. As a corvair engine converter for my KR-2 I've never read or heard about these option from Mr. Wynne or Mr. clapp, leading supplier's of corvair conversions. Does any one know if they are still being used in aircraft ? or can plans still be purchased for the systems? I see that they were available for VW power plants also. It would be of great interest to me to learn the technique of Duel plugs on my motor. Don
 

Bill Clapp

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My understanding is that it was a simple planetary gear setup....Not sure if any were built or tested - they can have their own issues... heavy, harmonics, lubrication...and more. Would be neat to see one though....We are looking into a chain or belt drive to an offset shaft for another project...(skunk wrks....)
 

don january

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What about the Duel plugs for the heads I thought it was'nt possiable or way to much work
 

don january

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How about it WW your such a great corvair authority how about making the corvair duel plugged ? I'd rather have that for back up then a single distributor, 15 coils is'nt going to change a thing if that one plug gives up. Oh you have that much faith in that plug. I dont, your not that good
 

DaveP

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Dual spark plugs have been done on Corvairs. However, one must weigh the extra complexity and cost against the perceived gains. Spark plugs so very rarely fail that dual ignition into single plugs has proven itself to be as reliable as dual plugs. Dual plugs can cause lower compression due to the extra machining. If a bad oil ring if fouling one plug, won't it foul two? I saw one done that had a hall effect sensor firing an electronic module for a second set of plugs, a whole lot of time and money for a questionable gain.

Consider the reliability shown by the currently flying dual ignition into one plug Corvairs and make an educated choice.

Dave P.
 

don january

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plugs dont foul, ya right seen the pawnee come in many a times and the agwagon, eaa biplane should I go on. they foul just like my weedeater and sled and car. if there is a way to make my corvair safer rather it be oil ,spark, or fuel its the responsiblity of any supplier to open the doors to that modifacation to the buyer for there safty. sell the book stand behind the voice of the consumer, what the heck is the money for that hundred's put out?? if duel plugs been done then WY is there not an option for the builder?
 

don january

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is it that certain suppliers of corvair convesion found it more profitable to sell modified distributor's of there own design then to burden there customers with timely modifications on there engines? I would find it alot easier to drill an extra hole in my heads then to mail in a part and wait for a 4-5 week turn around for a part that only one person has a opinion on.
 

Bill Clapp

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Hey Don. The dual plug system would require another ignition source and wiring plus a way to distribute the spark. Modifying the distributor for dual points is rather straightforward. Most of the time is in resetting the advance curve to be usable for flight. I keep distributors on hand so if someone needs one I just ship it out and once they get it they ship theirs back. It's the least down time.
 

don january

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It sounds to me that atleast your willingness to send a part out and not be stressed about a core return is a very positive step towards customer satisfaction, rather your's and WW opinion on the ignition is satisfactory, time will tell. down time should NOT be a issue on a pleasure aircraft not for hire. and like your post states duel plugs require duel sources of the ignition components. Wy cant we just have one ignition system with duel plugs and a switch to control direction to plug?
 

akwrencher

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It sounds to me that atleast your willingness to send a part out and not be stressed about a core return is a very positive step towards customer satisfaction, rather your's and WW opinion on the ignition is satisfactory, time will tell. down time should NOT be a issue on a pleasure aircraft not for hire. and like your post states duel plugs require duel sources of the ignition components. Wy cant we just have one ignition system with duel plugs and a switch to control direction to plug?

The issue with that is that the ignition system is a single point of failure, whereas the plugs are, by definition, not. One plug failure is only a loss of 1 out of six cylinders. Much better to have duel ignition systems and single plugs than the other way around. If you really want duel plugs, I'm sure you could find a set of duel plug heads, or have a shop make you up a set. Only takes money. The fact that they are not readily available probably means that there is not enough people willing to pay extra for them. Keep in mind that not all plugs and ignition systems are created equal. Modern electronic ignition systems produce much hotter sparks than older points systems could because they don't have to worry about burning the points. That hotter spark helps keep plugs cleaner and reduces the chance of fouling. Running unleaded gasoline also helps, as lead tends to foul plugs on some engines. Don't take me the wrong way, I am all about redundancy and safety, but you have to pick your battles. It really comes down to your needs and comfort level I guess.
 

don january

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now that I read and think about the whole idea of duel plugs and ignition items, it seems that we as consumer's have only been lead down a path to believe one system is needed over the other. in my case it was Mr. Wynne and his writings on corvair conversions. but unfortunatley as of to date as a manual owner of Mr. Wynne I have not been contacted and no effort has been made to answer my questions
 

don january

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akwrencher: one morning I pulled my father out of a downed pawnee to find out later that not one but 2 plugs on his engine failed. I dont know your air time but I've seen it first hand. If as a group we can work out and reach a safe long lasting cure for engine failure due to ignition, then as a forum we accomplished somethink great. Don
 

Bill Clapp

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I am less concerned about a plug failure than a distributor failure. I've flown on five plugs and can maintain altitude - with my planes. I'm thinking more about the fact that some countries require dual ignition so am thinking up a drive system that runs of the crank or electronic to drive a second set of small plugs on a new head design. That's all down the road....
 

ekimneirbo

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I am less concerned about a plug failure than a distributor failure. I've flown on five plugs and can maintain altitude - with my planes. I'm thinking more about the fact that some countries require dual ignition so am thinking up a drive system that runs of the crank or electronic to drive a second set of small plugs on a new head design. That's all down the road....
That is something I have been thinking about too. I like the idea of a crank trigger or even a computer controlled multiple coil setup. MSD makes a Universal Crank Trigger (#8655) setup that can be set up to work with 6 cylinder engines. I know there are dual plug heads that individuals have modified, so it is doable ....just not sure how easy the placement of
the sparkplug holes would be. I see nothing wrong with dual plugs if its a reasonably easy modification. Its probably beyond the scope of most builders though without some machine shop help. Still I think its worth some consideration rather than dismissing its usefulness. Again, just an opinion. I know one of the main things with the Corvair movement is keeping costs low.....so if it doesn't need fixing it may be a moot point.
 
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ekimneirbo

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My understanding is that it was a simple planetary gear setup....Not sure if any were built or tested - they can have their own issues... heavy, harmonics, lubrication...and more. Would be neat to see one though....We are looking into a chain or belt drive to an offset shaft for another project...(skunk wrks....)
Back when I believed that an LS Chevy needed a reduction drive, I bought a Geschwender and a bunch of books/reference material on chain drive. Decided that the Geschwender was too heavy and expensive for my project and sold it. I still have the books if you think they might be of interest to you. They are older books and obviously not directed at airplane applications......but they explain a lot of basic information
on selection and application and even power limits. Probably a good six inches of knowledge there.
IMG_0095.jpg
 
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ekimneirbo

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IMG_0104.jpg
Back when I believed that an LS Chevy needed a reduction drive, I bought a Geschwender and a bunch of books/reference material on chain drive. Decided that the Geschwender was too heavy and expensive for my project and sold it. I still have the books if you think they might be of interest to you. They are older books and obviously not directed at airplane applications......but they explain a lot of basic information
on selection and application and even power limits. Probably a good six inches of knowledge there.
View attachment 39181
For some reason it wouldn't let me add these pictures on the first post, so I'll try again. IMG_0097.jpg
IMG_0100.jpgIMG_0103.jpgIMG_0101.jpg
 
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Wanttaja

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I spoke to an auto-engine converter years ago about the lack of dual plugs. He said modern electronic ignitions generate a much "hotter" spark and they don't tend to foul. Spark strength not affected by low RPMs, like a magneto is.

I don't think I've had plug problems in a car since ~1982.

Ron Wanttaja
 
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