Original Posted By: "DJ Vegh"
Subject: Pietenpol-List: Hegy prop for a Corvair, and carb questions.I have a chance to buy a Hegy prop for a Corvair engine for $500. Don't have the stats for the prop, other than it has never been installed. I've been toldthis prop is the correct pitch, etc. and perfect for a Corvair pumping out 100+ horsepower.Does $500 sound like a fair price? I'm not familiar with pricing and props for a Corvair. I've heard that Hegy (builder from Marfa, TX).Lastly, I'm contemplating installing a Corvair in a Piet. I was impressed with the Corvairs I saw flying at Brodhead this year. But, having had a bad experience with a Mosler 82X a few years ago, I'm reluctant to go back to a carengine.What I didn't like about the 82X (souped up VW with Scat Racing Heads, beefy crank and a hot camshaft) was a funky carb set up, no mixture control and ultimately NO RELIABILITY. In addition, the Mosler could not produce any powerat 2,800 RPM and it really needed a reduction drive in order to get the power-band and prop working where they both were happy. (I tried a number of differentprops, and 2 different 82X engines, but the problem was with the Mosler and funky non-aviation carb.Is there a faithful carb with mixture control for the Corvair set up? What about dual mags for a Corvair?Thanks.S.B. ________________________________________________________________________________
Pietenpol-List: Hegy prop for a Corvair, and carb questions.
Re: Pietenpol-List: Hegy prop for a Corvair, and carb questions.
Original Posted By: N321TX(at)wmconnect.com
you will need more info before you can decide on that prop.... someone tellingyou it is the perfect prop for a 110+ hp 'Vair means nothing. Yeah.. it maybe the perfect prop for a Corvair.... a 54X60 is a great prop for a Corvair.it will absorb the power nicely.. but only for a plane that will cruise at 120+mph.It would be useless on a Piet. I doubt it would even get airborne withany level of safety. Also remember it needs to be a reverse direction prop(unless you go with a reverse camshaft)You want a prop that's gonna let you cruise around 75-80 or so at about 2400rpm. This is a ballpark figure as I have no direct experience... it just seemsabout right to me. You'll want a diameter around 62 to 66" with a pitch around36 to 30" respectively. again... ballpark numbers$500 sounds good. I paid $550 shipped to my door from Tennesee prop. They custombuild the prop to order. They use 1/16" laminations. There are 48 of them.Most prop makers use 1/2" laminations. more laminations means a stifferstronger prop..... and some may think a more beautiful looking prop. You'llalso want to make sure the prop is through-bored to allow the William Wynne safetyshaftto clear.Do you have William Wynne's Corvair Conversion manual?DJ ----- Original Message -----
you will need more info before you can decide on that prop.... someone tellingyou it is the perfect prop for a 110+ hp 'Vair means nothing. Yeah.. it maybe the perfect prop for a Corvair.... a 54X60 is a great prop for a Corvair.it will absorb the power nicely.. but only for a plane that will cruise at 120+mph.It would be useless on a Piet. I doubt it would even get airborne withany level of safety. Also remember it needs to be a reverse direction prop(unless you go with a reverse camshaft)You want a prop that's gonna let you cruise around 75-80 or so at about 2400rpm. This is a ballpark figure as I have no direct experience... it just seemsabout right to me. You'll want a diameter around 62 to 66" with a pitch around36 to 30" respectively. again... ballpark numbers$500 sounds good. I paid $550 shipped to my door from Tennesee prop. They custombuild the prop to order. They use 1/16" laminations. There are 48 of them.Most prop makers use 1/2" laminations. more laminations means a stifferstronger prop..... and some may think a more beautiful looking prop. You'llalso want to make sure the prop is through-bored to allow the William Wynne safetyshaftto clear.Do you have William Wynne's Corvair Conversion manual?DJ ----- Original Message -----
Re: Pietenpol-List: Hegy prop for a Corvair, and carb questions.
Original Posted By: N321TX(at)wmconnect.com
forgot to address a couple other questions in your emailas for concern about using a Corvair... just let that concern fade away. TheCirvair is practically an Aero engine. It's closer to an Aero engine than anyother auto engine is... period. In about 8 months I'll have mine flyingand you can come out and fly it/see it anytime you want.Dual mags can be done on a Corvair. I've seen it. It takes a tremendous amountof re-engineering and machining. In my opinion it's not worth it. If you convertthe engine to William Wynne specs you will have dual redundancy in thecomponents of the ignition that fail.... the coil and points. I have dual pointsin my distributor and I have 2 coils connected by a solid state auto coilswitch. If one coil should fail the switch automatically changes to the othercoil. Points never fail suddenly. It's usually a slow process that can be detected.2 plugs are not needed in a Corvair like they are in an Aero engine. Look at anAero engine..... large displacement... there's alot of volume to ignite. Youneed 2 plugs just to ignite and burn all the fuel... that's why a mag checkgives you a drop in RPM. there's raw fuel not being ignited by the 2nd plug.Now in a Corvair where the volume is less there's just no need for a 2nd plug.Even if you did have dual mags with 2 plugs in each cylinder I doubt a mag checkwould show much of an RPM drop. Sure there's an element of redundancy with dual mags but you are getting the sameredundancy with dual coils/points. The point of failure is usually not sparkplug wires or the spark plugs themselves. And of course... there's the needfor a battery to power the ignition with coil/points. yes.. if the batterygoes dead so does the engine, but that's not likely to happen and there are waysto add in redundancy there if desired.There are thousands of proven flight hours with Corvairs built to WW specs. As for carbs.... you can't go wrong with a Marvel MA3-SPA. I am using a StrombergNAS-3A1 with mixture control, but there is large debate on how effectivethe mixture really is on that carb.DJ ----- Orginal Message -----
forgot to address a couple other questions in your emailas for concern about using a Corvair... just let that concern fade away. TheCirvair is practically an Aero engine. It's closer to an Aero engine than anyother auto engine is... period. In about 8 months I'll have mine flyingand you can come out and fly it/see it anytime you want.Dual mags can be done on a Corvair. I've seen it. It takes a tremendous amountof re-engineering and machining. In my opinion it's not worth it. If you convertthe engine to William Wynne specs you will have dual redundancy in thecomponents of the ignition that fail.... the coil and points. I have dual pointsin my distributor and I have 2 coils connected by a solid state auto coilswitch. If one coil should fail the switch automatically changes to the othercoil. Points never fail suddenly. It's usually a slow process that can be detected.2 plugs are not needed in a Corvair like they are in an Aero engine. Look at anAero engine..... large displacement... there's alot of volume to ignite. Youneed 2 plugs just to ignite and burn all the fuel... that's why a mag checkgives you a drop in RPM. there's raw fuel not being ignited by the 2nd plug.Now in a Corvair where the volume is less there's just no need for a 2nd plug.Even if you did have dual mags with 2 plugs in each cylinder I doubt a mag checkwould show much of an RPM drop. Sure there's an element of redundancy with dual mags but you are getting the sameredundancy with dual coils/points. The point of failure is usually not sparkplug wires or the spark plugs themselves. And of course... there's the needfor a battery to power the ignition with coil/points. yes.. if the batterygoes dead so does the engine, but that's not likely to happen and there are waysto add in redundancy there if desired.There are thousands of proven flight hours with Corvairs built to WW specs. As for carbs.... you can't go wrong with a Marvel MA3-SPA. I am using a StrombergNAS-3A1 with mixture control, but there is large debate on how effectivethe mixture really is on that carb.DJ ----- Orginal Message -----
Re: Pietenpol-List: Hegy prop for a Corvair, and carb questions.
Original Posted By: DJ Vegh
I different with your failure of points. They have and they do break... suddenstop! ----- Original Message -----
I different with your failure of points. They have and they do break... suddenstop! ----- Original Message -----
Re: Pietenpol-List: Hegy prop for a Corvair, and carb questions.
Original Posted By: cgalley
well... I've never heard of a sudden points failure.... but hey.. Magnetos havepoints too. In any case there are 2 sets of points in my distributor so redundancyis there. ----- Original Message -----
well... I've never heard of a sudden points failure.... but hey.. Magnetos havepoints too. In any case there are 2 sets of points in my distributor so redundancyis there. ----- Original Message -----