C.D.I. conversion for the Mac engine

gyromike

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Oct 29, 2003
Messages
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Location
Abbeville, Louisiana
Aircraft
Bensen B8MG
Tuesday I installed a CDI conversion on my Mac engine. This is Rick Whittridge's magneto conversion. I bought it from one of our chapter members who decided not to use it.

The installation was straightforward, and everything went according to the directions. I had also spoken to Rick on the phone, and he was very helpful.

All of the internals in the mag housing are finely machined, and the CDI is potted to protect against vibration.

I mounted the coils on the top of my upper engine mount, taking care to leave clearance between the prerotator cable and the pushrod tubes. The CDI unit mounts between the mag housing and the upper engine mount. And the mag housing goes...well it goes where the old mag went. :)

I am using Champion D-9 (509) plugs from the local carquest @ $2.24 a piece vs. $15 a plug for reconditioned fine wire aircraft plugs, and stainless core 7mm ignition wires with 90º boots on the plugs and straight boots into the coils. The plugs are gapped @ .030".

Timing was a snap using Rick's instructions too. I set it to 21º BTDC.

After wiring the switch, and tidying up the wires, we rolled it out side and it fired on the 3rd pull of the prop. No stumbling, no spitting, it just started. Several times.

Yesterday, I took it up for a late afternoon flight and it ran like a top. Same thing for today. The highest CHT that I saw with the retarded timing is right at 400º on climbout, and that drops quickly on power reduction.

The idle is smoother and I was able to reduce the idle speed a little, but since my TinyTach bit the dust I'm not sure of the RPM's.

I'll attach a couple of pictures of the installation.
 
Re:C.D.I. conversion for the Mac engine

CDI picture 1.
 

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Re:C.D.I. conversion for the Mac engine

CDI picture 2.
 

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Hey Mike , Your installation looks good. Pretty straight forward to install.Glad to see another MAC up & running with my system. I hope you enjoy the mag as much as I do. It`s nice to know you don`t have to worry about when the old point mag might give you a MAC ATTACK! Enjoy & feel free to call anytime for your Mac needs. I `m dedicated to keeping the Mac ALIVE!
 
It gets a big thumbs up from me, Rick.

It hasn't taken more than four pulls on the blade to start it, usually just three.

And when it fires...it's running!
 
Mike: Nice setup. I wish I had that on my Mac years ago. It was a rush flying that thing. Times I never will forget..especially the attacks.
 
Nice gyro can we have a picture of the gyro? :D
what kind of paint did you use to paint your Mac? :confused:
I am planning to paint mine.
 
Stan,

I've never had a Mac Attack (siezure) yet, although my Mag had given me some trouble, and I had a little carb trouble occasionally (trash). Mainly the magneto though. I did break a ring once, but it still flew. I just had low compression on one cylinder.

I run it a little rich, and use Amsoil synthetic 2-stroke oil.
8 oz. Amsoil to 5 gallons of AvGas.

-------------------------------------------------------------------------

Jose,

go to the Instrument Pod thread that John Stevens started:
http://www.rotaryforum.com/forum/showthread.php?t=631&page=1 , and my gyro is the first picture that John posted.

I used high temperature engine paint on my engine case:
Dupli-Color Engine Enamel
Daytona Yellow - DE1642
http://www.duplicolor.com/products/engine.html
 
Did you took out the cilinders to paint? what is the all prosidure of painting?
is my first time painting a engine. :confused: Did you pain your gyro with the same paint?
 
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Jose,

I disassembled the engine and rebuilt it myself, so I painted the engine case seperate from everything else.

I think I used black exhaust header paint on the cylinders, and then baked them to cure the paint. I can't remember right now.

My instrument pod is painted with Yellow paint, but I don't remember the brand. Maybe Krylon. I just used whatever was closest in color but it is not an exact match with the rest of the frame.

The frame is powdercoated yellow, and the cheek plates, cluster plates, angles, etc., are powdercoated Gloss Black.

The instrument panel is powdercoated in black crinkle-coat.

I had the powdercoating done locally for about $500.
 
Mac Mag

Mac Mag

Rick Please send me Info on your CDI system.Do I need a battry and a gen.
 
Ola Jose Do you mean you have one for sale,if so how much.
 
Hola! No, I don't have one for sale. I have mine on my Mac . Belive me is worth to buy it.
 
CDI conversion for the Mac engine

CDI conversion for the Mac engine

Amen!!!!! if you aint got one get it!!! its every bit as good as everyone sezs!!

I am fairly new on this forum, the infomation you get here is priceless!! Example is Rick replyed to my post on cowls showing a picture of his engine without the cowls, so I took mine off it has already saved me a lot of time inspecting the engine, but the kicker is while looking at the engine I could see the piston pin with the hollow end was visible through the exhaust port. I remembered in the Bensen manuel it needed to be turned opposite when you turned the cylinders exhaust ports up, I had presumed it was right when I bought the engine. There is a lesson in that somewhere, anyway got it all back together and it runs perfect it even IDLES! but without this forum I could have had a ruined engine or worse. Thanks everyone!!!!!!
 
uprdown

uprdown

Hey Dan I must have missed that thread.I'd like too know,do they go up or down?Also I'm told my 72HP Mac.never had Cowls,I was about to start making them.If I do'nt needem,that's great :D
 
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