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GPU plugs

I use Champion Plugs only. I just seem to always have good luck with them. In a completly stock low compression motor a D-18 is a good choice because it is a little hotter. Most commonly a UD-16 is used. D-16 will also work fine. If you have a high compression motor then go with a D-14.
 
Randyc, I use Autolite 386 plugs gaped .018. If you do a search you should find quite a series of plugs and why people like the ones they recommend. The most important thing I found is to make sure the magneto is in perfect working order. My current boat had a flooding problem according to the previous owner. He installed a shutoff for the fuel line and had a long procedure for shutdown to make sure it didn't flood. I had a certified shop rebuild the magneto and the fuel problem was gone. The mag just didn't have enough spark to ignite the fuel in the cylinder.

After you get the magneto rebuilt by a certified shop, buy a new harness from Mike Thurman. Trust me, that mag is really important. Oh, my GPU is the PE-150, but I use the Autolite 386 on my O-320 Lycoming too. Also, don't forget to throw away the plug washer and used aircraft plug copper washers.
 
Thanks for good words again Des Moines... I do more than just make wire sets. The board member Arkie who you recommended to me needed a wire set for an old outdated Slick mag. I ended up building him a new small 20 series Bendix and a wire harness to go along with it. I do a lot of mag work. The problem with most of these boats is either mags or carb trouble. And I am sure that our magneto work is much cheaper than a "certified" mag shop will be. About the plugs, is I like the different heat range plugs that Champion offers in the 18mm thread. Plus the Champion plugs are zinc plated so they will not rust as fast. The autolite plugs are black steel and seem to rust sooner which I hate to see on these custom motors
 
Hey DMB....

What's the reason for throwing away the autolite plug washers and installing copper aircraft plug washers?

Thanks

Doc
 
The only reason I suggest a certified shop is because you know they will build it right. From the example of work I've seen from Mike Thruman I have no problem recommending him for mag work even if it isn't a certified shop. On the forum I read where people had mag problems and they were going to fix the mag themselves by replacing a coil or some other part or have a guy who works on them do it. There is a lot more going on inside a magneto than the average mechanic can test for. A worn cam or bearing can be just bad enough that you can't tell until it is run at high rpm. For those tests you need a mag shop that has the equipment and experience to do the job right.

You are correct about the Autolite 386 rusting in a few weeks. I will try the Champions next. I don't care how pretty my engine is as long as it runs good. I never put an airboat in the water or a plane in the air without having the magnetos rebuilt. I learned my lesson in 1999 when I had to dead stick a homebuilt plane because I had bad magnetos. I was so mad at the mechanic which was also me. If I was a better mechanic I wouldn't have to be such a good pilot.

Bottom line is if you have a fuel or ignition problem on an aircraft engine, get the mag checked or rebuilt. If you still have problems, you know it is not the mag.

The reason for the copper washer is a better seal to the cylinder. Those thin plug washers are made for an insert that is tapered not flat. Pull a plug after you torque it and you will see the thin washer is distorted and not providing a good seal. Aircraft cylinders are flat, not tapered.
 
Thanks DMB......one more question.....what torque rating do you use on your plugs? I've never torque'd my plugs.......

Doc
 
I appreciate the advise.Does anybody know of a service manual I can buy on these engines?Something similar to a Chilton manual is what I was thinking of.
Speaking of the mags,what is the approximate price range for a rebuild?
 
You can send P2 a pm.
He can do mag work, and has this here machine for test runn'in it when he's done.
Cowboy_seal_of_approval.JPG
 
Classic Airboats sells one for about $95.00, don't quote me on price, its in there catalog on thier website.
 
This is out of Classics 2007 Catalog pg. 60.

OVERHAUL MANUAL FOR AIRCRAFT ENGINES
Don’t get caught short with the knowledge it takes to do a
complete and thorough engine overhaul. This is a must for all
professional and amateur mechanics.
60-64204 Lycoming Overhaul Manual......................88.00 ea.
60-64205 Continental Overhaul Manual................... 86.00 ea.
60-64206 GPU Continental Overhaul Manuel ............86.00 ea.
 
Ducarra aviation has the parts manual along with all the seals and gaskets and lot of other parts you may need. Classic airboats also have the manuals available, part number 60-64206.

esscoaircraft.com has the manuals for the 220 GPU too. Click on engine manuals, then Continental, then the PE-150. The parts manual is $27 and the overhaul manual is $30. I bought both manuals.

I don't use a torque wrench on my plugs either but the answer is 15 to 20 foot pounds. Always use anti-seize when you install the plugs and don't get any on the electrode.

Anyone who works on aircraft engines should have a bunch of those washers laying around. If not you can get just about anything at Aircraft Spruce.

The last mag I had rebuilt was almost $300 but it needed a lot of parts. I had him make me a new harness too but the one I got from Mike Thurman was way better and it cost less too. I usually spend less than $200 per mag, but the cost depends on the hours necessary to fix it and the parts required. Even if I had the outfit cowboy showed above I still wouldn't try to repair a mag because I don't have the experience. That experience is well worth the extra cost. Get a person who knows what they are doing and you can;t go wrong. P2 looks like he's on the right track for sure. Nice tester.
 
I've been waiting for a thread like this where I can give props to Mike Thurman :) As he said, I was tole to contact him for a set of plug wires for my GPU. After messing around with my old mag I eventually found it to really warrant a replacement, and Mike was awesome to deal with. Mike set me up with a Bendix Mag he reconditioned, and it works great! Also, he talked me through the timing process, and was beyond professional when it came to making sure I got exactly what I needed and that I was completely satisfied with my mag (and the entire process of buying it for that matter)

Thanks Mike for taking care of me :)


Jamie
 
How can I tell the difference between a Continental and a GPU?As you can tell,I don't know much about a air cooled engine.I can eat an automotive engine for breakfast,but a aircraft engine is a different critter.
 
Jamie, glad you are satisfied with the mag. Although you failed to bring up the part about we made the deal on Wednesday and you asked if you could have it by the weekend....in ARKANSAS! But to earn the business of a new customer I pulled off a overnight build and was waiting for the paint to dry so I could get it out on UPS for next day air delivery.. I guess after our talk on Saturday morning you got it installed and timed correct. I am happy to have made it happen. And I would like to thank Southern Airboat and it's board members because without you guys we would not have had the chance to do business with each other. And his check showed up Monday as promised
 
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