National Aeronca Association Bulletin Board

As long as we're researching problems, I have a question that's been bugging me for a while. My 65 came with new Slick mags and ever since I've installed the engine (some 100 hours ago) the mags "clacky, clacky clacky" after I start it and until I advance the throttle. Obviously, it's the impluses (duel mags) making the racket so the simple solution would be to set the idle faster, but if I set it to the point where the mags settle down right after starting, the idle is way too fast for my liking (probably around 850 rpm). Right now, I'd say it's set at about 700 rpm already. Never had this problem with the old Eiseman mags.

Ever heard of this.............and any ideas??

Mike

Recheck you mag timing and installaton if you are hearing the impluse after starting.. Make sure the Slick mag is locked with the pin when installing.

Mike,
I,d pull them off for a look. The impulse flyweight should be out of the way by 700 RPM.
Paul

Mike: Seems like the weights are too light . Could be sticking or tight. I remember when I bought the new impulse coupling for my Bendix it had springs on the dogs to make them engage more postively. Thought that it would need a higher rpm to disengage. To my surprise they are out of the picture around 300 rpm. If both mags are doing the same thing, check the workings of the impulse components . Maybe Slick would have the solution. I agree that 7-800 would be dicey on a hand prop engine. It won't stay stay in one place and the door wants to close on you from prop blast.
Ron

Guess the best solution would be to contact Slick as Nathan suggested. These are (or were) brand new mags and have done it from the first installation. Timing is exactly on the nose at 30 degrees, but I doubt that would have bearing on the problem. Once the throttle is advanced slightly it runs just fine.

Does anyone know the address for Unisom or Slick magnetos? I've been "googling" for it with no luck. I used to have a direct email address at one time, but must have lost it.
Thanks......Mike.

Suppose all you lucky stiffs are headed for Middletown........hope to see some of you at Oshkosh, anyway.

Mike

World Headquarters
Unison Industries
7575 Baymeadows Way
Jacksonville, FL 32256

Phone: (904) 739-4000


You'll get a cute sounding girl that can direct your call.

nkh

Well, had a email from the guy at Slick and he contends that the impulse nut is probably overtorqued causing the impulse to bind at startup. According to specs, the nut should be torqued to 120-320 inch pounds which I'm quite sure it was at installation, but it does make sense. Anyway, his suggestion is to make an inspection of the impulse and then retorque to a lower torque setting (200 inch pounds or less) and see if there is an improvement.

120-320 inch pounds is a pretty broad torque range, especially if there's a chance the impulse could get bound, but expect we'll have to pull the mags and check. Let you all know how we make out.

Mike

I overhauled an A-65 last year with New Slick Mags. I had to call the
factory rep due to the fact I could not install the cotter key within the
torque spects given. They said they were having the same problem.
They sent me two more nuts to try, and I was able to install them ok.
The way the new nuts are made, makes it easy to over/under torque
to be able to install the keys. If anyone else has this problem, just
call and they will be very helpful. Love that dual impulse.

I have slick mags on my 85 champ. they are pretty new, 3 years old ...maybe. They make no noise on start up. Also....when I had a 140 cessna, it had the owners manual on the 85 cont. It stated that oil did not flow correctly below 700 rpm and to try not and idle it below this rpm for any length of time. Do I remember this correctly? I'd like to know this for sure. Anybody?

I've found that if I 'bump' my throttle up slightly, the problem goes away. There is a spot where it will just barely increase the speed to the point where the impluse stops clicking. I chock it anyway. I'm still going to pull the mags though and check the torque. Just have to get together with my AI for legality purposes. On the other hand, who knows how accurate the 50 year old tach is? I know one thing, mine is quite a bit faster than the old yellow club plane. He pretty much had to run 2250 to keep up with me when I was running 2150. Same engine/ same prop. Need to get the tach checked, too.

JC regarding engine idle speed: not one to argue with a operator's manual, but doubt 700 rpm will harm the engine as it should be making plenty of flow. My L16 operator's manual (C85) says idle speed 700-800 rpm. Lasher suggests 600 rpm, at least on a 65. Your guess is as good as mine. I think the correct idle would be where the engine idles smoothly as possible and still doesn't strain at the chocks. I never worry about it on grass......blacktop different story. Also, if the idle speed is set too high, it increases the landing distance (or so it seems) although the prop is 'windmilling'.

I think our yellow dog (club plane) idle speed is set about 650 according to the tach and it's smooth running (new $8500 overhaul).

Mike: For what it's worth, my cold idle is around 550-600 and hot idle is around 750 rpm. Not a fan of real low rpms for warm up so I generally run it at 1000-1100 after about half a minute. I'll run it at that speed while fastening the seat belt, and doing the normal ramp checks. This will ensure good rocker arm lubrication, and cylinder lube, where it may not be as good at the full idle position.
Ron