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Magneto timing

jrussl

jrussl

BENEFACTOR
Madison, WI
I have a PA-18 with a freshly overhauled O-320 going back in and am having trouble with timing on the left mag. The engine mount has always limited the adjustment on the left mag as the mag hits the mount. The adjustment is limited to about 2/3rds of the normal adjustment.

I need 25 Degs before TDC. I can only get to about 17 degrees. If I reindex the mag one tooth over, I can only get 35+ degrees.

The right mag times perfectly.

Both mags overhauled less than 60 hours ago.

The internal timing on the left mag has been touched up and is exactly 10 degrees.

Bendix mags

New rubber motor mounts

One thought is that I can fudge the internal timing to make up for the lack of external adjustment but I know that will result in a weaker spark.

Does anyone have a suggestion on how to resolve this?

Thanks in advance

Jeff





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Success! Your suggestion worked perfectly, Kase. Just as you knew it would. Thanks again!


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Dan Gervae said:
Supercub.org always comes through.lol. Now go break I. That new overhaul.
Click to expand...

Getting pretty close to starting the break-in. Spent a few hours in the hangar again today and am running out of things to reconnect. Why does it always take so much longer than you expect? Time mags, install primer lines, route and secure starter cable, route and secure alternator wires, connect throttle, connect mixture control, connect carb heat, find new cable clamps for proceeding connections. Oh, did I mention that I installed a CGR-30p since the last time this engine was out? Route and secure new ignition wires. Fight with timing for way too long.

There are. just a lot of things to do. I know I am preaching to the choir as most of you can do this much faster in your sleep. Makes me appreciate all the skills and knowledge of many here even more. And also so many that are generous with their advice.

SuperCub.org is a great online community. One that I have been hanging around for some sixteen years now. Thanks to everyone that makes it so great.

Jeff


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jrussl said:
Getting pretty close to starting the break-in. Spent a few hours in the hangar again today and am running out of things to reconnect. Why does it always take so much longer than you expect? Time mags, install primer lines, route and secure starter cable, route and secure alternator wires, connect throttle, connect mixture control, connect carb heat, find new cable clamps for proceeding connections. Oh, did I mention that I installed a CGR-30p since the last time this engine was out? Route and secure new ignition wires. Fight with timing for way too long.

There are. just a lot of things to do. I know I am preaching to the choir as most of you can do this much faster in your sleep. Makes me appreciate all the skills and knowledge of many here even more. And also so many that are generous with their advice.

SuperCub.org is a great online community. One that I have been hanging around for some sixteen years now. Thanks to everyone that makes it so great.

Jeff


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Click to expand...

All sounds v.familiar from my firewall forward replacement last year!!!

Question, have you fitted a spin on oil filter? Or still with the “brick catcher” mesh filter?


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jrussl said:
I installed a Casper Labs right angle filter adaptor back in 2013. It works great and would recommend it.

Jeff


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Click to expand...

PERFECT!!! That’s exactly what I fitted last year and I’m delighted with it too!!!!

I was going to pass on Bill’s advice about using cheap auto filters for the first couple of break-in starts and for checking the contents, but I guess you already know it!!

I’m hoping to be doing my first oil change this week after the first 20 hours of running and I’m wondering whether the filter will come away easily, or become a fight!! What’s your experience of this?


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Philly5G said:
PERFECT!!! That’s exactly what I fitted last year and I’m delighted with it too!!!!

I was going to pass on Bill’s advice about using cheap auto filters for the first couple of break-in starts and for checking the contents, but I guess you already know it!!

I’m hoping to be doing my first oil change this week after the first 20 hours of running and I’m wondering whether the filter will come away easily, or become a fight!! What’s your experience of this?


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Click to expand...

I generally use Tempest filters and a 1” socket to get them on/off. Never had an issue with removing them.

Jeff


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jrussl said:
I generally use Tempest filters and a 1” socket to get them on/off. Never had an issue with removing them.

Jeff


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Click to expand...

GREAT to hear!! I’ve heard horror stories of trying to get filters off!!

I’ve got the Champion one it came with on at the moment and ordered a couple more of those. Are Tempest better? I could easily change to those :)

1” socket all ready to go :)


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Philly5G said:
GREAT to hear!! I’ve heard horror stories of trying to get filters off!!

I’ve got the Champion one it came with on at the moment and ordered a couple more of those. Are Tempest better? I could easily change to those :)

1” socket all ready to go :)


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Click to expand...

Tempest are a little less expensive and, in my view, similar quality.

Jeff


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jrussl said:
Tempest are a little less expensive and, in my view, similar quality.

Jeff


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Click to expand...

Ok, I’ll try them next, thanks Jeff!

By the way, I noticed in another thread you were asking about the trim pulley. I’ve asked and answered quite a few questions about this and have replaced my front pulley and done the Oilite bearing mod, which I fully recommend, let me know if I can help you on this :)


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I had this same issue on the my Super Cub with Continental sL4N mags. Could only get to 19 or 32 btdc. with the engine mount interference and also the limited travel in the slot that you can rotate the magnetos in. Quick google search brought me right to this thread. Wasn’t exactly a five minute fix… more like an hour of fussing with getting cotter pin out, rotating gear 180, re-torquing nut, cotter pin back in correctly, and timing all while working in a tight space between the engine and firewall. Anyhow it did fix the problem, so thanks! Wish I would have read this post before I installed the engine on the airplane…
 
Mate, in aeroplane engineering timescales, just an hour to fix a fundamental problem is basically a get out of jail free card ;) Well done everyone for facilitating this!!!
 
pwinfrey said:
Wish I would have read this post before I installed the engine on the airplane…
Click to expand...
But you wouldn't have known till it was installed and you tried to time it. There is always that monkey wrench thrown in. If it was easy, everyone would do it. ;)
 
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