Engine starting issue

[robbie]

When starting the A65 the prop backs up has 2 bendix mags one has and impulse coupling starts on that mag. Mag was removed checked over and new coil installed my AP reinstalled and set it to 28* to help to start easily for an old man
I notice while pulling it thru slowly the impulse coupling click
At 28* is this right I was thinking it should be closer to TDS
Any through on this

[3Dreaming]

Re: Engine starting issue

The impulse should release close to TDC. If the impulse is truly tripping at 28 degrees before TDC, then the mag is actually firing around 60 degrees before TDC.That is not good.

[Scott]

Re: Engine starting issue

Are you selecting both mags on or just the one with the impulse coupling?

[robbie]

Re: Engine starting issue

Scott no on impulse mag

[robbie]

Re: Engine starting issue

3 dreaming mag is set to fire at 28* with timing box
Thinking the problem is a retired AP and I rewound the spring in the impulse Coulter. Reading it should of been wound 1 to 2 turns. We wound it much more than that. Supposedly the spring winds up and give you the 20*delay in firing

[robbie]

Re: Engine starting issue

3 dreaming mag is set to fire at 28* with timing box
Thinking the problem is a retired AP and I rewound the spring in the impulse Coulter. Reading it should of been wound 1 to 2 turns. We wound it much more than that. Supposedly the spring winds up and give you the 20*delay in firing

[3Dreaming]

Re: Engine starting issue

I suppose if you had the spring wound to tight it might cause the impulse to trip, but normally the spring only provides the spinning force. The triggering of the impulse is mechanical through the dogs and pawls.

[3Dreaming]

Re: Engine starting issue

Also the starting issue might not even be from the mags. If the fuel mixture isn't correct it will kick back. A throttle that is not closing all the way, a plugged passage in the carb, or an intake leak could cause similar problems.

[Edwin Otha]

Re: Engine starting issue

If the prop is backing up when trying to start, it's too lean. Prime it some more. If it doesn't do anything, and everyone that has propped has their tongue hanging out, it's too rich and needs to be cleared out.
EO

[Scott]

Re: Engine starting issue

Make sure the mags are wired correctly to the switch ie you are in fact grounding the none impulse mag.

[robbie]

Re: Engine starting issue

When pulling the prop thru slowly when the mag trips at 28* That the point where the mag is timed too

When the dogs hit the stop shouldn’t the spring continue to wine tight then force the dog off of the post
I’m looking for the mag too release at about 10* BTDC. The impulse I was told is suppose to delay the firing about 20*
Thank you everyone comments keep them coming
Did not this problem till mag was removed this spring for new coil

[robbie]

Re: Engine starting issue

Scott thank check to p leads for going to the correct points on the switch

[mike lutz]

Re: Engine starting issue

with mag off engine rotate till impulse snaps (trips) on number one. Back it up slightly and you will feel the e-gap. Don't back it up so much as to engage the pawls. Install the mag back on engine setting at 30 degrees (a-65). Put mag synchronizer on the p-lead and adjust mag till the light just goes out, then tighten mag. Should work for you. As mentioned in above post, make sure the correct p-lead is verified on the correct mag. You want the points to open at 30 degrees, not the impulse. The impulse will delay the firing of the mag on start up, and after rpm comes up the counter weights go out and the mag will fire at 30 BTC.

[robbie]

Re: Engine starting issue

Mike. Isn’t it the impulse that delay the point from opening at 30* when propping. Under stand when running the dog is out of the picture

[robbie]

Re: Engine starting issue

Mike. Isn’t it the impulse that delay the point from opening at 30* when propping. Under stand when running the dog is out of the picture