480 mag timing

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444kyle
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480 mag timing

Postby 444kyle » Wed Dec 09, 2015 2:17 pm

I have set the motor to TDC by the timing mark under the 5/8 plug on the left side of motor. I then marked my ring gear and then counted the teeth on the ring gear. which was 123. I then did the math and it came out that 25 degrees before TDC was 8.5 teeth so marked that on the ring gear.

So my question is does the points open at the 25 degrees mark? Cause my mags were running ok but wanted to check them out now i reinstalled then to the same position as before. and when i check it the points are opening at like 5 degrees before not 25 degrees.
I think i understand the way its supposed to be setup. but this has me confused.
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GMAC 76
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Re: 480 mag timing

Postby GMAC 76 » Wed Dec 09, 2015 6:22 pm

yes the points should just start to open at 25 degrees......make sure when you set the engine for timing you do so in the direction of rotation so as to eliminate all gear lash.....I thought the timing pointer for the gso was in the top of the gear box...if the gear box has been removed you can time off the flywheel because it is mounted to the crankshaft...but if the gear box is still on the engine then you have to factor in the gearbox ratio from the crank to the prop flange ....that's why the timing pointer is in the gearbox

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Re: 480 mag timing

Postby TIGO541 » Wed Dec 09, 2015 8:47 pm

PM sent
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Bruce
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Re: 480 mag timing

Postby Bruce » Wed Dec 09, 2015 8:48 pm

GMAC 76 wrote:yes the points should just start to open at 25 degrees......make sure when you set the engine for timing you do so in the direction of rotation so as to eliminate all gear lash.....I thought the timing pointer for the gso was in the top of the gear box...if the gear box has been removed you can time off the flywheel because it is mounted to the crankshaft...but if the gear box is still on the engine then you have to factor in the gearbox ratio from the crank to the prop flange ....that's why the timing pointer is in the gearbox


theres a pointer in the acc housing on a 480 rudderstick side
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Re: 480 mag timing

Postby GMAC 76 » Wed Dec 09, 2015 9:43 pm

Bruce wrote:
GMAC 76 wrote:yes the points should just start to open at 25 degrees......make sure when you set the engine for timing you do so in the direction of rotation so as to eliminate all gear lash.....I thought the timing pointer for the gso was in the top of the gear box...if the gear box has been removed you can time off the flywheel because it is mounted to the crankshaft...but if the gear box is still on the engine then you have to factor in the gearbox ratio from the crank to the prop flange ....that's why the timing pointer is in the gearbox


theres a pointer in the acc housing on a 480 rudderstick side

good info....did not know that about the GSO 480....learn something new everyday!!.....so that pointer is in addition to the one in the gear box

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444kyle
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Re: 480 mag timing

Postby 444kyle » Thu Dec 10, 2015 9:24 am

how advanced past 25 degrees can you go. mine was set to open at about 6-8 degrees past the 25 pointer.
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Re: 480 mag timing

Postby farmboy » Thu Dec 10, 2015 6:32 pm

444kyle wrote:how advanced past 25 degrees can you go. mine was set to open at about 6-8 degrees past the 25 pointer.

I've never got a answer for that question from anybody. I will say my motor was a pig at 25 degrees. We bumped it up to 27 and it brought it to life and help smooth it up. I don't think I'd go any past that tho.
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Re: 480 mag timing

Postby farmboy » Thu Dec 10, 2015 6:33 pm

Tigo541 could answer that question for you better than I could tho...
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Re: 480 mag timing

Postby TIGO541 » Thu Dec 10, 2015 8:01 pm

GMAC 76 wrote:
Bruce wrote:
GMAC 76 wrote:yes the points should just start to open at 25 degrees......make sure when you set the engine for timing you do so in the direction of rotation so as to eliminate all gear lash.....I thought the timing pointer for the gso was in the top of the gear box...if the gear box has been removed you can time off the flywheel because it is mounted to the crankshaft...but if the gear box is still on the engine then you have to factor in the gearbox ratio from the crank to the prop flange ....that's why the timing pointer is in the gearbox


theres a pointer in the acc housing on a 480 rudderstick side

good info....did not know that about the GSO 480....learn something new everyday!!.....so that pointer is in addition to the one in the gear box

Yes sir but the gear box is precise timing. Accessory just gets you in the ball park in my experience
13-6x7-6 Hamant Ultra-lite,Custom TIG Stainless rigging,1.7 Rotator,Supercharged 480,Electronic Ignition,80 inch 3BLD R,B&S trailer

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Re: 480 mag timing

Postby TIGO541 » Thu Dec 10, 2015 8:04 pm

farmboy wrote:Tigo541 could answer that question for you better than I could tho...

Keep it at 25 otherwise there are too many factors that may damage engine if not careful and you have to know just what to do to get more advance in it correctly
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Re: 480 mag timing

Postby farmboy » Fri Dec 11, 2015 6:52 am

TIGO541 wrote:
farmboy wrote:Tigo541 could answer that question for you better than I could tho...

Keep it at 25 otherwise there are too many factors that may damage engine if not careful and you have to know just what to do to get more advance in it correctly

I will agree with you on that. Better to be safe than sorry...
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444kyle
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Re: 480 mag timing

Postby 444kyle » Sat Dec 12, 2015 9:19 am

ok still wont run. ok boat was set to 25 degrees by the pointer on the side. mags were removed and the red gear was set to the center of the window on the mag then reinstalled. both done the same way. and i have good spark at the points and at the plug but it still wont fire on the left mag. So in it has spark and im im 95% sure its not timed wrong since the other mag was set the same way and it runs fine. I would have to say it would have to be the plug wires in the wrong location making the ting off to plug location.
This is what i used to wire the plug wires. the wire are the same as listed on the chart. the only thing that is different is the picture shows #1 at the top of the pic but when it is installed #4 is at the top because the mag is rotated a quarter turn for install.
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14ft JB Hull,Lycoming GSO480,10 blade warp drive


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