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DUI Timing adjustment help..... and MSD parts interchangeable?

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Old 05-20-2016, 11:15 PM
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I have no idea what ideal timing would be but my DUI is giving me 18* at idle and 36* max on my 502.
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Old 05-20-2016, 11:40 PM
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34 to 36 total for an engine like yours. Big cams allow more initial timing for a quick,cleaner start.You want the motor to have as much initial timing as possible without kicking back or dragging down the starter and at the same time still have plenty of initial timing to get quick,easy starts.This will also help with a nasty,rich idle and will give you a better response to carb adjustments. The amount of advance in an MSD is adjustable by changing the bushing you mentioned earlier. The black MSD bushing gives 18* of advance. When set at 36 total you would have 18 initial. Not sure what DUI does to control the amount of advance in their distributors. Question, does your engine idle strong and clean or weak and rich?

Last edited by picklenjim; 05-21-2016 at 01:41 AM.
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Old 05-21-2016, 09:08 AM
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Originally Posted by picklenjim
34 to 36 total for an engine like yours. Big cams allow more initial timing for a quick,cleaner start.You want the motor to have as much initial timing as possible without kicking back or dragging down the starter and at the same time still have plenty of initial timing to get quick,easy starts.This will also help with a nasty,rich idle and will give you a better response to carb adjustments. The amount of advance in an MSD is adjustable by changing the bushing you mentioned earlier. The black MSD bushing gives 18* of advance. When set at 36 total you would have 18 initial. Not sure what DUI does to control the amount of advance in their distributors. Question, does your engine idle strong and clean or weak and rich?
I guess from what im reading you have no choice but to send the distributor back to DUI... It seems as if the engine idles OK, but if anything Id say a little rich. Never stalls in or out of gear....


Originally Posted by Baja Rooster
I have no idea what ideal timing would be but my DUI is giving me 18* at idle and 36* max on my 502.
Thats about the timing that one of the guys was telling me... Did you have DUI set the distributor to 18* advance when you bought it or were you able to adjust yourself?? Mine has 24* advance built in...

Thanks, Chris
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Old 05-21-2016, 09:28 AM
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Originally Posted by Black Baja
Do yourself a favor and buy a decent carb. Speed Demon=junk. Nickerson modified carb = bigger piece of junk. Buy a new Holley or a Quick Fuel and go boating. After you recover from the sore rectum you recieved from dealing with Nickerson get a decent ignition.
I've had a 850 Sea Demon and 650 Sea Demon. Both where great.
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Old 05-21-2016, 12:53 PM
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Originally Posted by cdaniel525
I guess from what im reading you have no choice but to send the distributor back to DUI... It seems as if the engine idles OK, but if anything Id say a little rich. Never stalls in or out of gear....


Thats about the timing that one of the guys was telling me... Did you have DUI set the distributor to 18* advance when you bought it or were you able to adjust yourself?? Mine has 24* advance built in...

Thanks, Chris

I had a friend of a friend of a friend's dad who owns a carb/ignition shop and I gave it to him to check out. I had no idea what he did until I just checked my timing last night. I don't know how it came from the factory but it seems to work well with my motor.

On a side note - when starting her up after the winter the tach doesn't work. It's entirely possible that I hooked the power wire to the tach lead at one point but can't be sure and it's possible the 20 year old guage gave up the ghost. I tried checking the tach lead while running with a test light but it just glowed steadily. I checked the interwebs on how to check the distributor signal but to no avail. Any tips? Sorry for the thread jack.
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Old 05-21-2016, 07:55 PM
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DUI has no user adjustments, but they have always helped everyone I've seen writing about it. They individually curve each diz for your needs.
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Old 05-21-2016, 08:08 PM
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To check the tach check the tach terminals for running voltage at the power stud, ground at the GND stud. And if you don't trust the gray wire run a temporary jumper from the coil negative to the signal stud on the tach. If it doesn't work Mercruiser says dump it. They don't give a test.
Tachometers can fail, my 88 took a dump in 2010, made my engine stumble too. POS, only lasted 22 years in a wet outdoor environment!
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