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Discussion Starter #1 (Edited)
setting my timing..vac ad plugged..shows around 12 deg advance at idle..set light at 36 for total advance rev motor till 3000 or so mark is way off..dial back the light till 14 or 16 degrees before timing marks line up..am i over looking something here..i'm sure the answer is obvious but i don't get it...help please thanks cranker
 

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Your advance is not working.

AL
 

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I think your advance is working, just you only have 12 or 14 degrees. Add the 12 degrees initial = 24 or 26 degrees total. You either need to increase your advance curve 10 degrees or set your initial to 22-24. The proper choice will depend on your engine combination.
 

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Discussion Starter #5
engine combo..stock bore 350,vortec heads,rpm performer,comp 274 490 lift 230 [email protected] .050 can you set initial timing that high?? wouldn't that make it very hard to start? sorry for the ignorance
 

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If you set 12 degrees at idle (initial timing) and @ 3000 RPM you only have a couple more degrees then your mechanical advance mechanism is sticking!! Remove the cap and rotor and make sure the weights move freely. You might need a "Curve kit" that comes with all of the weights and bushings to rebuild and tailor it to your needs.
Is it an HEI??
 

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Discussion Starter #9
just checked the weights and springs all look and seem to work fine..i am doing this the right way??? set light to 0 check initial timing.. then set light to desired total advance 36 and check it or do i set it to initial plus whatever makes the difference...say 14 innitial then set the light to 24 that equals 36
 

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just checked the weights and springs all look and seem to work fine..i am doing this the right way??? set light to 0 check initial timing.. then set light to desired total advance 36 and check it or do i set it to initial plus whatever makes the difference...say 14 innitial then set the light to 24 that equals 36
Nope....You're doing it right. You might also need to consider that the stock weights and springs aren't gonna let the advance come in that early. Look at the links in my earlier post.:yes:
 

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Set it to zero and check initial.
That is 12 degrees by your statement.

Rev it to 3000. Turn back the dial until it reads zero mark.
Read what dial setting is.
If it says 26 degrees that's your total.

26 total minus 12 initial = 14 degrees of mechanical advance


If your HEI is stock then your advance is not working properly or has been modified.

A stock HEI might be set up for 8 degrees of initial and 30 degrees of mechanical for a total of 38 degrees.
 

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Discussion Starter #12
sounds good i'll go get this stuff right now..do you just start with the lightest spring and work up from there or the other way around...thanks for the info
 

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sounds good i'll go get this stuff right now..do you just start with the lightest spring and work up from there or the other way around...thanks for the info
The "Safest" way is to start with the heavier springs and work your way down until you hear some pinging and then just swap ONE of the springs back to the next heavier. Your goal is to find the MOST advance the engine will tolerate at any given speed/load. That's where the best performance and efficiency (MPG) will be found.:yes: On SOME of the advance kits the lightest springs are TOO light and will let the advance mechanism "Bounce around" in the higher RPM ranges. NOT good for sensitive engines..:no: ESPECIALLY is any nitrous is being used!!!:eek:
 

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The springs have no effect on how much sweep you have. That's a mechanical limit, usually the slots in the wieght plater detrmine that. The springs control the slope or rate at which maximun advance is reached.

Having actually tuned distributors myself other than using a welder :rolleyes: typically I've found that most performance motors with a decent cam respond well to one lightest and one medium spring. That gives you a curve starting at around 1000 RPM and finishing around 3000 RPM. With Vortec heads you may want to stick with that, any faster and you might encounter some pinging during low speed tooling around below 3000 RPM.

There's a hundred other factors involved in finding what initial is best, how much total your motor can use. Too much to describe here.
 

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This is "roughly" what the spring weight kit does from Mr. Gasket. If you look at the chart you can see the lightest or black springs are too fast of a curve and the silver ones are just a bit too slow. Using a combination of one black one silver seems to work well on most motors. Those that don't live in a black hole.

 

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This is "roughly" what the spring weight kit does from Mr. Gasket. If you look at the chart you can see the lightest or black springs are too fast of a curve and the silver ones are just a bit too slow. Using a combination of one black one silver seems to work well on most motors. Those that don't live in a black hole.
MSD has a good chart in their mechanical advance tuning kit instrux that gives curves of all/most of the spring combos:

http://www.msdignition.com/instructions/Products/Distributors/8464.pdf
 
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