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Discussion Starter · #1 ·
Just got the timing light back out since the new HEI and noticed it’s only got 16 degrees of mechanical advance. That seems really low to me. That means I’d have to set my initial timing at around 18 degrees. And with 20 degrees of vacuum advance, I don’t think the car would start with that much advance.
Should I just turn the vacuum advance way down and just roll with it? It does seem to like scary amounts of advance.
 

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I don't know how that works for you, but on mine, I have it set for 17* advance and it runs great, and no problems.
 

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Discussion Starter · #3 ·
I don't know how that works for you, but on mine, I have it set for 17* advance and it runs great, and no problems.
Is 20 degrees of vacuum with 18* initial going to be too lean at idle? Or is that pretty normal?
 

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18 degrees initial timing sounds pretty high. What is your total advance timing?
 

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I don't know about your setup, I have the idle set at 700 rpm. I have a Comp Magnum cam, and this how mine is setup. I use manifold vacuum instead of getting the vacuum from the distributor.
 

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Do you know which HEI you have?
As you know already, the weight of the weights and the springs control how fast or slow the centrifugal advance comes in.
The weights normally move down a track.
Some of them can be altered to allow the weights to travel a little further out, providing a slightly higher centrifugal advance. Basically lengthen the track.
You can also put a small weld just inward of their travel, to reduce how much it brings in.
 

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1960 454ci th400 61cad int. & pwr options
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18 initial plus 16 mechanical would be 34 degrees total.
Not sure if I missed this or not but is 34 degrees what you are reading with the timing light at full advance (as opposed to calculated)? If so is it running/starting well or are there some issues causing concern for the settings? In general if it starts and runs without pinging under load those settings will be fine.
 

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Discussion Starter · #9 ·
Not sure if I missed this or not but is 34 degrees what you are reading with the timing light at full advance (as opposed to calculated)? If so is it running/starting well or are there some issues causing concern for the settings? In general if it starts and runs without pinging under load those settings will be fine.
Yeah, it’s reading 34 with a timing light. Seems like a lot of initial timing but it does seem to run good that way. Except when I connect the vacuum line. Then it won’t start. I’m guessing I should just turn the vacuum can down from 20 degrees to 10 or less?
 

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Discussion Starter · #10 ·
So it looks like I found my sweet spot.

16 degrees initial timing
32 degrees total
7 degrees vacuum advance

I mixed that with smaller metering rods and 7” step up springs.
Man did those tires spin all way down the block.
I have to lightly tap the gas pedal before flooring it, so maybe I’ll try 1 size up on the secondary jets.
Seems like a lot of initial timing to me, but it seems to like it. Every car is different. Glad I switched to Edelbrock. That demon carb is way too much hassle to figure out when you’re lacking experience.
 
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