I was thinking about some of the same things lately. My last carb was in an 85 stang that I sold in 87. Not quite 20 years.
Here's a good article. timing It explains the process more clearly than I can.
I suggest you look for total timing of 34 to 36 degrees at 2500. The article suggests a little more advance than this but that's for a 302. The 331 will use a little less.
Stiffer springs, like stock, raise the rpm, softer springs lower it. The weights govern how much mechanical advance you get. Hope this helps you out. Remember, too little timing hurts power but too much causes detonation. HTH
Redfire Paint w/ silver Oct 07 306, 650 Holley 4150, Stealth, Performer Heads, B Cam, MAC Shorties, 3.73, Tremec.
You can index the distributer any way you like. I prefer to have #1 at about 10 o'clock. But it's strictly up to you; the engine doesn't care. As long as the rotor is pointing to the #1 post a little befor TDC, it's fine.
To set the pointer correctly you have to get the crankshaft exactly at TDC for the #1 cylinder, then adjust the pointer so it points at the TDC mark on the damper. I don't know a good way to get the crankshaft exactly at TDC after the heads are on, though I'm sure somebody does.
I suggest 12 degrees initial timing with a maximum advance of 34 degrees for the street. This may mean that you will have to back your initial timing down to 10 degrees to keep the limit of 34 degrees total.
Regards - Randy Racecar Fab/Support GT40 331 - Weber IDAs, G50 5spd 69 Camaro SS 4spd 2007 Toyota Camry Hybrid - 44.2 MPG daily driver 2002 Avalanche 2500 - Avian Target
My GT-40 Build Site: http://www.GT-FORTY.com
The MSD manual that came with your distributor has a good discussion on which of the springs to use, and which bushing (determines the amount of centrifugal advance that will occur). As a ballpark, set 12 degrees of initial timing at the crank, and use the blue bushing. The blue one allows 21 degrees of advance, which will give you a total of 33 degrees - a good, safe starting point. The springs will determine how quickly the 21 degrees at the distributor rolls in. A conservative starting point with the springs would be the two blue ones - they will allow full advancve at about 2,800 rpm according to the MSD instructions I am looking at.
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