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Ported or Manifold Distributor Vacuum?

Old Today, 11:51 AM
  #21  
Hamerdown
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Originally Posted by lars View Post
You need to increase your mechanical timing - 32 degree total is not enough. Bump your timing up at least 4 degrees so you get 36 total and 16 degrees initial. Your vacuum advance is too long - your numbers show that you have a 23 degree long vacuum advance can. You need to replace it or limit it to 12 degrees.
Lars
I originally set it for 35-degrees at 3000 rpm.
But when I hooked up the vacuum and read the much higher numbers I bumped it down in attempts to lower it some...didn't really help.
Looking at the info you sent me to find a GM HEI 'can' with 12-degrees in it (I'll even take 10 degrees) then hoping my local parts store can get it.
thanks

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Old Today, 01:36 PM
  #22  
Bikespace
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The GM HEI can is probably your best bet. I used an Accel 31035 adjustable vacuum advance, which according to the installation notes, can be adjusted to limit max advance from about 3 to 21 degrees.

Accel 31035
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Old Today, 02:18 PM
  #23  
Its_hers
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While you've received a wide range of opinions, my suggestion is to do this properly. Take the distributor out and send it to a professional who will will tailor the curve and limits so you know what your initial should be without guessing.
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Old Today, 03:55 PM
  #24  
resdoggie
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Originally Posted by Hamerdown View Post
I originally set it for 35-degrees at 3000 rpm.
But when I hooked up the vacuum and read the much higher numbers I bumped it down in attempts to lower it some...didn't really help.
Looking at the info you sent me to find a GM HEI 'can' with 12-degrees in it (I'll even take 10 degrees) then hoping my local parts store can get it.
thanks
It doesn't matter what your timing is at idle as long as the car starts and runs smooth. As soon as you reconnect the vacuum advance canister the timing at idle will increase to whatever the max advance is for the canister e.g. 15 degrees. So yes, for example, you may have 16 initial, 5 mech'l advance at 800 rpm and 15 degrees vacuum advance for a total of 36* AT IDLE only. As soon as you step on the gas, initial remains the same, mech'l increases with rpm's and vacuum advance drops relative to the drop in vacuum because the throttle blades are open more. Follow what Lars is suggesting. The Accel canister mentioned above may be what you need for adjustability.
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