ported timing
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
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From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
I re-read his posts. I think he's saying that if you don't have a means to retard mech'l advance at idle when you increase initial to achieve a stable idle (with vacuum connected), then you are only left with increasing vacuum advance at idle to get a stable idle.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Yes, the people that insist on using full vacuum to the dizzy are adding timing degrees at idle
It is easy to see. Setup an initial timing with vacuum advance blocked off. Then plug in the full vacuum port and watch the timing jump up
It is easy to see. Setup an initial timing with vacuum advance blocked off. Then plug in the full vacuum port and watch the timing jump up
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
I have a stock SB engine, distributor re-curved per Lars recommendations. At normal idle speed, that gives me about 12-13* advance with the vacuum can blocked off. Add in the vacuum can and it idles very smoothly and performance is considerably enhanced from GM's 'recommended' base timing method.
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
Thanks, but I'm not getting it.
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
100%. That's why I insist on running manifold vacuum.
