1979-1993 & 94 Conv [Subscribe to Daily Digest] |
![]() | [Main C900 Bulletin Board | BBFAQ |
Prev by Date | Next by Date | Post Followup ]
Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Re: Vacuum Advance question Posted by Ari [Email] ![]() ![]() In Reply to: Vacuum Advance question, Jeff Cunningham, Wed, 14 Feb 2001 13:03:00 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Actually, I think it's vacuum retard. The timing is retarded at idle (high vacuum), and as the engine accelerates, the vacuum level decreases and the timing is allowed to advance. Advancing the timing at higher RPM is necessary because some things (like how fast the flame front moves) doesn't speed up as much as the piston speed. So you need to set off the spark sooner so that the fuel burns at the right time when the piston gets there. At idle, the piston speed is slower, so you 'delay' the spark so it doesn't start the fuel burning before the piston gets to the top.
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
![]() |
![]() |
![]() |
![]() |
![]() |