Team Chevelle banner

Timming - I'm lost

1633 Views 9 Replies 6 Participants Last post by  onovakind67
Ok guys i have been reading some old posts - trying to figure out how to correctly set my timming - and all i am getting is confused. I will try to post what i've gathered from it and maybe somebody can shed some light on this and correct my wrong ideas. 1st) You need to disconect the hose going from the vacuum advance pod on the dist.to the carb and block them off. 2nd) I have heard two different theorys on how to set the initial advance - one is off the timming tab and # two is to rotate the distributer. (which is it - or is it both) - like you use the tab to get it where you want it and then rotate the dist. to readjust -maybe to make it start easier and then rotate it again to bring it back to where you want it? 3rd) I know the mechanical advance is all in the weights and how fast it comes in is due to the springs but where does the vacuum advance come into play? It's got to be there for a reason. 4th) Total timing as stated by a tech archive is the initial plus the mechanical - i can understand that ( minus the fact that i still dont know where the vacuum advance comes in) but then it says that to adjust total timming (holding the engine at 3000 rpms to 3500 rpms - depending on when all the timing is in) to rotate the distibuter - this doesnt sound right to me and maybe i am misunderstanding it but wouldnt that make the initial timming lower or higher ? I want the initail to stay the same and the "total" to be correct and to do this i would have to change the weights right? Maybe i have answered my own question here but what i think it is that i need to know is how to check the timming - to make sure it is right. I know i will need to get a balancer tape and a timming light but how do i go about it. - Once i have my intial set where i want it do i - just play with the weights until they are where i want them or do i just rotate the dist.? Thanks for letting me aimlessly ramble and for any replies that come from it.

Dan
See less See more
Status
Not open for further replies.
1 - 1 of 10 Posts
For an explanation of vacuum advance, think of the vacuum advance as a "load sensor" for the ignition system. As the load on the engine increases, the amount of timing that it requires is decreased. At light loads the engine can tolerate more spark advance, so the vacuum advance is added to the initial + whatever mechanical advance you have. The vacuum advance system is what allows you to run this extra spark advance at light loads. As the load increases, the vacuum advance provides less and less advance. So, you can think of the vacuum advance as a "vacuum un-advance" in that it un-advances the timing as the load increases.


Hope this helps.

MIke
1 - 1 of 10 Posts
Status
Not open for further replies.
Top