| Author | Message | ||
     micky dee (Kincangokicker) Member Username: Kincangokicker Post Number: 51 Registered: 06-2003 |
how do you check if vacum advance is working properly. the old 3.9 seems sluggish also would advancing timming be benifictial and if so how much to advance. | ||
| Tony Zuniga (Tony23007) Member Username: Tony23007 Post Number: 169 Registered: 05-2003 |
I would not recomend advance timing, it leads to engine pinging and possible Piston failure. | ||
| David Beard (Daveb_in_rsa) New Member Username: Daveb_in_rsa Post Number: 5 Registered: 07-2003 |
First you need to set the timing at idle (with the vacuum advance pipe disconnected). Then rev the engine and the advance weights should cause the timing to advance (check it with the same timing light). Then reconnect the vacuum advance pipe and rev again - the advance should be more as it is a combination of mechanical and vacuum. You can also check the vacuum advance unit by disconnecting the pipe from the manifold (still connected to the distributor) and sucking on it. If there is no resistance, the diaphragm has split and needs to be replaced. Stick with the timing recommended in your handbook for your particular model to avoid pre-ignition damage to the pistons. | ||
| Shaun Power (Shaunp) Member Username: Shaunp Post Number: 145 Registered: 05-2003 |
Micky if you want to test the advance diapram just suck on it and see if it holds vacuum. I find they are always stuffed. Also check that the mechanical advance is just stuck. Static ignition advance is generally specified by the factory to meet local requirement ie emissions and fuel octane. I find most are happy around 6-8 deg BTdc, on 91-92 octane, if it pings retard it. |
