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My Question Is About Total Timing Of My Small Block Chevy . I Set My Base Timing At 8 Degrees With My Vacuum Advance Disconnected And Line Plugged. Vacuum Is Connected To Ported On Holley Carb. When I Connect Vacuum Line And Raise Rpm To 2500 , I Then Check With Timing Light And Turn Knob On Back Of Light To Bring Mark On Balancer Back To 0, My Total Timing Amount Is 53 Degrees. I Thought I'm Not Supposed To Exceed 32. Is Total Timing Base + Mechanical +vacuum Or What?????
 

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Total is base plus mechanical, diconnect and plug the vac advance and retest total.
 

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NATRAD said:
My Question Is About Total Timing Of My Small Block Chevy . I Set My Base Timing At 8 Degrees With My Vacuum Advance Disconnected And Line Plugged. Vacuum Is Connected To Ported On Holley Carb. When I Connect Vacuum Line And Raise Rpm To 2500 , I Then Check With Timing Light And Turn Knob On Back Of Light To Bring Mark On Balancer Back To 0, My Total Timing Amount Is 53 Degrees. I Thought I'm Not Supposed To Exceed 32. Is Total Timing Base + Mechanical +vacuum Or What?????
Total MECHANICAL Timing is base + the built in mechanical timing of the distributor.

Total Timing is base + mechanical + vacuum.

However; when referring to the maximum timing of your engine only the Total Mechanical Timing is considered as there is no vacuum advance (or very little) at WOT under load. This is true whether you are connected to ported or manifold source.

Your timing should be checked and adjusted with the vacuum advance hose disconnected from the vacuum cannister and plugged! Re-connect after setting/checking the timing and then adjust the idle if it has changed from your optimum setting.

The 53 degrees you are seeing the way you are checking is normal and not a problem.
 

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I'm not going to argue this or play semantics. Your total timing is base plus mechanical. When you add vacuum into the equation total advance will vary with RPM and load.

Therefore when checking total timing at a set RPM it's with the vac advance disconnected. Verifying the timing without the vac advance hooked up should bring the total into the 30's range.
 
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