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Setting the timing.
#1
So I disconnect the vacujm advance, and time it. Without the vacum my total timing comes in at 36 degrees at 3000rpm. When I connect the vacum back up it adds about 12 degrees is this too much? Am I doing this right?
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#2
On what car? Your 1fastvette? What year, what engine, etc?
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#3
its a chevy 383 stroker. In my Vette.
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#4
Are you using ported or full vacuum?
2001 yeller Cobra, Ford GT fuel pumps, 80lb injectors, Bassani X-pipe, Borla Stingers, 323 Big Bore Stroker, T-56, Procharger F1A
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#5
Quote:Are you using ported or full vacuum?

i think edelbrock carbs use a ported vacuum.
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#6
Usually, If im using a vacuum advance distributor, I time it with it hooked up.

You need 36-40* total at @3000 RPM. You want lots of advance at low speed/cruising to make the engine smooth and fuel effecient. At WOT, you dont want as much advance. Thats why street cars have vacuum advances. It adds the extra timing based on engine demands.

The way I have set up my engines is to buy an advance weight spring kit and adjustible vacuum advance. Stock HEI distributors have 20* advancement on just the mechanical only. I usually swap springs around till I get full mechanical advance at about 3000 RPM.

Then you need to figure out what your initial should be. Low compression, regular fuel engines usually is between 6-10*. In high compression, 93 octane fuel cars sometimes need less. You will have to experiment with this so that you can get the best idle AND hot start performance.

Anyway, with the mechancal curved in right and you initial set, Its time to get you total timing in. You do this with the adjustible vacuum advance. You just set it to get your total timing. Now, if you got spark knock at part throttle, either you need to up your octane or pull some of your vacuum advance timing out. If you have sparknock/detonation at WOT, you either need to up your octane or pull out your mechanical( either by reducing your inital or put stiffer springs on the weights).

Or you can be like a racer and run a lockout distributor and have just 38* all the time (better have a really good battery and mini starter for that)Cool

Hope this helps
ASE Master Tech with 15 years experience


Daily Driver: 1994 GMC Sonoma, Extended Cab, 2WD, with the 4.3 V6 Vortec.
Future plans/projects: Finishing that darn 64 Malibu SS
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#7
Quote:i think edelbrock carbs use a ported vacuum.

One side should be full and the other should be ported.
2001 yeller Cobra, Ford GT fuel pumps, 80lb injectors, Bassani X-pipe, Borla Stingers, 323 Big Bore Stroker, T-56, Procharger F1A
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