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Discussion Starter #1
Hi Folks - after exchange my Autolite 4100 to an Summit 600 Racing Carb I have one Question. I hooked on a Vacuum Gauge and it displayed I have a little bit late ign. timing. It´s nearly from the red to the green Zone on my Gauge. Exact the Frontier...

How can I solve this? Loosen the Distributor Base Screw and twist the Whole thing to leave red "late ign.timing"?

If so - should Hose from the Diaphragm Canister be on or off?
Which Size does the Screw on the Distributor Base have?

And another Question: There are two Tools for align the Timing. Timing light or Vacuum Gauge...correct?

Olli
 

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Galaxz posted good info. To expand things a bit, I'll mention what is done sometimes when your running a bigger cam in your car but it also works with a stock cam. Connect your vacuum gage to the intake manifold and disconnect & plug the line to the distributor. Also connect your timing light. While the engine is running, slowly advance the timing until you get the highest vacuum reading then back off the timing 1in of vacuum on the gage. Ck to see where the timing is with your timing light. Go for a road test and see if it spark knocks. If it does, back it off 2* and drive it again. This method gets your engine to run at its best without being stuck to factory specs.
 

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Galaxz posted good info. To expand things a bit, I'll mention what is done sometimes when your running a bigger cam in your car but it also works with a stock cam. Connect your vacuum gage to the intake manifold and disconnect & plug the line to the distributor. Also connect your timing light. While the engine is running, slowly advance the timing until you get the highest vacuum reading then back off the timing 1in of vacuum on the gage. Ck to see where the timing is with your timing light. Go for a road test and see if it spark knocks. If it does, back it off 2* and drive it again. This method gets your engine to run at its best without being stuck to factory specs.

All good for setting initial timing but off idle spark knock would most likely need mechanical advance mods. Todays fuel likes more initial and less total. Dialing in the initial and mechanical advance to optinum then the vacuum advance needs addressed. Most often it will need to be reduced from adding 15 to 20* to only adding around adding 5*.
 

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on older engines, a reliable way to set timing is with the vacuum guage. This is because timing chains stretch. Turn the distributor to maximum vacuum, then turn back one inch of vacuum generally gets it as good as it can get.
 

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Just a reminder, that changing one part of the ignition advance curve changes all points that are mapped into the mechanism. As it is a mapped mechanical mechanism, changing one end of the spectrum changes the other, and everything in-between. Finding best idle timing is excellent :tup:, but if you do that, you need to repeat the exercise at increasing rpm and loads to re-establish the best settings under those other conditions. You should be doing that for best performance and mileage anyway, so no biggie. Just be aware; if you (for example) increase idle timing, you must, at a minimum, also reduce maximum timing to re-establish that point. Else, you will have an awesome idle, but a botched curve (incorrect timing) at all other points above that.

One change affects the others. If your engine only ever idles, then you can safely ignore this, and you're fine.

David
 

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Discussion Starter #8
thanks for your Comments - dear Co-Enthusiasts...My Question was if I can hook on a Vacuum Gauge, see what the Indicator says.. The Frontier of late ign. timing and the green field indicates that the Situation is normal.

I tried to experience a bit whith my Vacuum Gauge to align the Idle Mixture Screws as best I can.

Is it not possible to set the Ignition point out of the red field of the "late ign. Time" by twistin the Distributor Base?

Just want to learn...

Olli

My Timing Chain is quite new and I do not have a knock in any kind...
 
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