Topic: WHAT DID I WRONG ?
in Forum: C3 Engines
Thanx all for new idees !!! 
I'll try them out if i didn't it already .
O my god ,Dave , you started it !
Very interesting new view on vacuum advance.... all guys changing from ported to manifold ??? 
Oeps, i hope there will be NOT many new "what did i wrong" threads....
Don't shoot at me ! , DAVE started it ! 
I can only give some advise : for those with running C3's WAIT untill the C3 gathering at PF to convert any otherwise it could be a lonely happening for a happy few.....
Lifetime MemberThe statements in the article you found are absolutely true. I discuss this in even more detail in my classes. Temperature also comes into play. It also changes the rate of fuel burn in the cylinder. Peak cylinder pressure (not spark) should be at 10 degrees after top dead center. But the fuel must be lit before that to achieve that number.
But some engine will still do well with the ported vacuum advance. It has to do with design of the cam, compression, and even more, the fuel mixture the carb is designed to provide at different throttle openings. Bottom line, it's a great article, but if you have a stock carb and cam, and the car originally had a ported vacuum advance, as most do, keep the ported vacuum.
There are several production cars that do use manifold vacuum, but the carb and timing curve are set up to take advantage of that setup. Most of our cars do not.
Right Ken, that's what i tought. Starting with manifold vacuum needs a differerent mechanical set ... and there whe go...
Had not so much time but what i did :
regulated the valves at 1/2 turn instead of 1 turn. Problem remains the same , but i hear a small different noise in running idle. Perhaps i give them 1/4 turn extra ???? to total 3/4 ???
Even moving and bending them a litle i checked all wiring in distributor with ohm meter and they "seem" OK.
Put I plug wire about a half a inch from it's socket on the distributorcap and noticed : idling there are perfect lightings jumping across but reving they become less and less visible untill nothing...
Put a volt meter on the coil primary : idling i have about 9 volts and reving it drops to 2 / 3 volts ????? is this normal ???
Perhaps the BEAST 
is ignition past 3000 rev's ?
But why ???? and do i need special equipment to check that ?
thanx guys for advise.
Sounds like you are on to something...
When you say 2/3 volts, do you mean "2/3 of 1 volt" or "2 or 3 volts"? Belgian to english loses a little in translation.
Like I said, I have not fooled with points-type distributors in a long time. Does yours have a primary resistor dropping coil voltage? If so jump around it and see what happens. Better yet, run a wire directly from the battery (or big hot starter pole) directly to the "BATT" side of the coil and see if the pufpufpufpufs go away. Neither temporary step will hurt anything.
Dave
Just as an additional reference. There is a resistor wire from the ignition switch to the coil to make the coil run at about 9 volts. So that voltage is correct. When the car is started, the ignition switch supplies power to another wire the bypasses the resistor wire. This supplies full battery voltage to the coil.
There are a couple of reasons. As the battery is cranking the engine, voltage drops below 12 volts. When the car is running it's about 14 volts due to the charging system. This means with a fixed voltage to the coil, the spark would be much weaker at cranking than running. With the resistor wire, the coil produces much closer to the same spark strength at cranking as it does when running.
This stronger spark at crank, helps the car to start easier, and more dependable. If the coil was built for the 12 volts without the resistor wire, spark at crank would be much weaker. If it was a 9 volt coil like used with the resistor, during normal operation the spark would be stronger, but the coil would overheat, burn out, and fail.
You can see the difference in some coils. They often list specs for an internal resistance or and external resistance. With or without the wire. Switch them back and forth either way and you have a problem.
If voltage is checked at the coil positive with either setup, as long as the points are open you will read battery voltage. An open circuit in a series circuit will read source voltage before the open. In this case the open circuit would be the points.
With the coil grounded, or points closed, the difference can be easily measured with a meter. The resistor wire set up will show lower voltage. But leaving the coil grounded too long can cause damage.
And the voltage reading will vary on a running engine due to the dwell. The more the points are closed, the lower the voltage. The less the points are closed, the highter the voltage. Keep in mind this is measureing at the coil positive.
A running engine will often read close to 12 volts, or slightly higher. 14 volts source volts will show 14 when the points are open, and 9 when they are closed. This produces an average reading on a meter. And the reading will vary depending on what type of meter you are using. But usually you will see 12 or slightly more.
Now back to yours. I agree that you can run a hot wire to the positive side of the coil for a short term test. If the problems clears up you may have too much resistance in the coil power supply due to corrosion or a poor connection. If the change is small, or does not exist look at the other side of the coil.
If the point are at .016 gap you should be close to correct dwell of 30 degrees. The dwell meter is the better way to go. If you have a performance or non stock distributor the dwell should still be 30 degrees, but the gap could be much different.
It really does sound like you are losing primary voltage when you rev the engine. Due to the fact it is relative to engine speed, I suspect a problem with the points, condenser, or distributor ground.
Translate the 2/3 for us if you would. I didn't follow that either.
I didn't realize they still had resistor wires in the '70s. That thing gave me fits on my '59 Chev 6-banger when I went to the HEI ignition on a 292.....
Never knew the reason for the resistor wire till now...
Dave
The HEI won't use the reisistor, but the points will.
When you convert them just go to the igntion switch, and run a new wire along the resistor wire, and bypass it. Then the HEI works fine.
That's what I ended up doing, many, many moons ago...
'59 Chev Biscayne coupe with 1970 292 I-6 TBI injected dump truck motor, still surprises a lot of small-blocks... sounds like a herd of hormets on the dragstrip.
Dave