Surge problem at speed

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Mattax said:
The only way to know what the timing looks like in an aftermarket distributor will to measure the timing at various rpms and then plot it.
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And while yur doing that,with the V-can disconnected, watch yur timing marks as you momentarily snap the throttle open; the strobing better not; go out, back up, or go wonky! The timing should advance smoothly.
 
famous bob said:
PETRONICS HAS A SET UP THAT WILL FIRE MUTPLE TIMES THU OUT THE RPM RANGE TO 10,000 RPM !
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IDK about that. Even MSD fades to 1 after about 3300 RPM due to the sheer speed of the coil charge/discharge capability.
 
davidcribbs said:
I adjusted the timing, although the car seemed to run better at almost 15 degrees initial timing, which according to your thread sounds a little high? Since I didn't build the engine, I am not sure if it has a cam or not. I did plug the vacuum line when timing it, but that sounds like quite a bit of initial timing. No detonations, and seemed like it wanted more. Any thoughts?
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Engines always idle better with more initial, sometimes up to 30 degrees.
But in your case, you can't give it that much Idle-Timing. Because;
1) the starter probably won't crank it, and
2) anytime you change the IdleTiming, ALL other timing points also change, and
3) your PowerTiming could be high enough to rattle your piston skirts straight into the oilpan. and
4) extra timing will often band-aid a carburetion issue. Fix the carb, and you can back off the timing.
5) stale fuel will cause all kinds of strange manifestations under anything but steady-state operation. I rate freshness by 5 colors
1) Clear is Fresh .
2) Yellow is still usable; works Ok in your Injected DD, but a carbed car is in distress; some of the Vocs have evaporated, and she won't like transitioning
3) between Yellow and Orange, is not good for a carby; most of the VOCs have evaporated and so she will be hard to start, hard to keep running until warmed up, and she hates to transition from idling to anything else.
4) Orange is best left to your push-mower..... if it will start. All of the Vocs have evaporated, and the mower will need a carb adjustment but, with a sharp blade you can still mow.
5) Red is useless, go ahead spill some on a concrete floor and try to light it. If you can even get it to burn, it will smoke and sputter and leave an ugly greasy mess on the floor.

15* of Idle-Timing for your 360 is not too much, but also not required, and you will have to limit your Power-Timing back to about 34* by around 3200 rpm. If your 360 wants that much, she probably has a fueling issue.
The thing is, with that much timing, the throttle will be nearly closed with a stock/stockish cam, and the transfers will be slow to come alive on throttle tip-in, leaving you with the hesitation you mentioned.
A bog is a different deal, this can happen when the throttle is slammed open at a much faster rate than the tip-in. And this is almost always an accelerator pump issue, usually pump-timing. On most carbs the pump has to be readjusted after any major curb-idle adjustment.
 
You probably had at least two problems, one of which is fixed.

Ign problem sounds solved. Factory timing figures are conservative because the use of the car is unknown at the time of sale. If your engine 'likes' & runs better with 15* init, doesn't ping, then leave it there. The extra timing could be the result of a large[r] cam fitted previously. It would probably be a good idea to have the dist re-curved with the centri curve reduced if you stick with 15* init.

If a bog occurs when the throttle is opened, it is leanness. Need to know more about the bog. Happens with light or heavy throttle? Just off idle? Or further into the rpm range?
 
Once I had a similar problem. Water in the fuel was the answer. At low rpm
The fuel delivery was minimal but at
Much higher rpm more was sucked up off the bottom of the tank. That’s why I wont stop for gas if I see a tanker truck
At the station. I should have figured it out as the problem was interremittant
As it were I started using a gas station as gas was cheap there and then I had consistent problem.
 
pishta said:
IDK about that. Even MSD fades to 1 after about 3300 RPM due to the sheer speed of the coil charge/discharge capability.
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They even say so in their literature. Or at least they used to. They say up to 20 sparks. But the first one cannot come until triggered.
At Idle, the spark could be triggered to occur at say 16 Degrees. If the mixture is too poor to light or to poor to stay lit, then the hope of the Multi-strike, is that one of the following sparks will light it and keep it lit. But each one of those is a retarded spark. And so peak pressure in the chamber occurs later and later. But at least, your muffler doesn't fill up with a misfired and combustible mixture...
If the poor mixture gets to be burning stably in the following few degrees, then work will be done. But if it takes more than a few degrees, then the pressure comes too late, and the crank feels it. If it's only one weak-azz powerpulse, every once in a while, you might never know it. But if the carb has a problem and several cylinders in a row are weak, then you might interpret it as a surge as the engine goes into and out of the power commanded by the position of the gas-pedal. If both primaries are having a problem , the symptoms could be more severe. The same symptoms could occur by any other means that could produce a lack, or drop, or interuption, of signal to the primaries, like; air leaks, tight valve lash, or an overly active scavenge cycle, a faulty or missing PCV system, or a ruptured booster diaphragm/broken control valve. And of course contaminated or stale, fuel
The thing is, if the engine was NOT blessed by a Multi-Strike, the carb problem would be obvious.

I gotta tell ya, I have had very good success with the Accell, Square-Top HD coil. It has been faithfully firing my 367 with an ancient 750DP atop the Airgap, with every cam this combo has run including the 292/292/108 Mopar, even from 500 rpm to 7200, the highest I have shifted. That thing fires a big fat long-duration spark in open-air that sounds like a welder. I power mine up straight off the battery thru a 10ga wire, thru it's designated ballast , relayed by the ignition switch.The voltage at the coil with a hot resistor is a tic over 9.5 volts. We donneedno steenking multi-strike, the first one never misses.
 
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Ahhhhhhhh, yes. The Pert 'multi sparks' through out the rpm range. All contained in a small module that fits inside the dist....


When I emailed Pert & asked them if the system was inductive or CD, they did not reply.
And no other company has a similar m/spark module that I am aware of. Funny that.

Unless Pert knows something that nobody else knows, there is not enough coil charging time with ind ign to provide m/spark at higher rpms. And not very high rpms either, perhaps 3000rpm limit.

That leaves CD ign. it requires a hefty transformer & large-ish capacitor which would not fit in a module. Box is needed like MSD boxes.

So, hmm. has Pert 'invented' something new that nobody has thought of?

Wouldn't MSD & other companies open up the magic module to see how Pert 'did' it?

You would think so because lots of $$$ to be made....
 
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