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Discussion Starter · #1 ·
Wanted to throw this out there and see what the responses are. Simple question, get a case of engine run-on during the very hot summers. I'm aware of checking the initial timing and maybe backing off a degree or two, or re-checking air/fuel and reset the idle accordingly. I've never seen anyone mention a colder plug, or indexing the plug. Would this be an option? Or am I just dreaming?
Otherwise, it' a well running stock 289 in a '66 mustang.
 

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Timing from the book is for gas you can no longer buy. You must re-adjust your timing to modern gas. If you using a vacuum can on your dizy, disconnect it and plug it till you get your other timing in order.

You should be near 34 - 38 at 3000 RPMs, initial is not as important as your 3000 RPM timing.
 

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Hey groho,
I 'm running an autolite with a pertronix. I had it rebuilt and the curve plotted to provide "all in" by 3100-3200. My initial is 12 deg. with a total of 36 deg. Of course, the built in is 24 deg. This combo works great as the engine will accelerate with out any hesitation. I know a guy in MN who will check and adj your dizzy, if wanted. Not expensive at all. Contact me offline, if interestd.
Good Luck!
 

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Is the carburetor perkolating? You know dripping gasoline down the venturis when very hot and engine just got turned off.

Wm.
 

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How do you drive your car and in what type of terrain? What is your exhaust? It might be old backing up in the engine and making it work harder and run hotter. Radiator, what type, how old, how many rows? Hot engine mabye from weak radiator. Timing to far advanced, bad gas? To hot of spark plug. Change gas stations and see what happens. Then timing. Exhaust old, get new pipes and a little bigger, dual if you don't have it already. Clean out your gas tank unless it's new.
 

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Discussion Starter · #7 ·
Thanks for the input gang. Hate when I've gotta spend money and buy new tools: I see a new timing light in my future. . . and a MSD 6A, and a 4 core radiator. . . and a. . . .
 

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Discussion Starter · #8 ·
Hey FE, being next door, only you and I have a real good understanding of NORCAL valley heat, idling at a light, 105+ outside. Take care.... (at least it's a dry heat.)
 

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Running on can be caused by too fast an idle too. If you can set the idle lower without affecting the running of the car that will help. If you only have problems with it idling cold use the high idle adjustment near the choke to get it to idle faster when it is cold.
Set the idle speed as low as you can with the timing between 4 and 10 degrees BTDC. Use the idle mixture screws to get as high an idle as possible then repeat the process of dropping the idle with the idle set screw, play with timimng and idle mixture screws to get it to idle as fast as it will at that idle stop setting. If you can get it to idle smooth between 550 and 600 RPM it should have no problem with run-on.
Paul
 

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105 degs, you call that hot, I live in SW Utah, 118-122 is common in the summer. Just like Phoniex.
 

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PaulS1950 had some good tips. Also, if you have run-on only when it is hot, it seems the fuel is too hot. Do you have at least a one inch spacer below the carb? You need one to insulate the carb and to keep the fuel from boiling or perking.
Timing is important and if you can get figure it out, run premium during the hottest months.
 

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ONe other thing people (even me) have missed is that 99% of the time run on is cause by IGNITION in the cylindar...
Carbureted cars still have fuel entering the cylinders even after teh key is switched off.
If fuel were the main culprit then every car would run on/diesel...

His issue when it's hot out is in his combustion chamber... Something in there is igniting the fuel even after the key is off...
 

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It's probably the sparkplugs glowing a bit. Even after you cut the ignition it can still run the engine for a while.

I would also suggest a colder plug, or, at least filing the sharp edges off of the plug electrode.
 

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Discussion Starter · #16 ·
latest update... stang seems to be running better now then ever. Finished the exhaust, Doug's tri-ys, and flowmaster all the way back, and backed off the timing just a degree or two at 9 degrees initial. Immediately starts with a tap of the key, and shuts down with absolutely no stumbles. I suspect the headers may have corrected a rich condition. Now I gotta wait till summer to determine if this truely fixed the problem. Meanwhile, I'll redirect my attention to an auburn or eaton 3:25 posi rear-end. (sorry, chevy talk).
 
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