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Old 05-05-2009, 11:28 AM   #1
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
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Join Date: Jan 2007
Member Number: 10
Location: Leaburg, Orygone
Age: 71
Posts: 7,156
Default "Ignition Power Timing"

We've discussed this deal I refer to as "power timing" in other threads around here. This a method of optimizing ignition base timing for your engine running the fuel type you use every day. It does not involve the use of any kind of timing light or "specification". Once this procedure is understood and performed, ya can go back and shoot it with a timing light and see whatcha ended up with timing-wise.

It's still imperative to use a timing light when performing many diagnostic procedures.

Purdee simple...only after setting dwell (or breaker point gap) to the required spec (or the correct "air gap" if an electronic pickup is being used), loosen the distributor hold down enuff to allow rotation by hand with considerable force applied. If the distributor has not been touched in decades onna I-4 or sv, don't be surprised to find it frozen in place due to mung and a century of ratpiss rainin' on it. That's a whole other issue to deal with!

We also gotta assume here that the distributor guts are in nice shape, mechanical advance is free and not worn out, the end play is minimal, the breaker plate rotates smoothly when called upon, the vacuum advance system is functional, ya don't have a dam prestolite cap onna Holley or vice-versa, blahblahblah...

All this rhetoric is also based on the use of whatever passes for "regular" grade alkeegazz in yore market and a carburetor that is in "average" condition with no jetting issues. This shit has nuthin" to do with electric carbs or what Craig calls "efi" and all the hocuspocus that goes along with that, I don't need no dam pooter fookin' with my sparkmaker when goin' down the road!

Crank tha motor and run it fully up to temp...that means git the oil hot...not just the coolant temp!

Then rotate the distributor slowly for and aft (all these IH motors when used in motor vehicles rotate the distributor clockwise), as ya "retard" (or as I sumtimes say..."back off") the timing, then the idle rpm will drop. If ya "advance" the timing (or as I say, "kick it up") by rotating the distributor, then idle rpm will increase. Do that several times to get the "feel" for what's happening, but not so far either direction that the engines stalls. It's not possible to cause any kind of engine abuse when doing this!!!!

If it does stall, then put the distributor back where it was, re-start tha motor, and do it again! Do not leave the ignition switch "on" without the engine running! If you are running almost any kind of electronic trigger conversion, that can damage or fry the part. If ya do that with breaker points, they will quickly overheat and go through meltdown! If you are running a sooperdooper ignition "box" with an electronic trigger, most of those incorporate an internal circuit that turns them off after a slight period of inactivity for protection. So ya might have to go through a "switch cycle" or "as you pootercar drivers say, "key cycle", for 'em to come back to life.

So after ya gotta feel for this distributor rotation thang...simply rotate it to increase idle rpm to the point the motor starts sounding kinda rough and "gallopy", that's too much base advance! Back off from that point until is smooths out and sounds like the motor in yore table saw! Do not screw with any carb adjustments here!!! We ain't done!

Now just go out for a test drive! And yes, I do this with my hearing aids installed, otherwise I can't listen for/hear what we call "knock" which izza fanceeazz term for detonation!

So...if ya "advanced" the distributor to the right spot, as soon as ya nail the loud pedal hard, yore gonna be greeted with major ping! That is good, that means ya did sumthin'! But that is now yore starting point...the fun begins! Don't do this with the whole famdambly in the rig, they will git bored real quick! And do it out on sum back road where ya kin stop and go and stop and go and stop and ...over and over, and pull off the right of way to make "adjustments" on the fly.

So the whole idear here is to keep doing this over and over until the ping/detonation/spark knock is eliminated under full and partial throttle app, when the engine is under load. Then back off the timing a scoshe more for "insurance" against fuel octane variables that occur every time ya fill up.

Bet ya find the sob is much more peppy! But it dam shore won't pass smog! For instance...a "typical" sii/304 package will have a base timing "spec" of say zero degrees btdc, ya can see that on the smog sticker under the hood if it's still there...or look in the book. If ya use the described methodology, and then hook up the timing light, I bet ya will see somewhere between six and ten degrees btdc. This procedure is not smog compliant!!!!!

Ya ain't done...make dam shore ya snug down the distributor now at yore new sweet spot! Then...ya will also notice the curb idle speed is way too high. Back off the curb idle adjustment, onna sv motor with manual tranny, I use 550>600 rpm. With a tf 727 tranny, I use 700 in park/nuetral.

Now ya can touch up the idle mixture screws on the carb, and ya will have to keep ditherin' the idle speed at the same time. I bet ya find that the idle mixture screws end up landin' inna totally different position! This is why ya only screw with a carb after the ignition system is completely locked down! If ya wanna use a vacuum gauge for this, then that's even better so ya can see what is going on.

And after some more test drives if ya pull the plugs for a color check, ya May see a need for a slight re-jet of the carb also if you wanna get it ragged edge!

Let me reiterate...this is performance tuning and is not in the same ball park as tuning for smog or to oem "book" specs. If...your rig is totally original, and all "smog devices" are functional and connected properly, in other words basically a virgin, then this procedure is not in your best interests.

However...if ya did put this rig onna smog machine ya might be real surprised at the final numbers! Too bad the "air quality" folks just don't get it, who gives a shit if the dam cat is installed if the fookin' numbers show it's runnin' clean????
Are yawl ready??? If not here's some training ya might need to prepare:

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