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Points Gap, Dwell, & Timing

I've been experiencing a bouncing tach as the revs increase. The other day I experienced a sudden power shut-down, for only a second or two. Tach dropped like a stone, all electrical power seemed to be off, like somebody threw a switch. Then the car started right up again. Pulled the distributor cap, cranked the engine through by hand. Points are at MUCH less than the .016 the book calls for, couldn't detect them opening at all.. Called mechanic...he told me he doesn't pay much attention to points gap, but worries more about correct dwell. Okay, now I'm wondering... I have neither a dwell meter or a timing light, wouldn't feel confident using them if I did. I do feel I could set the points to .016 without extending my limited skills too much. I'm beginning to think these too close points could be the cause of the bouncing tach and the sudden shut down. Question? If I set the points to .016, & clean them by running clean paper through them, and change NO other settings, could I hurt the engine by changing the timing or dwell? Oh...the car seemed to be running great, other than the sudden shutdown...
Old 06-30-2003, 04:05 PM
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you will probably have to reset the timing. That can be scarey as you set it at 6000 RPM! But it is something you can do yourself with ease. This also sounds like forplay to the CD box taking a dive, Mine did the same thing then died for good till I replaced the CD box.
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Old 06-30-2003, 04:20 PM
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HuH! What does he mean that point gap does not mean a thing to him. On my 72, when my tach started slowing down and would not keep up to engine revs, I regaped the points and that went away. Plus my car ran better. Regap them andcheck to see if they are pitted as well. I bet your probs go "Bye Bye". But you should also check dwell after you set points if you have a meter that does this. I don't, car runs great.
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Old 06-30-2003, 04:23 PM
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Paul,

Point gap and dwell angle setting are tied together unconditionally! Set your gap to 0.014" and the dwell angle will be in the center of its' range, too! No dwell meter needed!

Timing should be checked/set after adjusting the point gap ... of course!
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Old 06-30-2003, 04:32 PM
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Thanks to all! I live 80 miles from the nearest decent Porsche shop...so, if I set points at .014...then drive to the shop with no timing or dwell checks. Have both set to specs. Odds of any engine damage... Slim? None? Some? High?
Old 06-30-2003, 04:42 PM
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Hello everyone...I dont mean to interrupt...but this brings up a question:

My tach bounces all over the place at any rpm, before settling into the correct reading of rpm. I thought it was a problem with the tach... is that not necessarily the case?
Old 06-30-2003, 04:51 PM
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Sonic! Where ya been. How come you took the Tele off your signature? Got me a 51 Tele/P bass two weeks ago...verrrrry bad A$$ bass!
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Old 06-30-2003, 04:57 PM
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pwd - did your points come loose? why is this sudden -- that's the question to figure out. Try cleaning the pts. for sure first. used to file them but now just toss them out if worn or pitted.
Old 06-30-2003, 05:06 PM
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Paul, I agree with Warren, over the course of the last two years I sound that setting the points gap at .014 vice .016 gets me close to nuts on dwell range. Pick yourself up a timing light at Sears that measures dwell as well. They are dang easy to use after a couple of laps around the points gap, dwell chack, timing routine. Seems like it take me a couple of iterations to get it absolutely right. For the experts, is the closer gap a result of the distributor beginning to wear over time? Paul i also found that a dag of bosch dist grease makes the points last a LOT longer.
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Old 06-30-2003, 05:35 PM
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BTW - thanks again for the help with the radio info! Gotta love true Porsche people!
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Old 06-30-2003, 05:46 PM
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Warren is right, of course. Dwell is the number of degrees that the points are closed (I think...or open...anyway...), so you see, the gap determines the dwell and vice versa. When you use a dwell meter after you have set the gap, you are fine tuning the gap. It is usually a bit off. Often, the points are too far open.

And if you think about it, you can see how changing the gap will also change the timing. A decent automotive test meter is a pretty necessary tool. They usually measure voltage, dwell and also resistance. Finally a decent timing light is pretty necessary too, if you're going to work on cars.



As for bouncing tachs, some say this is always caused by a bad voltage regulator, but I disagree. My tach is bouncing and has for some time, before and after an engine rebuild and an alternator rebuild. It bounces when I hit a bump. My starter sometimes won't operate too. When this happens, I wiggle the square plug next to the engine compartment fuse panel and then it starts. I know my starter problem is caused by a poor connection there. I suspect my tach symptom has the same cause.
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Old 06-30-2003, 06:10 PM
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Be very careful with a dwell meter around that Bosch CD and coil!
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Old 06-30-2003, 06:24 PM
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Good practice is to re-gap during each oil change according to my mechanic who cut his teeth on the early models. With new points it seems that the fiber block will wear down a bit before seating in. The bosch lube on the lobe is a critical ingredient here. Two great tricks I learned back in my British car days was to carry a business card to set the gap if you do not have a gap tool and use a dollar bill to clean the points if pitted and leaving you stranded. The business card is about as close to .014 as you can get without the tool. The dollar bill might just get you home one day! What do you think, about a 1500 grit?

My once in a blue moon jumping tack?................the infamous green wire!!

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Bob
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Old 06-30-2003, 06:49 PM
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i installed a pertronix ignitor electronic points that i bought here a few months ago and the car starts immediately, runs great and the tach works. i like to know that i dont have to fool around with the points and dwell anymore. and i set the timing and have no problems.

a good under 100 dollar item in my opinion.
gary
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Old 06-30-2003, 06:53 PM
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Paul,
Follow Gary's lead and lose the points. Timing is related to point gap and point gap never stays consistent due to rubbing block wear. There are many options for going pointless (Pertronix, Crane, etc.). Once installed and timing set, your timing light will gather dust and your ignition timing will remain.

Sherwood Lee
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Old 07-01-2003, 11:38 AM
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I have the Crane unit in my 70 S and I love it! Set it and forget it!
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Old 07-01-2003, 11:45 AM
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I'm pretty sure Paul's car is stock (Original) and meant to be that way. I don't think he would want to change a thing on that beauty. But, I could be wrong-as usual.
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Old 07-01-2003, 11:47 AM
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Paul, I agree w/ Sherwood and Gary, there is no reason on earth to keep points on a driven car in this day and age. Especially being 80 miles from the mechanic w/ no diagnostic tools and little in the way of tools/DIY interest. The only concievable reason for points would be a concours/originality issue, (relevant w/ your car), but the conversion that we are mentioning is 100% reversible. Just keep the original stuff in a box. Also, I believe that it does not change the appearance of engine bay.

In the meantime, I agree w/ previous advice, but I think that if you reset gap your timing should be unchanged, assuming that all was set to spec at last adjustment.
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Old 07-01-2003, 11:51 AM
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Targa??? In your 70s with the Crane Unit. What crane unit are you using and did you have to connect the white wire from the crane to your new Pertronix Ignitor? Was the Installation easy???
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Old 07-01-2003, 01:41 PM
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decision reached

Called Jeff Gamroth this morning...I'm going to join the breakerless ignition brigade. Since my original '72 distributor is one of those with the "backwards" points, I'm going with a new RS distributor, breakerless opically triggered. It'll go in sometime next week...I'll keep the original distributor, may even have it rebuilt. But yeah, I'm not totally hooked on originality...
Hang in Chris, the photocopies should be there in a few days. Hope they are what you were looking for.

Last edited by pwd72s; 07-01-2003 at 02:12 PM..
Old 07-01-2003, 02:04 PM
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