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PostPosted: Fri Jun 22, 2018 9:42 pm 
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Joined: Thu Oct 11, 2012 6:48 pm
Posts: 381
Location: Stamford, CT
Id try a half turn richer on both SU's first and then 93 octane to see if it helps. Is there any play in your distributor shaft?

While I've had a number of bad experiences with pertronix (due to voltage fluctuations), I do remember the timing being slightly retarded after my install.

I used a harbor freight (:shock:) timing light with an advance knob on the back. I disconnected the vacuum advance, set the timing light to 36*, screwed in the idle screw till it was idling at 3000rpm and adjusted the distributor until the timing mark was at 0*. Total timing is more useful than initial timing because it shows how much timing youre running at speed. If youre at 8* initial(or whatever the FSM specifies) but your potentially tired, old distributor mechanical advance only adds 5*, you would only be at 13* total timing vs the 36-38* most moderate compression L series engines can run.

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PostPosted: Thu Jun 28, 2018 9:00 am 
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Joined: Mon Jun 30, 2008 2:16 pm
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Location: Ansonia, CT
Thanks porkbun!

I'll have to get me one of those lights as I have no clue where my timing is at 3000 RPM.

Right now the car runs well. Since installing the Pertronix, I put new NGK BP6ES plugs in gapped at .035", new rotor, new wires, and new cap. The distributor, while old, has no shaft play (wobble). My only issue now is the pinging I get under load in 3rd or 4th gear.

I discovered a while ago that my distributor had only one spring on the mechanical advance. It must have been that way since new since I am the original owner of the car. I recently got another spring from Vinny Bedini but that spring is a bit weaker than the one in the distributor. I have to get a pair of matched springs and install them to see if that straightens out the advance curve. I think it gets too far advanced at higher RPM.

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PostPosted: Thu Jul 05, 2018 7:20 pm 
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Joined: Fri Dec 23, 2016 7:11 am
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We'll John, what did you find out?


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PostPosted: Thu Jul 05, 2018 10:02 pm 
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Joined: Mon Jun 30, 2008 2:16 pm
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Location: Ansonia, CT
I bought a new timing light and was able to check timing at idle and at 2000 rpm. I found timing to be too advanced at idle. I now have it set to 5 deg. BTDC at idle and 30 deg. at 2K. No more pinging, better acceleration but still have slight miss at low rpm under load. I think that is attibuted to erratic mechanical advance or wrong springs. I can live with it now. Heading to Motorfest 2018 early tomorrow about 325 miles. :thumbs_up:

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PostPosted: Fri Jul 06, 2018 4:19 pm 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 273
Thanks for the update, I'm glad she's not pinging anymore, that's hard on the engine. If you are missing under part throttle/low rpm it's possible there may be an issue with the vacuum advance mechanism. Might be worth a look.

Regardless, have fun this weekend John! Safe trip.

Jay


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PostPosted: Fri Jul 06, 2018 8:34 pm 
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Location: Ansonia, CT
Thanks Jay.
The car ran great on the drive to Rochester NY (343 miles).
Too bad you couldn't make this one. Weather is cooler and looks good for the Glen tomorrow.

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PostPosted: Fri Jul 06, 2018 10:40 pm 
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Glad to learn you made it ok John; disregard my message on your phone ~ you just answered my questions! :wink: :thumbs_up:

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PostPosted: Sat Jul 07, 2018 12:14 pm 
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I'm glad to hear you made it there safely and she's running well. Have a great time running Watkins Glen, that's a bucket list item for me!

The weather looks perfect this weekend, don't think you could buy weather any better!

Jay


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PostPosted: Thu Jul 12, 2018 6:44 pm 
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Location: Stamford, CT
johnnyZ wrote:
I bought a new timing light and was able to check timing at idle and at 2000 rpm. I found timing to be too advanced at idle. I now have it set to 5 deg. BTDC at idle and 30 deg. at 2K. No more pinging, better acceleration but still have slight miss at low rpm under load. I think that is attibuted to erratic mechanical advance or wrong springs. I can live with it now. Heading to Motorfest 2018 early tomorrow about 325 miles. :thumbs_up:


Glad the adjustable timing light helped a bit! Id also be suspicious of the distributor at this point too. Any parts store should be able to order you a reman distributor for the next day for about $120 with no core charge if you decide to go that route. I'm not sure how/when you drive but does it also ping at night or early morning in the cooler air?


Frank_T wrote:
I also now have some mysterious 'missing coolant' issue which I haven't been able to trace completely. About a gallon of coolant suddenly disappeared from the radiator (but is not in the oil), resulting in rising engine temps. I am hoping it was just my radiator cap allowing it to blow-over, but the cap is reasonably new.

Frank what coolant mix and what thermostat temperature are you running? There is an extensive thread on hybridz that I was just reading through about cooling and your post reminded me of this one. The thread can basically be summed up as:

"The path of coolant through the L engines results in the rear of the head receiving the hottest coolant having stagnated water flow, insufficient for the heat produced in the rear two cylinders and hence having the highest operating temps.

This can result in nucleate boiling at the rear of the head which can create a vapor barrier that slows the absorption of heat from the head to the coolant, making the #5 and 6 cylinders most likely to detonate."


Which is why a lot of people will drop valve seats(*hand raise*) or blow head gaskets on cyl 5 and 6. Remedies include:

"1) Drill and tap above the #5 and 6 exhaust ports and route coolant to the thermostat housing generally below the thermostat to retain it's control on proper warmupto improve the flow of coolant at the rear of the head. Some have gone further and include #3 and 4, and some have even tapped all 6.

2) A higher pressure radiator cap can help reduce nucleate boiling.


3) The L28 diesel water pump can be made to fit and improves coolant flow.

4) Tapping and plugging the block to stop coolant flow from bypassing the thermostat (and hence radiator) helps devote more flow THRU THE ENGINE, but make sure that some path exists during warmup the #1 mod above is done to avoid water pump cavitation before the thermostat opens.

5) Non-aqueous coolant helps preventchanges when nucleate boiling occurs, and generally results in much higher operating temperatures across the board which may have other detrimental under-hood effects.

6) Water wetter seems to help in most cases,through decreasing surface tension of the coolant, very similar to a higher pressure radiator cap not so much in others."


I think I heard some pinging at high speed/high load the other day so I'm going to try a 160*F thermostat and some water wetter. If that doesnt work ill swap caps for a higher pressure unit I think mine is 11 or 13#s?

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PostPosted: Sat Jul 21, 2018 7:35 pm 
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Joined: Mon Jun 30, 2008 2:16 pm
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Location: Ansonia, CT
Well, after much fiddling with the timing, and evaluating the overall performance of the PerTronix ingnitor system, I have decided to go OLD SCHOOL again. Yes, I put the points back in! :shock:

I just could not seem to get the Z's timing set to the sweet spot that would prevent low end missing and high end pinging. I also didn't feel confident that the PerTronix unit wouldn't leave me stranded some day due to what I feel are some basic design issues. These include, what I think, is the rather poor way the module wire leads need to be routed within the distributor. I noticed some chafing of those leads where they enter the distributor and interfere with the edge of the moveable base plate when the the advance is exercised. I also found it difficult to arrange the leads to prevent rubbing on the magnetic collar or the rotor. I found myself constantly removing the cap to adjust the leads to prevent them from being damaged by the internal moving parts of the distributor. :roll:

PerTronix support did respond to my "performance" questions in a timely manner, but after doing all the suggested resistance, grounding and voltage checks without finding any issues I decided to go back to installing the points. The breaker points have NEVER let me down in the 47 years I have owned the car. I didn't have that same confidence with the PerTronix unit. I also fiddled a bit with the advance spring tension to improve the effectiveness of the mechanical advance at low end. The end result is the car now runs great! No more missing at low end and no pinging at high end. :thumbs_up:

Besides, there is something in my pea brain that still seems to make me feel that properly setting the points is a skill I don't want to lose. :wink:

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PostPosted: Sat Jul 21, 2018 10:38 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
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Location: CT
Well now, this is very interesting.

The Pertronix system is expected to be an improvement in performance, reliability and ease of service (as in, NONE until it quits). If it is causing my high end breakup issues it's not worth it to me to keep it in there, either. I don't experience any low-end problems (in fact I love to lug the car from rest in 2nd gear, reminiscent of the old Healeys) but we have played with all moving parts in an attempt to keep my car from breaking down before 7K rpm, and the best I can reach is 6500 when all the planets are aligned.

I'm aware of the danger of the Pertronix unit simply quitting without warning. The old points used to deteriorate and run rough before they quit, giving you a few days to find replacements. The Pert will just QUIT without warning (so I'm told) so I bought and carry a spare unit everywhere I go ($100 when I bought it). But if the Pert is what's causing my high-end breakup, I don't want it.

Bryan Little used an MSD system on his L28 and it carried him beyond 7,000 rpm whenever he wanted it to. AirJockie used an MSD on his 260 drift car and it carried him up to 8,000 several times :shock: (and it was street-legal).

Thanks John ~ you might have saved me a lot of hunt-n-peck diagnostics. I hate buying and trying new spark plugs because they are so costly and it takes so long to try each heat range at several gap sizes, but that was what I thought might be happening when the ignition stuttered above 6,000. I'm replacing the engine in my car this zeason (about the ONLY thing I'm doing with my Z this zeason :roll: ) and this would be the right time to replace the points and condenser system.

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PostPosted: Sun Jul 22, 2018 9:29 am 
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Joined: Mon Jun 30, 2008 2:16 pm
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Location: Ansonia, CT
Frank,

Keep in mind that my goal is to preserve my old Z and keep it streetable and reliable. Frank, your goal may differ in that you seem to be striving for higher performance. While that might be nice for me as well, I have learned over the years that many "performance modifications" used to achieve that goal usually means sacrificing something else, like reliability, driveability or ease of maintenance.

Since my car did run reasonably well with the Pert for 962 miles driving to and from the Rochester event, (including the laps at the Glen), I always had this concern that the Pert could interfere with the trip. It did not. I've heard both good and bad things about the Pert. Tom Bork, who races that nice yellow 240Z at the Glen still uses points :shock: as he has had issues with a Pert unit before. It comes down to what works best for your driving goals. In my case, I no longer beat my car up that much (now with 185K original miles), typically limiting shifts to 6K or under . If I were you, I might still consider the MSD option.

Don't forget that I also tweaked the tension on my advance springs which may have had the biggest effect in fixing my timing problems. I guess tweaking these old "dissy's" on a Sun Tach is becoming a lost art. Some of the new electronic distributors can be custom programmed to meet the exact timing curve requirements of your engine, something that is pretty tough to match by adjusting both the mechanical and vacuum advances.

Oh, and regularly starting off in second as you know may cause your clutch to wear out faster. :wink:

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PostPosted: Sun Jul 22, 2018 11:26 am 
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Location: CT
["....may cause your clutch to wear out faster. :wink: "]

Yeah, Vinny scolded me for that twice. He could see I had been doing that by "reading" the clutch.

But it's such fun and throws me back 50 years to my Healey days.....I just love to hear the low-end howl and torquey build-up from low revs. It's a childish thing, I admit, but I like it.

And anyway, as things are going recently, I get the chance to change out my clutch and T/O bearing every 3,000 miles or so anyway! (3 times in 10 years). :roll:

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