Pertronix Ignition and Timing

[Beemon]

5 minutes ago, carbking said:

Drill them oversize 0.002 inch. Reassemble, readjust idle, and try an additional 2 degrees initial timing.

 

Jon.

 

How hard is this to do without a drill press? Probably an idiot question, but I don't have access to any type of shop. Timing is already advanced an initial 2 degrees.

 

In my defense, I did run the car two weeks on ethanol free premium with no visible difference in performance.

[NTX5467]

You can probably use "twist drills" which can be found at many hobby shops (at least that's where I got mine).  They should come with a holder that is hand-held.

 

This is how I go the idle system to work on my 1980 Carter BBD 2bbl, but not quite so scientific as the dimension Carb King mentioned.  I just went until I "got brass" and stopped there, cleaning out any accumulated deposits that were restricting the "low speed jet" (what they called the drilled orifice in the bottom of the idle tube) and not letting enough fuel into the idle system for it to work.

 

Getting a cam as aggressive as the Nailhead cam to "work" at the lower rpm idle speeds of that time can result in lower intake manifold vacuum at idle and "idle speed wander".  This can be due to residual exhaust remaining in the combustion chamber at the lower idle rpm level, think "built-in NoX reduction".  This can make the normally-decently-rich idle mixture more diluted and harder to get fired-off (which the additional timing might help get done).  Just a thought.

 

An ignition coil (even the "hot" ones, with a higher total potential voltage capability) will only produce the amount of "spark" needed to fire the spark plug.  At idle, the demand on the system is low, but as soon as load is added, the requirement will suddenly increase.  Therefore, having a 50KV oil on a stock system is acceptable as it's not going to produce 50KV UNLESS it needs to.  Kind of like an engine not producing full-rated power "unless it needs to or is motivated to".

 

Is there a speed shop with a chassis dyno in the area?  Or a high-level tune-up shop with a similar (but lower power capacity) chassis dyno where you could strap it down on the rollers and watch the emissions output at idle, during "the stumble" (even using the "one-foot" driving technique), and at 55mph cruise.  Their equipment can probably also monitor ignition functions during all of this, too, I suspect.  Something of this nature might be needed to get things better adjusted on your vehicle.  OR at least watch the instrumentation and see what might be happening with the emissions output and the ignition system.

 

NTX5467

[Beemon]

For the life of me I cannot find my multimeter. I did however go for a night drive tonight (admittedly to the local Taco Bell... that stuff will kill you) and when I pulled into the driveway, I was a little bit curious.

 

I revved the engine first, with heavy bogging at idle in Park, and the headlights flickered noticeably. However, when I eased into the throttle, the headlights didn't flicker at all. So at this point I can safely assume that it's most likely an electrical issue. Would the ignition system draw that much power on acceleration to dim the headlights or should I look into replacing the generator in the near future or both? I'm still looking for my multimeter to check coil resistance and continuity, but I think I can safely sideline the carburetor for right now.

[carbking]

If one is going to work on lots of item (eg carburetor idle tubes) requiring drilling, a set of orifice drills is very handy to have. The set that I have ranges from number 40 to number 80. Each drill has its own handle, and one can use these with one's fingers - no power drill required. They are available through suppliers of parts/tools for furnaces (when a furnace is converted from propane to natural gas the burner orifices must be enlarged). These drills are fairly expensive for the hobbyist only wishing to use them once.

 

For the hobbyist only wishing to drill the idle tubes in one carburetor, a set of number drills from 61 to 80, and a "pin vice" will suffice. The pin vice will have a few different size collets to allow grasping the different size drills. Again, the pin vice may be rotated in one's fingers, no power drill necessary. The pin vice/number set is less convenient than the orifice set with the individual handles, but MUCH LESS expensive.

 

And, a bit more information: for those wishing to enlarge carburetor main metering jets (larger than the idle tubes), the number set of number 1 to number 60 is useful; HOWEVER one will find there are gaps in the coverage. As an example a number 54 drill is 0.055 inch whereas the next size in the set number 53 is 0.059 inch. These gaps may be reasonable filled (although not absolutely) by ordering fractional metric drills. I have yet to see a set of these (and if one existed, is would be EXPENSIVE as there would be lots of drills) so one should first select the number 1 to 60 set, and then order individually the fractional metrics one needs.

 

Jon.

[carbking]

And one caviat concerning the above post.

 

I have heard all my life the old wives tale (actually, it is an old husbands tale, old wives are smarter than this  ) about drilling and re-soldering main jets to tune as needed. DON'T BELIEVE IT!!! Regular solder is sufficiently soft that gasoline going through the drilled and soldered jet would erode all of the solder from the jet in one pass down the drag strip, just like the Missouri River erodes the levies that people erect to attempt to harness the river. Guess where the solder would end up?

 

On the other hand, silver solder would be sufficiently hard, but virtually impossible to drill in an accurate fashion.

 

If you drill too far, you must replace the jet.

 

Jon.

[60FlatTop]

Old wives tails are more fun. Back in 1968 I spent some of my Navy off-duty time studying an ICS (International Correspondence Schools) course on Automotive Tune-Up and Carburetion. I was planning my career as an automotive mechanic after the Navy. I still have a few of the books in the garage. While rolling along through the South China Sea I became increasingly annoyed at detailed instructions on the drill size to modify air bleed tubes on 1949 Plymouth carburetors, the intricacies of 1951 Oldsmobile two barrel drilling and the like. Details of obsolete stuff, and I already had experience without these fabled clinical activities, ended up it me dropping the course. I never did pursue a career as an auto mechanic, but as a hobby I sure did a lot with carbs. And the closest I got to any solder was digging out the plugs in the bottom of a Q-Jet to put a fresh seal in.

If one can pick up each part of the carb and know its name and what it does the rebuild will probably bring it back to the performance level it left the showroom with. Sometimes long periods of setting (not going to write idle) take their toll. Metering rod pistons come to mind right away. The point is having to understand carburetors are not a scientific process. They are art. The differences in density of air and fuel, and the streams, flows, and eddy currents formed can be random, not as predictable as one would like. Then put it on an engine (pump) with not so predictable flow characteristics, it's lucky most run as well as they do.

Then the manufacturer designs it to bristle with easy to access adjusting screws to tempt the owner. That's just a ploy to get you to mess it up and bring it back for service.

 

Check everything twice, then check everything that isn't a carburetor. When you are absolutely sure it's all correct, check it all again.

Bernie

Edited June 12, 2016 by 60FlatTop (see edit history)

[old-tank]

6 hours ago, Beemon said:

For the life of me I cannot find my multimeter. I did however go for a night drive tonight (admittedly to the local Taco Bell... that stuff will kill you) and when I pulled into the driveway, I was a little bit curious.

 

I revved the engine first, with heavy bogging at idle in Park, and the headlights flickered noticeably. However, when I eased into the throttle, the headlights didn't flicker at all. So at this point I can safely assume that it's most likely an electrical issue. Would the ignition system draw that much power on acceleration to dim the headlights or should I look into replacing the generator in the near future or both? I'm still looking for my multimeter to check coil resistance and continuity, but I think I can safely sideline the carburetor for right now.

The flickering could be from the charge rate dropping during the bog or stumble due to low RPM OR a momentary short in the system causing the ignition to drop out.  Watch the amp meter.

We had a rebuilt engine in a 55 that stumbled and died on left hand turns but would start right up afterwards.  Turned out the engine moved just enough to short the  battery cable at the starter against the splash pan...repositioning fixed it.  In this case the amp meter did not help.

Willie

[Beemon]

Okay so under protest, I dropped the car off at the 'family' shop under recommendation from my father. They were supposed to make sure brakes front to back were set up correctly and leak free (I already knew they were, parents...). While the car was in, I asked them to check continuity because I just could not find a multimeter and I'm already having to pay for the shop fee to have them remove my drums and put them back on without touching anything else.

 

Turns out at some point my vacuum advance stopped working. Anytime the butterflies are opened, it causes a vacuum leak through the diaphragm and creates a really lean condition off idle, this is where the stumble is more than likely coming from. I've also learned that there is some type of short in part due to my heater fan motor. They couldn't duplicate it when I was there to pick up the car and told me to see an electrical specialist because they don't do electricity of that magnitude (basically just plug wires and coils). They also tightened the brake shoes way too tight. I had to drive home on the freeway and I kept smelling this awful burning smell, only to get home, jack a wheel off the ground and have it barely turnable (was always told a half revolution, that's where I had it before and the car stopped fine). I think they also advanced my timing and richened the carburetor to compensate for the vacuum advance failure, but I haven't checked timing yet.

 

I don't want to do anymore troubleshooting until I have replaced the vacuum advance. I'm not keen on buying a NOS vacuum advance as the rubber will most likely be the same condition as mine - brittle and develop a hole again. The only place I can seem to find that sells them is Kanter, with a $45 deposit and a $85 price tag, Fusick at $79, and Bob's at $102. Has anyone had any experience with these vendors? I'm assuming they're all rebuilt units with modern diaphragms.

 

The other alternative is to find a later nailhead distributor and curve it to the 56, but I'd rather not.

 

Also thanks again for all the support guys!

[NTX5467]

To me, main things to be concerned with in a "replacement" vacuum advance is the amount of advance it provides (length of the arm going to the breaker plate and where the travel limiter is on that arm) and when it starts (minimum vacuum level).  Most of the replacement items are adjustable for when the advance starts, so the main consideration is the length of the arm and where the travel limiter is compared to the current vac advance unit.

 

Now, you also know that your brake linings are more "cured" than they used to be.  BE SURE to check the parking brake cable adjustment, too!

 

Take care,

NTX5467

 

 

 

 

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[Guest COMPACTBC]

I had a Pertronix  system on my 64 Riviera and while I was on a trip to Flint MI it started acting up while approaching the Eisenhower tunnel.  So when i got to the Flint area I had it removed and went back to the stock system and I have never had anymore problems. 

 

 

 

 

 

 

 

[60FlatTop]

I just got the new Cadiilac-LaSalle Club Self Started magazine yesterday. It looks like there is a pretty good article on the 4GC's and WCFB's in there. I didn't get a chance to read it but the pictures were clear and detailed.

 

On that .002 office size; that's a whisker. So I had to check:

From the US department of Energy.

 

1 gallon of gasoline equals 5.8 to 6.5 lbs.

1 gallon of ethanol equals 6.59 lbs

 

Interesting gasoline has a wide range and ethanol is exact to a hundredth.

 

And then figure you are getting 10% ethanol at the pump

 

A few years ago I was using some 20% plus in my truck, equipped with a FlexFuel system. It is a 2005 and flashed to monitor specific gravity at the time it was built. I was driving about 40,000 miles per year. I went through a lot. The mileage suffered a lot but was not consistent. Performance was poor and I threw a code on the evap system. I chalked it up to inconsistency in the ethanol. Maybe the reference tables recognizing the fuel were incorrect due to the variations of the gasoline and not the ethanol. I quit using it and economy and performance returned.

 

Anyway, questioning the resizing of the bleed opened some new thoughts for "windshield time". Calculating the range of specific gravity in varying mixtures and the ranges of gasoline sp. gr. really make fuel injection look good. That's for sure.

 

Any Caddy Club members have a .pdf of the article?

Bernie

 

[Beemon]

So this pay period, I bought a multimeter. Vacuum advance will be here on Wednesday, but my coil read 1.5 primary resistance and 10.5k secondary resistance, which is way out of spec. I went down to NAPA yesterday to pick up a replacement coil and it was about the same, 10-11k ohms on the secondary. The shop manual says 6500-9000 secondary resistance, I'm assuming the higher resistance decreases the voltage across the plug wires and spark plugs and is also to blame for poor performance. There isn't any mention in the manual about what being over or under the stock resistance is supposed to be so I guess I'll be shopping for a "high performance" coil since these over the counter ones seem to be junk. I haven't even gotten to check the capacitor yet, but I'm assuming that one is also garbage. Any suggestions for quality replacements?

 

Also happy 4th of July!

Edited July 5, 2016 by Beemon (see edit history)

[Joseph P. Indusi]

Your ignition coils may be OK.  The resistance of 10K in the secondary is pretty close to 9K, and the slightly higher resistance may be due to more turns of fine wire in the secondary coil that will produce a higher spark plug voltage.  I would suspect the capacitor (condenser), the wire inside the distributor connecting the points to the exterior terminal for the wire going to the coil or some other wiring irregularity.   Set the timing at idle by the book and then connect the new vacuum advance and see what develops.

Joe

[SpecialEducation]

35 minutes ago, Joseph P. Indusi said:

Your ignition coils may be OK.

 

Agreed.  The voltage input/output is based on the primary/secondary winding ratio, not the resistance of each side.  Ohming it out tells you if you've got an open or short winding, but you have to keep technology differences in perspective.  Not just in your meter, but in the coil itself.  Unless you are testing an original, 60 year old, Delco coil, I'd call those numbers ballpark.  An aftermarket coil may have more windings or a different gauge of wire, which would change the resistance, while still maintaining the same winding ratio. They look close close enough to me, I'd focus my efforts elsewhere.

[Beemon]

Okay so I passed the coil off as good.

 

Checked the condenser, .20 uF, in good shape (I think shop manual said .18-.23 uF?).

 

I got my vacuum advance today, so I swapped the old one out for the new - will be sending the core back tomorrow.

 

On to spark plugs - AC R43S.

 

Boy, the research I've done on these is that they replaced the OEM AC 44 plugs, and they suck. I went and ordered NGK 5858 V-Power plugs and it made a world of difference.

 

With new plugs, coupled with the new vacuum advance, the car has zero hesitation anymore. My idle vacuum raised from 16" to 19-20" as well. I am really happy here. I'm going to have to re-adjust the 4GC since I had to richen it up just a little bit to compensate for the leaking vacuum advance, but it didn't feel like it was running rich at all. They say the NGK V-Power plugs use half the energy to arc, so maybe it's arcing more than it needs, but regardless this car is running better than ever. I was so impressed, it completely changed my attitude about the Rochester from "well, it's a Rochester, they bog off idle" to "the carburetor works just fine".

 

Thanks for all the help everyone, I think I can finally put this thread to rest.

Edited July 8, 2016 by Beemon (see edit history)