Over the years there has been confusion over the various contact sets sold by NAPA under the Echlin brand. There are a total of six applicable to Delco single point distributors not including the "uniset" that combines the points and condenser in a single assembly. NAPA also sells a price leader line called Mileage Plus and a couple of other sets in different brands.
You can see them all at www.napaonline.com
TDB member and NAPA jobber Tim Schuetz of Waukesha, WI also wanted to get to the bottom of it, so Tim sent me four of the six part numbers for analysis in boxes marked CS86, CS89, CS786P, and CS7860.
Armed with a three-pound spring scale, mic, caliper, multimeter, and plain screw driver to partially disassemble the breaker arm leaf springs for measurement, I offer the following measured and visual observations. A summary of the measured data follows the discussion. All have screw type terminals rather than using the breaker arm spring to secure the wires like the old Delco D106P, a design I never cared for, but the old Delco D106PS has a screw terminal.
Achieving consistent breaker arm tension readings required a little practice, and I found than listening to Bach during the measurements improved consistency.
CS86: This set is listed on the Web site as "standard" and is equivalent to the OE points installed on single point Corvette distributors before '73 when the uniset became OE. The breaker arm tension is speced at 19-23 oz., and in addition to the main leaf spring, which is non-magetic or just slightly magnetic indicating stainless steel, there is a thin parallel leaf that appears to be copper and is likely there for conductivity. It is too thin to add breaker arm tension.
CS89: This set is listed on the Web site as "high performance" and appears identical to the CS86, but main breaker arm leaf is .002" thicker, which increases breaker arm tension to equal the 28-32 oz. of the long-discontinued Delco D112P.
CS786P: This set is listed on the Web site as "vented", but the set in the box was not vented and is most likely the CS786 discussed next. Other than the perforated contact pads, the CS786P is likely identical to the CS786. Vented points have been around for decades, and the theory is that they run cooler, which extends point life, but I have no personal experience and have never seen a scientifally conducted test.
CS786: This set is listed on the Web site as "heavy duty" and has larger contact pads, which increases contact area by about 43 percent. Also, the breaker arm is a different design - different geometry - which made measuring breaker arm tension difficult, but it's basically the same as the CS86.
CS7860: This set is also listed on the Web site as "high performance", and has the same spring thickness and breaker arm spring tension as the CS89, but it has some different construction details. The other three sets' breaker arm springs are retained to the breaker arm by a 90 degree tab that fits into a slot in the breaker arm. This set has no tab. Rather, the end mounted to the breaker arm is longer allowing it to be secured to the breaker arm with the rivet that retains the rubbing block. It does not have the thin copper parallel spring, but I could find no difference in resistance with my ohmeter that measures to about 0.1 ohm. All are essentially zero to 0.1 ohm resolution. The insulator is red rather than white on all the others, and the adjustment spring has blue Loctite.
This set also has another interesting feature. Packaged with the capsule of grease is a small felt pad with a slot. The slot fits over the rubbing block, and the instructions say to grease both the rubbing block and felt pad. This should help retain grease and should be included with the other sets in my opinion. Despite this extra feature and what appears to be somewhat more robust construction, this is the least expensive set of the six!
CS7860C: This set is listed on the Web site as "racing only", and I suspect it has higher than 32 oz. breaker arm tension. Since the 32 oz. sets will go to at least 7200 revs in a snug distributor, this set should not be necessary for any road-going Corvette with something close to an OE engine configuration.
Part.........Spring.....Spring...........Contact.. ...Web site..............Online
number.....tension,...thickness,......diameter.... comment.............price
...............oz..........in.................in.
CS86........24..........0.018/.006.....0.152".......standard..............$16.49
CS89........32..........0.020/.006.....0.152".......high performance...$21.49
CS786......24...........0.018/.006.....0.185".......heavy duty..........$15.69
CS786P....---...........----/-----......------......vented................$16.49
CS7860.....32..........0.020/---.......0.152........high performance...$14.99
CS7860C...---.........-----/---........-----........racing only...........$16.49
My basic usage recommendations are as follows:
1. Engines with redlines up to 5500 and the 1.8 ohm ballast - CS86.
2. Engines with redlines up to 5500 and the 0.3 ohm ballast - CS786. The additional contact area might reduce the tendency to burn up points, which is not uncommon on systems with the 0.3 ohm ballast, especially in cold weather. Ballast resistance decreases with decreasing operating temperature and vice versa.
3. Engines with redlines over 5500 - CS7860. This set is less expensive than the CS89 and has some better features.
Proper distributor operation is necessary for peak engine performance - everything from idle quality to making it to the redline with no spark scatter or ignition breakup. It's possible that if you have a freshly blueprinted distributor, a standard tension set will make it to 6500 in a mechanical lifter engine, but in my experience, maximum high rev performance in mechanical lifter engines requires a 32 oz. set. As with many tuning parameters, what works in your distributor for you boils down to the condition of your distributor, your driving habits, and maybe some experimentation. My bet is that a majority of single point distributors out there are in need of a blueprint overhall, which has been discussed on the TDB many times. If the ignition system doesn't deliver a properly timed spark of sufficient energy for all engine operating conditions, the engine will never achieve peak performance and fuel economy. It's that simple!
Nominal point life is about 30K miles, but can vary widely depending on ignition system configuration and condition. Since most of our cars have low annual mileage accumulation, it's a good idea to check that there is still some lubrication for the rubbing block at least every couple of years, and while you're at it, check point resistance and dwell angle. Dwell angle changes will effect initial timing, so checking initial timing is also a good idea after you have you checked and, if necessary, adjusted the points. Throw in the idle speed/mixture adjustment procedure and you've done a "minor tuneup" in less time than a wash job.
A hearty thanks to Tim Schuetz who said he doesn't want the test samples back. My plan is to auction off the CS86 and CS786 at our So. Cal. Chapter meeting next month and donate the proceeds to the chapter, but for the time being, I'm going to hang on to the CS89 and CS7860.
Duke
You can see them all at www.napaonline.com
TDB member and NAPA jobber Tim Schuetz of Waukesha, WI also wanted to get to the bottom of it, so Tim sent me four of the six part numbers for analysis in boxes marked CS86, CS89, CS786P, and CS7860.
Armed with a three-pound spring scale, mic, caliper, multimeter, and plain screw driver to partially disassemble the breaker arm leaf springs for measurement, I offer the following measured and visual observations. A summary of the measured data follows the discussion. All have screw type terminals rather than using the breaker arm spring to secure the wires like the old Delco D106P, a design I never cared for, but the old Delco D106PS has a screw terminal.
Achieving consistent breaker arm tension readings required a little practice, and I found than listening to Bach during the measurements improved consistency.
CS86: This set is listed on the Web site as "standard" and is equivalent to the OE points installed on single point Corvette distributors before '73 when the uniset became OE. The breaker arm tension is speced at 19-23 oz., and in addition to the main leaf spring, which is non-magetic or just slightly magnetic indicating stainless steel, there is a thin parallel leaf that appears to be copper and is likely there for conductivity. It is too thin to add breaker arm tension.
CS89: This set is listed on the Web site as "high performance" and appears identical to the CS86, but main breaker arm leaf is .002" thicker, which increases breaker arm tension to equal the 28-32 oz. of the long-discontinued Delco D112P.
CS786P: This set is listed on the Web site as "vented", but the set in the box was not vented and is most likely the CS786 discussed next. Other than the perforated contact pads, the CS786P is likely identical to the CS786. Vented points have been around for decades, and the theory is that they run cooler, which extends point life, but I have no personal experience and have never seen a scientifally conducted test.
CS786: This set is listed on the Web site as "heavy duty" and has larger contact pads, which increases contact area by about 43 percent. Also, the breaker arm is a different design - different geometry - which made measuring breaker arm tension difficult, but it's basically the same as the CS86.
CS7860: This set is also listed on the Web site as "high performance", and has the same spring thickness and breaker arm spring tension as the CS89, but it has some different construction details. The other three sets' breaker arm springs are retained to the breaker arm by a 90 degree tab that fits into a slot in the breaker arm. This set has no tab. Rather, the end mounted to the breaker arm is longer allowing it to be secured to the breaker arm with the rivet that retains the rubbing block. It does not have the thin copper parallel spring, but I could find no difference in resistance with my ohmeter that measures to about 0.1 ohm. All are essentially zero to 0.1 ohm resolution. The insulator is red rather than white on all the others, and the adjustment spring has blue Loctite.
This set also has another interesting feature. Packaged with the capsule of grease is a small felt pad with a slot. The slot fits over the rubbing block, and the instructions say to grease both the rubbing block and felt pad. This should help retain grease and should be included with the other sets in my opinion. Despite this extra feature and what appears to be somewhat more robust construction, this is the least expensive set of the six!
CS7860C: This set is listed on the Web site as "racing only", and I suspect it has higher than 32 oz. breaker arm tension. Since the 32 oz. sets will go to at least 7200 revs in a snug distributor, this set should not be necessary for any road-going Corvette with something close to an OE engine configuration.
Part.........Spring.....Spring...........Contact.. ...Web site..............Online
number.....tension,...thickness,......diameter.... comment.............price
...............oz..........in.................in.
CS86........24..........0.018/.006.....0.152".......standard..............$16.49
CS89........32..........0.020/.006.....0.152".......high performance...$21.49
CS786......24...........0.018/.006.....0.185".......heavy duty..........$15.69
CS786P....---...........----/-----......------......vented................$16.49
CS7860.....32..........0.020/---.......0.152........high performance...$14.99
CS7860C...---.........-----/---........-----........racing only...........$16.49
My basic usage recommendations are as follows:
1. Engines with redlines up to 5500 and the 1.8 ohm ballast - CS86.
2. Engines with redlines up to 5500 and the 0.3 ohm ballast - CS786. The additional contact area might reduce the tendency to burn up points, which is not uncommon on systems with the 0.3 ohm ballast, especially in cold weather. Ballast resistance decreases with decreasing operating temperature and vice versa.
3. Engines with redlines over 5500 - CS7860. This set is less expensive than the CS89 and has some better features.
Proper distributor operation is necessary for peak engine performance - everything from idle quality to making it to the redline with no spark scatter or ignition breakup. It's possible that if you have a freshly blueprinted distributor, a standard tension set will make it to 6500 in a mechanical lifter engine, but in my experience, maximum high rev performance in mechanical lifter engines requires a 32 oz. set. As with many tuning parameters, what works in your distributor for you boils down to the condition of your distributor, your driving habits, and maybe some experimentation. My bet is that a majority of single point distributors out there are in need of a blueprint overhall, which has been discussed on the TDB many times. If the ignition system doesn't deliver a properly timed spark of sufficient energy for all engine operating conditions, the engine will never achieve peak performance and fuel economy. It's that simple!
Nominal point life is about 30K miles, but can vary widely depending on ignition system configuration and condition. Since most of our cars have low annual mileage accumulation, it's a good idea to check that there is still some lubrication for the rubbing block at least every couple of years, and while you're at it, check point resistance and dwell angle. Dwell angle changes will effect initial timing, so checking initial timing is also a good idea after you have you checked and, if necessary, adjusted the points. Throw in the idle speed/mixture adjustment procedure and you've done a "minor tuneup" in less time than a wash job.
A hearty thanks to Tim Schuetz who said he doesn't want the test samples back. My plan is to auction off the CS86 and CS786 at our So. Cal. Chapter meeting next month and donate the proceeds to the chapter, but for the time being, I'm going to hang on to the CS89 and CS7860.
Duke
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