Home » Public Forums » GMCnet » Which is better, HEI or points?
| Which is better, HEI or points? [message #362017] |
Wed, 27 January 2021 18:53  |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
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This should start some conversation.
The very fact that good, dependable, modules and coils are hard to find makes me want to swap my HEI for points. And points will go all the way down to barely running before they fail.
This is an interesting article that may surprise some folks.
https://www.hotrod.com/articles/ccrp-9812-ignition-performance-test/
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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| Re: Which is better, HEI or points? [message #362021 is a reply to message #362017] |
Wed, 27 January 2021 19:38  |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
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First distributor type HEI is not maintenance free as they state. Cap and rotor are still wear items and any weakness in the system will cause components to fail prematurely. Also the 50,000 Volts or what ever number they want to put in a coil ad is rarely achieved. Once the spark jumps, voltage rise decays. The pickup in HEI is simply more accurate than mechanical points and not a wear item. I think they would need to test several stock points distributors and several HEI units and average the results to get better data. Also the advance curves will never match exactly and a degree will change HP and TQ graphs s lot. I have nothing against points to get you home reliably. I still have them in the Onan and it always runs.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Which is better, HEI or points? [message #362023 is a reply to message #362017] |
Wed, 27 January 2021 20:12 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Greg C. wrote on Wed, 27 January 2021 19:53This should start some conversation.
The very fact that good, dependable, modules and coils are hard to find makes me want to swap my HEI for points. And points will go all the way down to barely running before they fail.
This is an interesting article that may surprise some folks.
https://www.hotrod.com/articles/ccrp-9812-ignition-performance-test/
Greg,
That is an interesting survey, but in typical marketing fashion, they left out the simplest and least expensive option.
This is why I push new owners of any points controlled GM engine to slide a Pertonix 1181LS in there. In the marine applications, I tell them keep the old points in a jar as a back up. I tell them this for their own confidence, not mine. I have never replaced a Pertonix set that was not mechanically damaged (usually by mis-handling).
If you think you want to fire the plugs harder, find a real CDI. MSD will do, but I have replaced two of the low end units and one was mine.
Thing I like about this plan is that when my own MSD box shot craps in the middle of the night and 5 hours from home, I just pulled it out of the system and then pulled all 8 plugs and hammered them back to 0.035 from the 0.060+ were I usually run them.
When I got home, I went into my junk box and got out a Delta MKX (circa 1974) an put that in where the MSD was and opened the the plugs back up.
Small caution here...If you want to do the 0.060+ trick, get good wires and be ready to replace the cap and rotor. The stock Delco cap will survive and many aftermarket will not, but get the best silicon wires you can find.
I used to carry a replacement HEI module and coil to back up friends, but my last one has not been replaced. (There is hope still.)
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Which is better, HEI or points? [message #362026 is a reply to message #362024] |
Wed, 27 January 2021 22:14 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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The system that Larry mentioned is a great way to replace the old points
and condenser that need to be replaced after 12,000 miles., Also that unit
creates as much dwell as the HEI and will have stronger spark.
Should you understand know how to field replace the Module and coil, it is
a good set up.
On Wed, Jan 27, 2021 at 6:30 PM Larry via Gmclist
wrote:
> Just an add-on to what Matt said, there are two varieties of the Pertronix
> system that will work in our distributors. The 1181 and the 1181LS...the LS
> is for "Lobe sensing". The LS version senses off of the lobes that opened
> and closed the old points. The 1181 is designed with a ring of 8 magnets
> that fits in under the rotor. Each magnet is the "trip" for the coil. I
> had one of the magnets work it's way loose and take out the sensor that was
> bolted where the points were. Fortunately it happened in my driveway, not
> on the road. Took me a while to diagnose it when suddenly...no spark. In
> the mean time it acted like in a points distributor, the points were
> closed passing current to the coil. Boiled the coil and took it out also.
> Anyway,
> make sure when/if you do this conversion that you get the lobe sensing
> (LS) version, and maybe get the matching "Flame Thrower" coil. JFWIW
> --
> Larry
> 78 Royale w/500 Caddy
> Menomonie, WI.
>
> _______________________________________________
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
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| Re: Which is better, HEI or points? [message #362037 is a reply to message #362017] |
Thu, 28 January 2021 11:42 |
kingd
Messages: 592
Registered: June 2004
Karma: 2
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The GMC content is related to what was said above about never having to replace a Petronix thatjust failed without external cause. Many Formula Ford racers replace the points in their race cars because the Petronix still meet the strict Formula Ford rules. I have personally witness. A Petronix equiped car would not run properly. Swapping the distributor for one with points and the engine ran fine. If I used a Petronix, I would definitely have some kind of back up. This is not the only time a Petronix in this application supposedly just "failed"
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
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| Re: Which is better, HEI or points? [message #362039 is a reply to message #362037] |
Thu, 28 January 2021 11:57 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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kingd wrote on Thu, 28 January 2021 12:42The GMC content is related to what was said above about never having to replace a Petronix thatjust failed without external cause. Many Formula Ford racers replace the points in their race cars because the Petronix still meet the strict Formula Ford rules. I have personally witness. A Petronix equiped car would not run properly. Swapping the distributor for one with points and the engine ran fine. If I used a Petronix, I would definitely have some kind of back up. This is not the only time a Petronix in this application supposedly just "failed"
Dave,
I would love to know what the issue really was. While reading this, I was trying to total the number of Pertonix I know of (most, I did the install). I lost track somewhere. Not all Pertronix are equal. Remember the 1181LS vs 1181 remarks? When first looking at these devices, I was wondering about Lenz's Law and the Faraday Effects that I know well of from electric machines. Early on, I decided that they would be there in the realm of "Point Float" that I knew of from the race car days in prior years. (Why we had to go to a Mallory shutter system when close to 10500 RPM.) I don't think I will consider that a problem for any GMC application.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: Which is better, HEI or points? [message #362064 is a reply to message #362017] |
Thu, 28 January 2021 21:19 |
kingd
Messages: 592
Registered: June 2004
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MATT, THE "failed" Petronix that I saw would start and run but had a big misfire. I think that when most racers have a problem with a Petronix they just throw the "bad" one away. I wished at the time that we had a scope to show us what was going on. I'd think a SUN Engine Analyzer would be just the tool to show what was happening
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
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| Re: [GMCnet] Which is better, HEI or points? [message #362067 is a reply to message #362064] |
Thu, 28 January 2021 21:38 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Adding a bit to Matt's original post: I've never used a Pertronix on a
vehicle engine, but I was one of the first to install it on the Onan, using
the original 1181, with the magnet-laden rotor. The 1181LS came along
later and is not suited, AFAIK, to use on the Onan (we mounted one of the
magnets on the flywheel as the trigger). IF I were going to run a
Pertronix-equipped Onan and a Pertronix-equipped engine distributor, I'd be
inclined to stick with the 1181 since it would enable me to carry only one
spare for the two of them.
That's purely gratuitous advice since I run HEI on my Cad500 and a TroyBilt
generator. :-)
Ken H.
On Thu, Jan 28, 2021 at 10:20 PM Dave King via Gmclist <
gmclist@list.gmcnet.org> wrote:
> MATT, THE "failed" Petronix that I saw would start and run but had a big
> misfire. I think that when most racers have a problem with a Petronix they
> just throw the "bad" one away. I wished at the time that we had a scope to
> show us what was going on. I'd think a SUN Engine Analyzer would be just
> the tool to show what was happening
> --
> DAVE KING
> lurker, wannabe
> Toronto, Ontario, Canada
>
> _______________________________________________
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> Unsubscribe or Change List Options:
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: Which is better, HEI or points? [message #362071 is a reply to message #362017] |
Fri, 29 January 2021 09:04 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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I put a lobe sensing unit in my 69 GS400. Keeps stock look and I retained the factory resistor wire. Idle is noticeably smoother. Points and condenser are in a baggie in glove box. Car is not plated and Polyglas tires are 45 years old so no WOT testing has been done. But revs nicely in park.
John Lebetski
Woodstock, IL
77 Eleganza II
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