Points ignition vs electronic

General engine tech -- Drag Racing to Circle Track

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Geoff2
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Re: Points ignition vs electronic

Post by Geoff2 »

The problem with points triggering HEI [ or any ign system for that matter ]:

- points bounce
- rubbing block starts wearing the first time the key is turned, retarding ign timing
- points contact surface erodes, can change timing &cause misfires.

There is absolutely no reason to use points to trigger HEI because the HEI pick up coil is extreeeeeeeeeeeeemely reliable & the pick up/trigger mechanism very accurate, cyl to cyl.
DrillDawg
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Re: Points ignition vs electronic

Post by DrillDawg »

Geoff2 wrote: Sat May 19, 2018 8:15 am The problem with points triggering HEI [ or any ign system for that matter ]:

- points bounce
- rubbing block starts wearing the first time the key is turned, retarding ign timing
- points contact surface erodes, can change timing &cause misfires.

There is absolutely no reason to use points to trigger HEI because the HEI pick up coil is extreeeeeeeeeeeeemely reliable & the pick up/trigger mechanism very accurate, cyl to cyl.
Sure there is, even msd says you can. Some of those guys might want to make their old bikes look stock and you can hide the hei module anywhere you can transfer the heat out of it. It just depends on what you are doing and why. And it depends on how cheap you want to be.
BORN RIGHT THE FIRST TIME
user-23911

Re: Points ignition vs electronic

Post by user-23911 »

I used points with a self built transistor ignition many years ago. Back then there wasn't an easy conversion to get rid of the points. It was a Ford 272.
The result of that combination was a better spark and more RPM before it started to misfire.

Going forwards to the 21st century, a distributor is outdated, wasted spark or COP is the clever way to go and all the bits can be found in the junkyard for very little expense.
Really need EFI which means getting rid of the carburettor too, another bonus.

It comes down to money and effort required.
If you're just a parts changer then an HEI is easiest.
hoodeng
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Re: Points ignition vs electronic

Post by hoodeng »

I should have qualified my post Truckedup , you are right the impedance used by different manufacturers vary to their own systems requirements.

The only product i work on is American V twin ,the impedance's effects i was referring to related to their pre 1980 ignition systems. Electronic ignition was a godsend for this product, and for any points installed product for that matter.

Cheers.
user-23911

Re: Points ignition vs electronic

Post by user-23911 »

"Impedance" is the wrong word.
What you measure with an ohm meter is resistance.
Impedance is an AC terminology, the difference is the impedance changes with frequency.
Resistance doesn't.

If you're using a 0.5 ohm coil and a 2.5 ohm ballast to give 3 ohms total, the initial current when the circuit is first completed is zero. That's because the coil is an inductor. Because there's no current, there's no voltage drop across the ballast.
The rise in current with time is determined by the time constant L/R. Final, as in max current is determined by R.
As the current rises with time, less voltage is dropped across the coil and more is dropped across the ballast.
So in order to correctly spec the ballast, you really need to know L, the inductance of the coil.
The main but not only purpose of the ballast is to prevent the coil from burning up when you turn on the ignition but don't start the engine.
hoodeng
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Re: Points ignition vs electronic

Post by hoodeng »

Definition
impedance


Impedance, denoted Z, is an expression of the opposition that an electronic component, circuit, or system offers to alternating and/or direct electric current.Impedance is a vector (two-dimensional)quantity consisting of two independent scalar (one-dimensional) phenomena: resistance and reactance.

Joe,
I may be using it in the wrong context though.

Cheers.
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Re: Points ignition vs electronic

Post by Truckedup »

hoodeng wrote: Sat May 19, 2018 9:00 pm I should have qualified my post Truckedup , you are right the impedance used by different manufacturers vary to their own systems requirements.

The only product i work on is American V twin ,the impedance's effects i was referring to related to their pre 1980 ignition systems. Electronic ignition was a godsend for this product, and for any points installed product for that matter.

Cheers.
I thought it was likely a Harley.......About 25 years ago I had a modified Shovel head with dual plug heads...I used a dual point plate to fire each cylinder separate..Had two dual outlet coils, one to each set of points..One or the other plug on each cylinder would foul....The dual outlet outlet coils were not designed to fire two plugs under compression at the same time..So I wound up just grounding one spark plug lead and running the engine as a single plug because I didn't know that then..
Motorcycle land speed racing... wearing animal hides and clinging to vibrating oily machines propelled by fire
inline6
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Re: Points ignition vs electronic

Post by inline6 »

What I have found on the tractor side of things. If you run points you better have good tight bushings, with EI that tolerance is more forgiving on the shaft. I find better cold starts probably due to the greater energy to the coil. Also have noticed in recent years like everything else points quality material has suffered causing faster wear.
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The only replacement for displacement is RPM!
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Re: Points ignition vs electronic

Post by PackardV8 »

Yes, it's getting difficult to find good quality points, condensors, rotors, caps. Most of the available supply today is Chicom and of variable reliability.

Those of us who are forced to work with the old stuff have to find interchanges for GM/Delco and Prestolite/Mopar which will work on Studebakers and Packards.
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Truckedup
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Re: Points ignition vs electronic

Post by Truckedup »

PackardV8 wrote: Sun May 20, 2018 2:03 pm Yes, it's getting difficult to find good quality points, condensors, rotors, caps. Most of the available supply today is Chicom and of variable reliability.

Those of us who are forced to work with the old stuff have to find interchanges for GM/Delco and Prestolite/Mopar which will work on Studebakers and Packards.
15 years ago I bought carton of Delco points and condensers on Ebay for pennies on the dollar... Not any more as prices have gone up... NOS condensers may be not so good after 25 years on the shelf. large electronic online dealers sell all sorts of capacitors of .20-.25 microfarads...Just mount them externally close to the distributor..
All my junk is electronic now..
Motorcycle land speed racing... wearing animal hides and clinging to vibrating oily machines propelled by fire
user-23911

Re: Points ignition vs electronic

Post by user-23911 »

I think what you want is more in the order of 10 to 100 nanofarads (not microfarads) but just going from memory here.
JCR
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Re: Points ignition vs electronic

Post by JCR »

PackardV8 wrote: Sun May 20, 2018 2:03 pm Yes, it's getting difficult to find good quality points, condensors, rotors, caps. Most of the available supply today is Chicom and of variable reliability.

Those of us who are forced to work with the old stuff have to find interchanges for GM/Delco and Prestolite/Mopar which will work on Studebakers and Packards.
On another forum I'm on, a long time Ferrari mechanic said that by the late 1970s OEM Marelli replacement points for the earlier Ferrari engines were junk because the tooling was worn out. Just another reason to convert to electronic.
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