Replacement Coil and Spark Plug Wire Questions

[content22207_2]

My thoughts are Bosch coil terminals have confused people for decades:

BoschCoilTerminals1.jpg BoschCoilTerminals2.jpg BoschCoilTerminals3.jpg BoschCoilTerminals4.jpg

Bosch may have added + and - signs later, but an old Volkswagen mechanic told me that they used to only be labeled 1 and 15.

As long as the end user wires his coil up correctly, what does it matter? I've helped owners who wired up coils backwards, which doesn't work well at all. However it's marked, 15 or +, just make sure that's where White/Yellow is attached.

Bill Robertson
#5939

[PJ Grady Inc.]

My thoughts are Bosch coil terminals have confused people for decades:

BoschCoilTerminals1.jpg BoschCoilTerminals2.jpg BoschCoilTerminals3.jpg BoschCoilTerminals4.jpg

Bosch may have added + and - signs later, but an old Volkswagen mechanic told me that they used to only be labeled 1 and 15.

As long as the end user wires his coil up correctly, what does it matter? I've helped owners who wired up coils backwards, which doesn't work well at all. However it's marked, 15 or +, just make sure that's where White/Yellow is attached.

Bill Robertson
#5939

Well that was before the Delorean's time. I got all those coils from various NOS dealer inventories over the years and have never encountered that on a Delorean. This forum needs info as pertaining Delorean's not old Volkswagan's !
Rob

[content22207_2]

I'm a little confused why you've picked coil terminals as a red line in the sand. As stated, as long as an owner wires his coil up correctly it's all good.

FWIW: Pertronix coils only have "+" and "-", no numbers. Absent wiring changes, an owner must attach White/Yellow to + and White/Gray to -.

Bill Robertson
#5939

[PJ Grady Inc.]

I'm a little confused why you've picked coil terminals as a red line in the sand. As stated, as long as an owner wires his coil up correctly it's all good.

FWIW: Pertronix coils only have "+" and "-", no numbers. Absent wiring changes, an owner must attach White/Yellow to + and White/Gray to -.

Bill Robertson
#5939

No red line Bill...it's just a fact that the Delorean coils have + and - markings. Does being wrong on occasion threaten you? If so I'll overlook future any future errors as it's not that important to me to always be right. No one is ever always right anyway regardless of how much they think they know. It was a minor correction...not an indictment. At the end of the day we're all still humans correct?
Rob

[Farrar]

Delorean coils have + and - markings

My early '81 didn't.

[Farrar]

it's just a fact that the Delorean coils have + and - markings.

In Bill's defense, he did use the word "typically."

Now I'll step back and say to the OP that the coil you have should work fine even though it's not Bosch NOS.

[content22207_2]

I suspect the controversy isn't coils -- it's HEI. That is a modification that does not have universal agreement one way or the other. It has prompted spirited debate in the past.

For my part, I fully concede that stock ignition is fully functional. A DeLorean should be able to live its entire life running stock ignition.

But HEI's detractors need to likewise concede that it is fully functional as well. Properly installed (that's the kicker -- there are plenty of HEI installations that are not done right), a DeLorean can live its entire life running HEI as well.

Each owner needs to decide for himself whether HEI is a modification worth making. I am very happy with mine, but I can't make that decision for anyone else.

I can provide information so owners are able to make informed choices. John Hervey unfortunately does not provide complete information on his website (for example, simply replacing the Bosch coil with a Pertronix or MSD unit, absent other changes, will not increase secondary voltage, assuming the Bosch coil was healthy to begin with). Don't know if Hervey provides that information in direct communication.

Bill Robertson
#5939

[bluscreen]

Exactly.

The factory coil is fine for the stock system and stock plug gap. A so-called high voltage coil has the capability of higher voltage, but it takes a certain voltage to jump a certain plug gap and that's all there is. A hot coil by itself won't do anything at all it only takes about 15-18kV to jump the stock plug gap, and that's what will come out of the coil. So - to really get the higher voltage out of the coil, you would have to open up the spark plug gap. (If you were do this with the stock coil, you would indeed see spark failure).

Sorry to resurrect here, but this thread seemed most appropriate.

That step-up Bosch coil that Hervey sells is listed as 18k volt, which falls in your 15-18k and seems like a safe and reasonable "upgrade." Since the bump in voltage is so moderate, are there any negative consequences here? He notes it has 1.5 ohm coil resistance compared to the stock .7. Not sure what that affects...

Thanks for your input!

[Bitsyncmaster]

Sorry to resurrect here, but this thread seemed most appropriate.

That step-up Bosch coil that Hervey sells is listed as 18k volt, which falls in your 15-18k and seems like a safe and reasonable "upgrade." Since the bump in voltage is so moderate, are there any negative consequences here? He notes it has 1.5 ohm coil resistance compared to the stock .7. Not sure what that affects...

Thanks for your input!

My stock coil measured 0.387 ohms but maybe it was faulty because others have stated the stock coil is about one ohm.

If your using a 1.5 ohm coil I would think you should bypass at least one of your ignition resistors.

[David T]

My stock coil measured 0.387 ohms but maybe it was faulty because others have stated the stock coil is about one ohm.

If your using a 1.5 ohm coil I would think you should bypass at least one of your ignition resistors.

There have been more than a few instances on this forum where an owner used a non-Bosch coil and later reported early failure. It would seem if you stay with the Bosch coil it is more reliable. There doesn't seem to be any good reason to use anything else. Getting a "hotter", higher voltage coil doesn't show any measurable improvement but it does seem to decrease the reliability. For any owner looking for cheap, "bolt on" HP, there is no magic bullet. You certainly won't find it in an ignition coil. BTW, increasing the spark gap to get a "hotter" spark will increase the stress on the rest of the secondary ignition system. The cap, rotor and wires were not made for that and you can expect them to break down quickly. As for the need for a "hotter" spark, all it is for is to ignite the A/F mixture. Anything more is unnecessary. While it IS true you need a hotter spark at higher combustion pressures (like when the motor is under load during acceleration or going up a hill) the stock parts are more than enough as long as they are in good condition.