Lotus Elan

Side entry distributor cap cannot use carbon core wires

PostPost by: billmoore42 » Sat Jul 31, 2021 11:17 pm

I have been having trouble with my 67 FHC as far as occasionally losing a cylinder, rough running, hard starting, etc. It has also been occasionally fouling plugs.

Typically, I replaced the plugs and checked the distributor cap after a bad running episode and found one of the carbon cored spark plug lead wires almost falling out of the cap. Cutting off a bit of the wire and reinstalling has typically solved this problem.

However, I just read on the MGB forum that side entry caps require copper cored wires, as the grub screws in the side entry cap do not make good contact with the carbon core of the wire.

This seems to make a great deal of sense and will solve a lot of my problems as far as rough running on occasion. Can anyone second this revelation before I go out and buy new leads?

Thanks
1967 Lotus Elan FHC Spyder Chassis
1972 MGB (since 1975)
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PostPost by: bitsobrits » Sat Jul 31, 2021 11:43 pm

I had troubles with carbon core as well, but have changed to spiral wound suppressor type (Magnacore and similar) wires without issue.
Steve

Elan S1 1963-Bourne bodied
Elan S3 1967 FHC pre airflow

Formerly:
Elan S1 1964
Elan S3 1966 FHC pre airflow
Elan S3 1967 FHC airflow
Elan S4 1969 FHC
Europa S2 1970
Esprit S2 1979
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PostPost by: UAB807F » Sun Aug 01, 2021 5:55 am

I run copper core with suppressed caps on my car but did briefly try carbon core wires. IIRC they came with a thin metal wire inserted in the cap end, running into the carbon core, out the back & bent over to run forward in a U shape profile. I assumed this was a mod to give a good contact point for the screw.

I don't know if that's a long term solution, I only ran them for a short while but while I had them there were no problems like you describe.

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PostPost by: Andy8421 » Sun Aug 01, 2021 6:32 am

UAB807F wrote:I run copper core with suppressed caps on my car but did briefly try carbon core wires. IIRC they came with a thin metal wire inserted in the cap end, running into the carbon core, out the back & bent over to run forward in a U shape profile. I assumed this was a mod to give a good contact point for the screw.

I don't know if that's a long term solution, I only ran them for a short while but while I had them there were no problems like you describe.

Brian

I have never been a fan of carbon string leads, having had to replace many sets over the years because of internal breakdown. Having the suppression 'lumped' near the source of the interference (the plug) seems a much better design. Copper cored leads and either suppressed caps or resistor plugs would be my suggestion. NGK make a nice suppressed cap with good quality seals on the plug entry and cable entry points.

In response to the OP, I have also seen carbon leads with a length of wire inserted and bent over - but usually to make connection with brass crimped connectors, not to use with dizzy caps with cable piercing screws. There are comments on the MG forum that bending a short length of wire into a 'U' and inserting both arms into the carbon core gives a cable piercing screw something to make contact with, but I would show your existing leads the bin and go with copper / lumped suppression were I you.

Good luck.

Edit: These are the caps I use:

https://www.gsparkplug.com/1x-ngk-resistor-spark-plug-cap-sb05f-red-8567.html?gclid=EAIaIQobChMIvK6bp5qP8gIVyMLtCh1EkQBTEAQYASABEgJwkPD_BwE
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PostPost by: UAB807F » Sun Aug 01, 2021 7:19 am

Andy8421 wrote:I have never been a fan of carbon string leads, having had to replace many sets over the years because of internal breakdown. Having the suppression 'lumped' near the source of the interference (the plug) seems a much better design. Copper cored leads and either suppressed caps or resistor plugs would be my suggestion. NGK make a nice suppressed cap with good quality seals on the plug entry and cable entry points.

Edit: These are the caps I use:

https://www.gsparkplug.com/1x-ngk-resistor-spark-plug-cap-sb05f-red-8567.html?gclid=EAIaIQobChMIvK6bp5qP8gIVyMLtCh1EkQBTEAQYASABEgJwkPD_BwE


:) Exactly the same thoughts I had, including the choice of plug cap & supplier ! (although mine are the angled ones)

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PostPost by: billmoore42 » Sun Aug 01, 2021 2:36 pm

Thanks everyone:

I am dumping my existing leads and going with copper cores and NGK BPR6ES plugs.
1967 Lotus Elan FHC Spyder Chassis
1972 MGB (since 1975)
billmoore42
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PostPost by: billmoore42 » Sat Aug 21, 2021 10:04 pm

In conclusion, I bought Magnecor wires part 4790 for the Elan. Pretty expensive at around $126.00 delivered, but I figure they will not be the part that leaves me stranded on the side of the road.

I also installed NGK 7311 BP6HS non resistor spark plugs, figuring the lower resistance of this plug would provide more juice to the plugs, and help prevent fouling in my mixed urban stop and start driving, which can include unexpected traffic jams and their longer idle times.

The car seems to idle smoother now, without any surging. My new model Pioneer stereo with AM radio has no increase in static, and AM comes in just fine.

So, so far, happy!
1967 Lotus Elan FHC Spyder Chassis
1972 MGB (since 1975)
billmoore42
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Posts: 55
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