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Re: [Healeys] Distributor to spark plug lead continuity

To: Linwood Rose <linwoodrose@mac.com>
Subject: Re: [Healeys] Distributor to spark plug lead continuity
From: Bob Spidell <bspidell@comcast.net>
Date: Thu, 21 May 2020 08:56:14 -0700
Cc: Healeys@autox.team.net
Delivered-to: mharc@autox.team.net
Delivered-to: healeys@autox.team.net
References: <337efcea-dc9a-6207-8358-60d44158a7bf@comcast.net> <3C87934D-91C9-40B6-B7CF-7C27052B2870@mac.com>
User-agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0
I should have mentioned that even your test leads will have some 
resistance, so many/most/all MMs have a 'zero' function.  If you set the 
lower ohm range and cross the leads you'll get some milliohm reading, 
then when you press the zero function the MM will display zero ohms, so 
you don't have to do the math to calculate the actual reading of your 

On 5/21/2020 8:34 AM, Linwood Rose wrote:
> Donâ??t know how distributor cap turned into radiator cap?????
> Lin
> Sent from my iPhone
>> On May 21, 2020, at 11:30 AM, Bob Spidell <bspidell@comcast.net> wrote:
>>  First, why on earth did you have a spark plug lead on a radiator 
>> cap??? (presume you meant 'distributor' cap?)
>> It looks like you have your multimeter set to diode test (maybe 
>> that's how continuity works on your MM?).* The reading is probably 
>> ohms, indicating a very low resistance circuit, but to be sure turn 
>> the MM control knob one click clockwise, to the 200 ohm range ('200 
>> omega').* It'll probably give the same reading; i.e. .792 ohms, which 
>> is about what you'd expect from a short stranded copper wire lead 
>> (IIRC, one ohm per foot of cable is considered normal, even copper 
>> has some resistance).
>> Bob
>> On 5/21/2020 7:55 AM, Linwood Rose via Healeys wrote:
>>> Hi guys,
>>> Educate me. When doing some preventative maintenance, I pulled a 
>>> spark plug lead out of the radiator cap (using a 123 distributor) 
>>> the cable pulled away from the terminal - not a particularly unusual 
>>> outcome. Got a new 90 degree terminal and crimped it on to the cable 
>>> (Pertronix cable) and before I put the boot on the end of the cable 
>>> I thought I would check the continuity. It barely dropped below 1.
>>> So then I checked a brand new, never used, cable made-up by AH 
>>> Spares. As shown in the image below when the sensors are attached to 
>>> each end of the cable I get a reading of .792 which is not 
>>> sufficient to even sound the beeper on the multimeter device. I 
>>> suppose there are degrees of continuity (not just on/off) but I 
>>> guess I expected the alarm to sound and the reading to drop to near 
>>> zero.
>>> Could someone interpret these findings for me?
>>> Thanks, as always.
>>> Lin

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