Open circuit on rotors

[rockreid]

73.5 Targa-

OK, so I've ordered the NAPA rotor with no resistor and we'll see if finally my no spark condition is resolved. I've tried everything else. My multimeter indicates an open circuit between the center pin area contact and the cap contact point on both my new PP-supplied RPM limiting rotor and the original vintage stock rotor. Both are wax potted which to me indicates they both have a resistor inside.

Really, if this indeed does resolve my situation, since I bought the MSD from here at PP they really should indicate somewhere that you need to also purchase a non-resistor rotor as well to prevent this sort of failure. This has been a good 2 months of wasted time and effort.

[wwest]

There is NEVER an electrical contact across the rotor, HV jumps just like spark gap.

[T77911S]

i have run MSD in 2 cars over the past 12 yrs and never had a BOSCH rotor go bad.

[rockreid]

wait- are you saying that from the center of the rotor to the tip should be open? There are write-ups on this forum stressing the need to remove any resistor in these rotors being used with MSD.

MSD Rotor Modification In Detail

From the center contact on the rotor to its tip I am getting open circuit. So this is normal condition?

[rockreid]

according to further research I should NOT be getting an open circuit on the rotor as measured from center contact to edge contact:

Inside a Ignition Bits


.. I should be getting some sort of resistance if my rotor's resistor is OK.

[wwest]

Originally Posted by rockreid

wait- are you saying that from the center of the rotor to the tip should be open? There are write-ups on this forum stressing the need to remove any resistor in these rotors being used with MSD.

MSD Rotor Modification In Detail

From the center contact on the rotor to its tip I am getting open circuit. So this is normal condition?

Yes, the rotor tip is not designed to make actual physical metal to metal contact with the spark plug connector post.

[911pcars]

On early 911 distributors, one could replace the rpm-limiting rotor with a solid rotor from a VW. Not sure about later distributors. Anyone ever substituted all the ignition parts (rotor, spark plugs, SP cable and end connectors) with non-resistance versions and lived to tell us about the results?

Sherwood

[T77911S]

it should not be an open but it will have high resistance.
i dont know what type of MM you are using but if you have to select the ohms scale to use and you use a low scale like 0-100, it will show an open.

i dont remember what the resistance is.