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Al
13-Mar-11, 07:43 PM
Just a quick question, I want to replace the plug caps on the Rotax 503 that I will be putting in the craft I am doing. I thought simple enough NGK plug caps x 2. I notice that NGK also do non resistor type caps for engines that use a magneto for power, apparently these give a better spark. From memory I think resistor caps helped to stop electrical interference but I may be wrong.

Should I fit resistor or non resistor plug caps?

the goose
14-Mar-11, 06:03 AM
i would fit non resistor. stronger spark providing you dont mind the tv fizzling when you start it at home.

rick

Al
14-Mar-11, 06:41 AM
i would fit non resistor. stronger spark providing you dont mind the tv fizzling when you start it at home.

rick
Cheers, have now ordered a pair.

Ewan Black
14-Mar-11, 10:58 AM
i would fit non resistor. stronger spark providing you dont mind the tv fizzling when you start it at home.

rick

An unsuppressed ignition also causes big problems for the lap timing system, if using unsuppressed caps fit resistive plugs

foster2958
14-Mar-11, 04:54 PM
Please bear in mind the following from the HCGB Construction Regulations:


"Engines shall have adequate Radio Frequency (RF) suppression fitted, as required by
common law of the United Kingdom. It should be noted that RF suppression relates
particularly to ignition systems, including spark plug leads and caps, and coils and
condensers. Suppressed plug caps are available as are low emission leads or RF
chokes for leads from most car accessory shops,

A simple check on the effectiveness of RF suppression is to turn on a transistor radio in
close proximity to the craft. If there is substantial interference then the craft RF
suppression is inadequate."

In addition to problems with the lap-scoring equipment an engine with insufficient RF suppression could play havoc with the Marshalls radios, the PA system and the video equipment.

Regards

Kevin