Factory Tach and Pertronix II.

[Sheriff41]

Looking more closely at the diagrams and starting to understand them better, I see that the red/green stripe wire goes to one side of a 14A fuse, #16B or16A. The other side of that fuse is the red/yellow hash #640.
My question now is; if one powers a PII with this wire as suggested and the fuse blows, (one is stuck on the side of the road if no spare available or the driver is unaware of this fuse) is there a better option wire that is NOT fused, but still a full 12V in the RUN position?
Am I making this way too complicated?

What was the final outcome, Geoff?

 

[Stanglover]

What was the final outcome, Geoff?

Nothing done yet as far as I know. I've not talked to my friend for a while, but I do know he has all the info I passed on to him. I ought to give him a call and find out. This time of year, he is busy preparing his farm machinery for spring and time to 'play' is limited.
Thanks for the reminder tough.

 

[Don C]

I would use a relay like this one from Amazon, and use the coil wire to trigger it and connect the power lead to the battery. This relay is rated for 12 volts and operates at 6 to 8 volts and won't drop out until the trigger voltage gets below 4 volts. This makes it suitable for being triggered by the reduced coil voltage and can then supply full battery voltage to the P2, without going through a fused circuit. I would still install a fuse or circuit breaker between the battery and the relay, though, in case of a short someplace. The fuse can be a higher amperage that likely won't blow unless there is a direct short. The fuse or circuit breaker will still have to be rated less than the ampacity rating than the downstream wires so that the fuse or circuit breaker pops before the wire burns up. For 14gauge automotive wiring with a temperature rating of at least 194 degrees (F) the fuse or circuit breaker can be 25 amps.
https://www.amazon.com/PACK-AMP-Waterproof-Relay-Harness/dp/B074FSZWVT/ref=sr_1_1_sspa?crid=WFC7YS5P9M00&dib=eyJ2IjoiMSJ9.6CiXZXcyMGg2s9FmvU_NFP7lcJV4SVmnrCLb1eS1FYzdbioVVRqhGJn6DUzlpUWDbxPorfC8UrpQj_8dVew3FZ6Cyz3Wd768PbnXn-2yrQllLd0uxZZLeIYE-lNsfjPViJAwdXcEEalMpxuQ3U82m_Hrhr76kWvWPeem0n-Jl8u0krkUGBMNq4TxMWQ6jAAbFAuoS3_qxmGHBMF9_Lwr-JyT3VPy5056mDdrpk2Z-y5mIwsGdXwo6EV1aJmrUaKOOqay5dDTMR18eF16uaTwGzBV5u7HHWvUcdQ9oilucM8.yWjU5pWWKO5KjWegAIJpLg7nPL6moJh7ojFQFljMxrQ&dib_tag=se&keywords=12+volt+relay&qid=1741313915&s=automotive&sprefix=12+volt+relay,automotive,496&sr=1-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

 

[Stanglover]

I would use a relay like this one from Amazon, and use the coil wire to trigger it and connect the power lead to the battery. This relay is rated for 12 volts and operates at 6 to 8 volts and won't drop out until the trigger voltage gets below 4 volts. This makes it suitable for being triggered by the reduced coil voltage and can then supply full battery voltage to the P2, without going through a fused circuit. I would still install a fuse or circuit breaker between the battery and the relay, though, in case of a short someplace. The fuse can be a higher amperage that likely won't blow unless there is a direct short. The fuse or circuit breaker will still have to be rated less than the ampacity rating than the downstream wires so that the fuse or circuit breaker pops before the wire burns up. For 14gauge automotive wiring with a temperature rating of at least 194 degrees (F) the fuse or circuit breaker can be 25 amps.
https://www.amazon.com/PACK-AMP-Waterproof-Relay-Harness/dp/B074FSZWVT/ref=sr_1_1_sspa?crid=WFC7YS5P9M00&dib=eyJ2IjoiMSJ9.6CiXZXcyMGg2s9FmvU_NFP7lcJV4SVmnrCLb1eS1FYzdbioVVRqhGJn6DUzlpUWDbxPorfC8UrpQj_8dVew3FZ6Cyz3Wd768PbnXn-2yrQllLd0uxZZLeIYE-lNsfjPViJAwdXcEEalMpxuQ3U82m_Hrhr76kWvWPeem0n-Jl8u0krkUGBMNq4TxMWQ6jAAbFAuoS3_qxmGHBMF9_Lwr-JyT3VPy5056mDdrpk2Z-y5mIwsGdXwo6EV1aJmrUaKOOqay5dDTMR18eF16uaTwGzBV5u7HHWvUcdQ9oilucM8.yWjU5pWWKO5KjWegAIJpLg7nPL6moJh7ojFQFljMxrQ&dib_tag=se&keywords=12+volt+relay&qid=1741313915&s=automotive&sprefix=12+volt+relay,automotive,496&sr=1-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

Thank you Don for that info. I'll certainly pass that on.
Looking at the Amazon link, there are several relays listed. Which one specifically were you referring to? I did not see the Pack-Amp one listed. In Canada, we often get a different listing to the US on Amazon. I would think they're pretty much the same though (hopefully!)

 

[giantpune]

Thank you Don for that info. I'll certainly pass that on.
Looking at the Amazon link, there are several relays listed. Which one specifically were you referring to? I did not see the Pack-Amp one listed. In Canada, we often get a different listing to the US on Amazon. I would think they're pretty much the same though (hopefully!)

For a pertronix, I'm using the official pertronix relay wiring kit. Theirs ship with a 30amp relay. Same type you can buy replacements for at the local auto parts store for.

If you're worried about blowing a fuse/relay and getting stranded, you may want to look into the self-resetting breakers.