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ECT and CHT on a 351 C

Posted: 2025 Oct 07, 10:32
by AcesArneson
Guys, looking for some help on which temperature sensors to use and where they should be located. I have a 351 Cleveland that I am wiring up with an EEC-V for SEFI. I have the original single lead temperature sensor in place but the ECM also needs the CHT (cylinder head temperature). Which sensor would I use and where should I put it? I am using Edelbrock Performer aluminum heads and don't see a spot for a CHT temp probe.
I have a friend with a Cleveland running on the ProM system and his has the original single wire temperature sensor on the water pump and a two wire sensor just behind it on the block. I attempted to copy this format but the only plug I have available is larger than the Crown Vic 2 wire sensor. I have a brass adapter 1/2" NPS to 1/4" NPS but I must be dealing with SAE vs. metric threads because when I went to install the sensor in the brass adapter the threads were all chewed up.
So 2 questions
1. Is this the correct location for the CHT (behind the water pump, on the block)?
2. Does anyone have an adapter that works to go from the 1/2" NPS thread to the CHT sensor thread or a 2 wire sensor that fits 1/4 NPS?

Re: ECT and CHT on a 351 C

Posted: 2025 Oct 07, 11:04
by decipha
single lead temp sensor is actually the temp 'switch' for the cluster

You dont need a CHT sensor. Simply grab an ECT sensor for a 95 GT and tap it anywhere. As long as its in direct flow of coolant its fine. Just be sure its not after the thermostat otherwise it wont read actual engine temp. Ideally youd remove the temp switch and install it there with an adapter.

Re: ECT and CHT on a 351 C

Posted: 2025 Oct 08, 03:16
by AcesArneson
Ok thanks, doesn't the single lead temp switch just run the cluster temperature gauge. (73 Mustang)
I will put the 95 GT sensor closest to the block before the thermostat.
I am assuming 2- pin ECT is pin 66 and ground? Or should it go to sensor ground in the ECM?

Re: ECT and CHT on a 351 C

Posted: 2025 Oct 08, 06:50
by decipha
sensor ground