Oil PSI and Water Termp Sending Unit Sensors

[MichaelD_MK5]

I'm new to the forum so go easy.

I just received my Blueprint 347 (BP3473CTFK) engine with Sniper 2 EFI for my MKV and have the Speedhut Vintage Gauges.

I'm struggling with sending unit locations for Fan Thermo SW, Speedhut Gauge Water Temp sensor and Oil PSI sensor on the engine.

I installed the Fan Thermo SW sensor on the top of engine (pic 1).

I think the Oil PSI goes just above the Oil Filter (pic 2) but the threads are different from engine to Speedhut sensor. Speedhut states 1/8"-27 NPT for the thread size, but engine thread size is larger. Is it just a simple adapter needed?

On the Water Temp Speedhut sensor it is also 1/8"-27 NPT but where does that get located on the engine. Should it go where I installed the Fan Thermo SW sensor on top with an adapter as well and then I put the Fan Thermo SW sensor back down at the bottom of radiator? he RF harness with two green Fan Thermo SW locations is throwing me off and the one not used gets grounded.

Thank you in advance.

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[gbranham]

For oil temp sensor on my 427 SBF with ProFlo4. I bought a sandwich adaptor on Amazon for $40. Works great. For oil pressure, I bought the correct brass fitting to adapt the block to the sender. Can't remember what size it was, but I measured with thread gauges and then went to Menards to get the right bits.

I may actually have the stock hex shaft adaptor for oil pressure if you need it. You could go that route, too.I bought one and didn't use it.

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I put my water temp sender in the manifold, just before the water neck.

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[PMD24]

Details of what I did with the water temp sensors is in my build thread at post 221. But, I needed a heater connection as well. Yours will be more straightforward if you don't have a heater.

You don't need the fan thermoswitch at all. First, remove the brass plug that's in the manifold. It shows just left of the thermoswitch in your photo1. Install the EFI sensor there. My engine arrived with that already installed there by BP. It's pretty odd that it wasn't already there if they dyno'd your engine. Your EFI will then know the coolant temp. You then use the EFI to control the fan. In the Sniper2 secondary input/output harness you use the black with yellow stripe wire and connect it to the green fan thermoswitch wire in the Ron Francis harness. That allows the EFI to control the fan. The RF harness has what's called a flying lead for fan control. That's a redundant lead in the front harness where one could connect to a radiator mounted fan switch. It's not used. You can remove it from the front harness, or seal the end with adhesive lined heat shrink and leave it in the loom.

Plug that hole where you currently have the switch in the thermostat neck, using a brass plug with tapered NPT thread. Use high temp thread sealant, no teflon tape.

The oil pressure sensor supplied with the Vintage Gauges will screw directly into the hole beside the oil filter. That is a tapered pipe thread, so you may feel resistance fairly quickly. Just make sure it's not cross threaded and tighten it. Use high temp thread sealant, no teflon tape.

Note: This is my first build so if any of the experts here, especially those who have done several builds, disagree with any of my directions above, please weigh in. Thanks.

Pat

[Papa]

Get one of these:

Check out this page from Summit Racing https://www.summitracing.com/parts/sdk-c2oz-9b339-c

You'll also need a reducer bushing to adapt the 1/4" to 1/8" sensor threads.

[gbranham]

That Scott Drake piece Papa references is the one I bought but never used. If anyone needs it, let me know. Free to a good home.

Greg

[MichaelD_MK5]

Ok, post 221 was helpful. In my case, BP already had the EFI CTS sensor installed on the driver side manifold behind distributor cap with the black/green wire (so it wasn't missing). I'll cap the two RF harness Fan Thermo SW wires at front and top by engine with heat shrink and let Sniper 2 do its thing with fan control. For the Water Temp gauge, I removed my previous install of the fan thermo sensor that came from FF kit and will put the Water Temp sensor from the Speedhut gauge (white/black wires) similar to what PMD24 did in his coolant ports2 lr.jpg pic in the thermostat housing. Needed an adapter from Summit for that. I also ordered the Papa suggested extension for the Oil PSI port and some other brass adapters from Summit so will see next week what works on 347. That gives me Sniper coolant temp from manifold, gauge water temp from t-stat housing and oil psi just above oil filter location. Thanks everyone!

[PMD24]

Here's a photo of mine. This is on a BP347 with Holley Sniper2. In my opinion the extender is not required. But like Papa says, you will need the adapter. The sender that came with the gauges should have the adapter on it so it will fit right in. Mine came that way. If not it's just a standard brass pipe adapter that you can buy at Home Depot or Lowes. In my opinion you cap only the thermo switch wire in the front harness near the radiator. The other one you refer to is where you connect the black/yellow wire from the Holley I/O subharness. That's the output for the EFI to control the fan.

PM me if you don't have the Holley harness one page schematic and I can email it to you.

If you don't have a heater you can use the two manifold ports for your two water temps (EFI and Gauge). That way you can stay awy from using the one on the t-stat neck. That's less than ideal because it's on the downstream side of the stat so you won't see the correct temp on you gauge until the stat opens.

Pat

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