my 57 Fairlane has a Holley Sniper system, and it has a 312ci Y block motor. The temperature sensor is in the heating hose, which means I have to run the heater for the sensor to read accurately. Any suggestions for making this work without running the heater?
Upper radiator hose, just above the thermostat housing? https://www.americanvolt.com/produc...ature-adapter-electric-fan-thermostat-switch?
Moved to the off topic forum, the antiquated forum is for non automotive 1965 and older collectibles....
it needs the temp of the coolant in the engine, not the coolant that's going other places... Pictures of the engine might help, since some of us might not remember back to when we worked on a Y block last.
I drilled and tapped the intake just behind and to the drivers side of the stat. Double check for clearance inside first, it’s tight. That’s about the only place to get into the Yblock for that. There’s a bung in the head behind the distributor but I’ve never seen anything that would fit there and clear the distributor. Given the water flow in the Yblock, you really want it up at the stat housing anyway.
Holley is a one billion dollar company. Give their tech line a call! https://finance.yahoo.com/sec-filing/HLLY/0001628280-25-038097_1822928/
...because their tech guys know all about Y blocks but maybe they have encountered this before, and have a good suggestion. They also read their own forum, and answer questions there.
It’s not that I don’t respect Holley, but this was a fairly recent subject on yblocksforever. It’s been working on my old Accel unit for 14 years, and it’s Ted Eaton’s usual location for any second sending unit. If the Holley sensor is really small you might get into the little bypass hose from the stat housing to the water pump, but that’s another challenge.
You should change the sensor location. This is from the Holley Sniper instructions. COOLANT TEMPATURE SENSOR INSTALLATION Install the Coolant Temperature Sensor into a 3/8” NPT coolant passage in either the intake manifold or cylinder head. Do not overtighten or damage to the cylinder head or intake may occur. It is best to drain the some of the coolant before the sensor is installed. Use thread sealer or a small amount of thread tape. Do not install the sensor in the thermostat housing, or in an area that will not see a constant flow of coolant. Full instructions here: https://documents.holley.com/199r11031r.pdf
I have a bit of experience with temp sensor location differences. Not a Y block tho. I reckon the same logic applies. When I first put EFI onto Ol ' Furd's inline six, the only location available was the back of the block just below the head surface. I shoulda got one of those top rad hose thing-a-ma-bobs to run it there. I chase non existent t-stat problems for months. During cold months, it would never get up to proper run temp with the sensor there. That situation continued, till I found a t-stat housing with a threaded heater hose outlet, rather than the cast nipple that mine and all others I has seen had. This allowed the sensor to be located just before the t-stat. So the EFI was getting into normal run mode much quicker, and made a significant difference in short distance fuel mileage. So, I swapped over to that and just like that, I was getting proper temp readings that are so critical to the proper performance of the EFI. It's OK to put it in the heater hose connection on the outbound leg out of the crossover, or just before the t-stat. As close to the t-stat housing as possible. You want heated coolant as close to there as possible. If it is after the t-stat, the EFI will be in cold run mode until the t-stat opens. And just for information sake, there is a 20° difference in temp reading between the two locations noted above. The one on the rear of the block sees coolant temp pretty much out of the bottom of the rad after it has been cooled. During hot months, it evens out, but in cold months there is always a big difference.
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