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-   -   3 oil pressure switches? (http://www.hotrodders.com/forum/3-oil-pressure-switches-199037.html)

staleg 05-23-2011 03:00 AM

3 oil pressure switches?
 
I need 3 oil pressure switches on my Chevy small block engine.
1 for an oil pressure warning light
1 for the oil pressure gauge
1 for electric fuel pump safety cut-off.

Where Do I mount them? Speedway Motors are selling a 1/8" NPT tee fitting that fits in the oil pressure switch location above the oil filter, but what about the third one?

Jake_Dragon 05-23-2011 03:30 AM

port below the distributor is a good place.
thats where mines at

curtis73 05-23-2011 06:43 AM

You can put a tee at any one of the ports to get two holes, or just wire a relay to one switch. Just ground the fuel pump relay to the oil pressure switch so the fuel pump comes on with oil pressure and use the other post on the relay for the oil pressure light.

sqzbox 05-23-2011 06:46 AM

Should be another plug on the front of the block just behind the water pump.
I put my oil pressure gauge line there because I like to see the pressure reading from the furthest point from the pump. :D

joe_padavano 05-23-2011 09:19 AM

You don't need three switches. You can combine the oil idiot light and the fuel pump safety switch by using a Standard Motor Products PS64 sender. This sender has three terminals. The center terminal goes to the idiot light and the outer two terminals are connected together when there is oil pressure to run the fuel pump.

http://info.rockauto.com/getimage/ge...41-0&width=450

staleg 05-25-2011 02:51 PM

Thanks for the answers. Lots of good info as usual!

But maybe I don't need the oli pressure warning light, since I have the oil pressure safety switch for the fuel pump? What do you think?

To make any sence, the warning light must get on by a little higher pressure than the fuel pump safety switch will shut off the pump, right?

The safety switch I have bought will shut down the pump by an oil pressure below 7 psi.
The warning light kit i might buy have a 20 psi sending unit. Forgive me for this stupid question, but is this for warning the driver about too high oil pressure, or too low...?

The engine is a close to standard 350 small block chevy, by the way.

staleg 05-26-2011 05:59 AM

Just an update.
I found out about it. The standard "idiot lights" have an oil pressure switch that turn on the light when pressure goes below 20 psi.
The fuel pump safety swith that I already have bought, shuts down the pump when the pressure goes below 7 psi.

I will probably buy an "idiot light" kit. Those kits often have the needed tee coupler enclosed, too.

1ownerT 05-26-2011 06:46 AM

Quote:

Originally Posted by joe_padavano
You don't need three switches. You can combine the oil idiot light and the fuel pump safety switch by using a Standard Motor Products PS64 sender. This sender has three terminals. The center terminal goes to the idiot light and the outer two terminals are connected together when there is oil pressure to run the fuel pump.

http://info.rockauto.com/getimage/ge...41-0&width=450

Great tip! :thumbup:

Philbert Phlamingo 03-21-2016 11:25 AM

Better idea....
 
Quote:

Originally Posted by joe_padavano (Post 1423671)
You don't need three switches. You can combine the oil idiot light and the fuel pump safety switch by using a Standard Motor Products PS64 sender. This sender has three terminals. The center terminal goes to the idiot light and the outer two terminals are connected together when there is oil pressure to run the fuel pump.

http://info.rockauto.com/getimage/ge...41-0&width=450

The above might not be the best idea.... How about you wire the common terminal (P) of the ps64 to the fuel pump, the normally open (no oil presure) terminal to the ignition circuit and the normally closed (no oil pressure [S]) terminal to the starter circuit. The ignition will power the pump when ignition is on AND the oil pressure is present, the starter voltage/power will run the pump when the starter is engaged and the pressure is not high enough to use the ignition source via the switch. Also recommended is a relay since a starter circuit is notorious for spikes when shutting off and this would be a direct path to the pump.

This relay can also be the switching source for your oil idiot light. When the fuel pump is not getting voltage/power via the ignition you also have a low oil pressure situation. A double throw relay will throw the voltage/power not going to the pump to the oposite terminal on the relay. Use that terminal to power the low oil pressure idiot light.

joe_padavano 03-21-2016 11:33 AM

Quote:

Originally Posted by Philbert Phlamingo (Post 3606946)
The above might not be the best idea.... How about you wire the common terminal (P) of the ps64 to the fuel pump, the normally open (no oil presure) terminal to the ignition circuit and the normally closed (no oil pressure [S]) terminal to the starter circuit. The ignition will power the pump when ignition is on AND the oil pressure is present, the starter voltage/power will run the pump when the starter is engaged and the pressure is not high enough to use the ignition source via the switch. Also recommended is a relay since a starter circuit is notorious for spikes when shutting off and this would be a direct path to the pump.

Actually, I must apologize, the correct switch is PS127, not PS64. The PS127 is wired as I described (center terminal closes to ground below 4 psi oil pressure to operate the idiot light and outside terminals close to each other above 7 psi to operate the fuel pump or electric choke) and there is no internal common connections the way there are with the PS64.

Again, sorry for the bad info.

PHWOARchild 03-21-2016 04:26 PM

1 Attachment(s)
I ran the idiot light off the main tree I set up by the distributor. Just screwed a GM switch into my tee.

64nailhead 03-21-2016 06:06 PM

5 year old thread revived and Joe P. corrected himself:thumbup:

If money isn't the issue, then use one of these :

2-1/16" OIL PRESSURE, 0-100 PSI, SPORT-COMP II

It's a gauge, and idiot light (contained within the gauge), and the wiring to kill the ignition via a relay all in one. $200+ is plenty,but a lot simpler than the OP was originally looking at doing. Alot cleaner looking as well.


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