Got a question for the lumpers.

On my conversion (Jag xj6 with 350 TBI) i have the following:



1 Oil pressure sender ( using Jaguar original) mounted on rear of intake
manifold
I am using this sender, because it matches the Jaguar gauge and should
read accurately. Takes up space near the GM distributor, rear of manifold

2 I have another oil pressure device (oil pressure switch) also mounted in
the same area. It is a part of the F.I. fuel pump circuit. Has 12 volt
'hot at all times" and a feed back wire to the ECM B2

I am using an adapter that allows 2 oil pressure monitoring devices...


3. Here is my question,.. for those who are using a GM v8 with FI ..
"where are you installing the oil pressure switch that controls the
"idiot light"? This unit is supposed to connect to the BLk/BRN wire from
the dashboard idiot light..


Normally I would mount it near the oil filter where I can access oil pressure from the oil gallery and monitor the oil pressure - should it drop too low the idiot light comes on etc. However in this conversion there is no room in that location. I probably can concoct an arrangement of oil pressure adapters and get it all working - but under the distributor there is a lack of space and difficult to install 3 oil pressure monitoring devices. Any ideas ???



Need 1 sender for gauge
need 1 for F.I. feedback loop (fuel pump feed to ECM B2)
Need 1 for idiot light on ash


only access to oil pressure is at rear of manifold near the distributor


Thanks in advance

 

Alyn,
Not FI, but maybe it will help anyway.
My gauges and warning lights come off one triple female T fitting fed directly from the oil pressure port at the back of the manifold very near the distributor:
Everything seems to work correctly.
(';')

 

LNRB

thanks for input.. I have a set up like yours but with EFI I need to install one more "oil pressure sensing "device., and space at that location is tight.


The sensing device is needed for the ECM (EFI).
The fuel pump will not run if the EFI "oil pressure switch" is not present in the circuit. This is a special OP switch that determines if there is oil pressure and if there is,... the fuel pump will run - this is feedback to the ECM.


I guess I could omit the "idiot light" switch and use its spot to measure oil pressure for the "fuel pump running" status info that is needed on ECM B2.


What GM did (with TBI) was use the extra oil pressure port just above the oil filter boss for the oil pressure canister that enables the gauge to work
... may have to see if I can put the idiot light switch there (its smaller and may fit in that location,..or omit the idiot light feature.

 

Am glad my Fast EZ-EFI does not need that connection. I have a similar setup to Elinor's.
I would just leave out the Jaguar idiot light...

 

Roger this is a safety feature,.. if the engine loses oil pressure (engine stopped) the fuel pump will also stop pumping fuel. Good feature if involved in an accident and the engine is stopped,... the fuel pump also will stop. I would rather have this feature instead of the idiot light switch, maybe later I can find a better solution...basic problem is no room to access port above oil filter boss

 

A couple of thoughts.


1. I've thought of the oil pressure fuel pump interrupt as a safety feature and as engine protection. But, is not the inertia switch for the FP for accident safety? And as to engine protection? I think that if the lack of OP shuts down the fuel pump, it is too late.


2. As to the idiot light. Good, mebbe. Same idea if it pops and stays on, it is too late. engine damage has taken place. Flickering might be useful. Oil level low!!!!


Another lister suggested a remote block for the sensors. Engine port to block with shielded hose and AN fittings. Lind of elegant...


Hot weather is here. Cooling fans running....


Carl

 

Carl


If engine rpm is below 400 rpm, oil pressure drops and connection through the oil pressure switch...orange wire 'hot at all times" to grey wire going to ECM (engine running feedback) is lost. ( in my TBI system, if the ECM does NOT get an "engine running - oil pressure above 400 rpm" signal on B2 ...the fuel pump stops )- its designed this way.


The ECM controls the green/white "fuel pump relay" trigger wire that causes the fuel pump relay (and fuel pump) to function,..if the ECM does not get "engine running" signal on terminal B2 (from oil pressure switch) it cuts power to the Green/white wire (ECM to Fuel pump relay)- turning off relay and pump. So below 400 rpm pressure drops and switch opens causing ECM to turn off fuel pump.
That is the theory for fuel injection fuel control when rpm is below 400 rpm..or if the oil pressure switch is not present,.. the fuel pump will not run. Needs that grey feedback wire to ECM B2 to keep pump running. Tells ECM that oil pressure is being generated and engine is cranking and (above 400 rpm) sends 12V to fuel pump relay (green/white) and pump will now run...


Nice feature is: if the fuel pump relay fails and you crank the engine long enough (to get it to spin at 400rpm or above) the pump will run getting its power from the grey wire (the one going to B2 and joined to the grey fuel pump feed wire. Once engine reaches 400 rpm or above



My original post was about my concern to have 3 " oil pressure dependent switches" on the engine. Best bet for me is to get 2 switches near distributor and one from the spot over the oil filter boss - like GM did.. but not much room there with 350 in Jag body.

 

A fella I know once had an Corvaire (they were aluminum bodies) with a Chevy 327 stuffed into the back seat. Went like Stink! However, in his haste to get this car on the road, he neglected to finish connecting the fuel pump properly to the key switch, but had it on a toggle instead. He only had to remember to flip the toggle with stopping the car.

So far, so good.

Fella's friend bought the car, in this unsafe condition, but as he had been involved in creating said unsafe condition, and knew well the consequences of not flipping the toggle when shutting off the engine, all was still fine.

Enter new owner's new Girl Friend. Definitely Not a car chick.

He let her drive the car around one day while he was at work, leaving it in the parking lot when she brought it back, but didn't shut off the fuel pump.

Several hours later when he got in to start the car, it refused to turn over on the first try, so he merely tried again, as most of us would. Problem was, the engine (behind him) had a hydraulic lock on a couple cylinders, but once one of them did fire, there was a conflagration in the cabin the likes of which epic tales are told for generations.

In his panic new owner didn't even Think of shutting off the fuel pump toggle, so fresh gas was still being pumped in, feeding this fire. He only shut off the key. Only thoughts of escape at that moment.

To complicate matters, the driver door didn't work from the inside, so entrance/exit was made through the window Dukes of Hazard style. But first, he had to unbuckle the 5 point harness!

He did manage to get out with only first and second degree burns on his neck and back, and a few scrapes getting out through the window. Fire department had already been called, but the car, of course, was a total loss; only a puddle of melted aluminum with a lump of iron in the middle.

It's a Very good idea to have electric fuel pumps connected to the ignition in some fashion, to avoid such an exciting end to a classic automobile.
(';')

 

I am not against the safety aspect, just said to eliminate the idiot light and use that space for your "needed" sensor for the pump relay.

You could plug in a stainless braided hose into the plug near the oil filter and hook on your sensor and mount it remotely somewhere safe.

 

Interesting story. I used to have a 1963 Corvair Spyder convertible. Bodies are steel and they were a deathtrap with swing axle rear suspension.


If you went into a curve too fast and then chickened out by releasing the throttle (gas pedal) the car would over steer as the rear end would lift and the car would try to swap ends. Had some interesting times driving it in Montreal in winter. Not a lot of heat from it either - heat came from air circulating around the exhaust manifolds ...Ralph Nader was right Unsafe at any speed.

 

Roger that is what I am going to do ... forgo the idiot light - maybe later I can come up with something.. Basically I need 2 places to access oil pressure,.. installing a braided hose does not solve the problem.

 

Elinor:


We had one of the Mid engine Corvairs around here for a spell. A 65. 327 SBC amidship. Radiator up front. Very rough. Not aluminum.


Rust monster present, big time !!!


It would run like crazy til it got hot!!! Then smoke like a train !!


But, the headers and a really wild set of pipes sure sounded great.


Crown made elaborate kits to make the installation. Included a dummy toneau cover for the rear resembling luggage!!


And, odd. the SBC attached to the front of the Corvair transaxle. The six to the rear. So, the output shaft to the rear remained. Unless ground off as ours was !!!!


I wonder if any "healthy ones survive ?


Carl

 

Alyn:


Naaah, one of my past favorite cars was a 63 Monza with 4 on the floor. A poor man's Porsche. I drove t with aplomb and never got in trouble.


Got it just as Nader fussed about it. I have little to no respect for the guy.


Carl

 

I just looked at my SBC and there is enough room in the oil pressure sensor area for a full size OIL FILTER.. let alone another sensor???

Just looks like you need to get creative and make a proper triple tap point.

 

FOOD FOR THOUGHT:
As Roger stated, I had the same issue a you Alyn when I did the TBI conversion.
I eliminated the "OIL LIGHT" switch and installed a Oil Pressure switch wired to the B2 terminal. My future plan is to use a piece of pipe with an elbow with the correct threads and create a three port manifold. That would bring the 3 switches to the rear of the driver side cylinder head as shown in the mock-up with the red pipe in picture. I have a lot of room there. Total length of manifold will be 5 1/2 inches.
The problem is to get the pipe with the correct thread patterns. I took an old oil pressure switch to ACE hardware and they have the elbow, T fittings (for the switches and an adapter to plug the end of the pipe all made of brass. All I have to get is a piece of brass pipe, cut the pieces to the proper length. The problem with that is you have to get the pipe that is full threaded and cut the threaded pipe to the proper length, About 1 1/2 inch each. I can't find pipe with the proper thread pitch and diameter.
In the end, I don't even know whether I will like how it would look, but it is something I thought about just to get the 3rd switch operational.
Final thoughts; My gauge and fuel pump work.
It is said that when the oil light comes on it is a little too late. Do I really need to do all of that extra work??

 

Sanchez,,
Yes you understand the issue - you need oil pressure switch with B2 connection and Hot at all times on other side, all connected to f/p relay and ECM That takes one oil gallery feed.
Then you need an oil pressure feed for the gauge unit - can be Tee'd ...
together with other GM oil pressure switch.


My thinking about creating a 3 outlet pipe extension is that the weak spot is where the brass enters the block. if it accidentally gets broken off,..could be a bear to remove the stub.. just a bit too much leverage on it and you may have a problem.


I am thinking about crawling my old body under the car and see if I can get an idiot light sender switch mounted above the oil filter boss. So... did I remove the plug that is in there now when the engine was out ? Nooo.. or will I get lucky,... choose the right wrench and remove it without much trouble? Not in the real world... Maybe... Will it leak like a sieve? Maybe..
GM's solution was to use 2 oil pressure taps,.. manifold rear location and over the oil filter boss.


Did you use the GM oil pressure sender with the 3 wires (grey,.. orange and tan/white) ? (tan/white soldered to Jag wiring for for gauge )? or did you do as I did,..used the Jaguar sender and gauge. Did this because I wanted all the gauges to be the same inside the car. So Jag sender and gauge are connected with Jag tan/white wire and sender is on GM engine Tee'd

 

SAnchez



What did you do for the coolant bypass when heater is turned off ?


TBI engines have 1 coolant outlet at rear of intake manifold always circulating coolant if the engine is running. engine to heater heater to radiator amount of heat is controlled by air bleed flaps.


The Jaguar climate control actually shuts off coolant circulation using the vacuum controlled water valve.



If you route the coolant from GM350 to Jaguar water valve and then turn the heat off,..when the engine is running... the TBI engine is forced to stop circulating coolant. Where can it go? Has to go through the heater core to be able to head back to the radiator...




How did you address this?

 

SOMEBODY CORRECT ME IF I AM WRONG:

@ ALYN: Consider the GM TBI engine cooling system as 2 Circuits.
1.(PRIMARY Circuit) Hot coolant goes through the top hose, through the radiator whether it is cross flow or down flow where it is cooled by outside air and then the cooler coolant enters the engine via the bottom hose. This recirculation continues as long as the engine is running
The water pump is responsible for the coolant circulating through the top hose into the radiator and out to the engine via the bottom hose.
2. SECONDARY Circuit). The Heater core, The Bypass hose nipple located on the water pump housing and the nipple on the intake manifold and two 3/4 inch hoses.
The water pump, as it pushes the coolant through the top water hose also pushes some of the hot coolant to the heater core and out of the heater core to the nipple on the intake manifold.
Theoretically, you can block of the hoses going to and coming from the heater core and the engine will continue to cool normally using the route explained in #1 PRIMARY Circuit.
(The coolant does not have to go through the heater core to get back to the engine. The hose size is only 3/4 inch).
When you turn off the heat on the Jaguar system, you are essentially blocking the Secondary (heater core) Circuit. The PRIMARY Circuit continues to operate normally.
If it were any other way, my engine would have been toast by now. I use my AC 24/7 in Florida and I rarely see my engine temperature get up to the 90 degree mark since I did the GM swap.
On the other question, I used the Jaguar sender and gauge and the correct Temperature Sensor and adapter, purchased from Andrew. All of my gauges are OEM Jaguar.

 

Sanchez .. thanks for the explanation of your cooling system. What was throwing me off was ,..on my car I do not have a nipple on the water pump (just looked and there is a plug on the water pump) I was running my system all wrong ..with coolant going TO heater core,.. FROM rear coolant outlet on the intake manifold and then returning to the radiator. Better way to do it ,,,is as you say - water pump to heater and heater to rear outlet on intake manifold. Thanks buddy I really do appreciate your input.


There is not much room in the engine compartment and making a simpler cooling system with less hose helps a lot.
I have the beast all torn apart again as I try to tidy up the wiring and got to thinking about the coolant path and how it should be more simple than the concoction I was using. Thanks again Sanchez.. mucho appreciato lol

 

Sanchez:


Beware of hanging too many sensors and adapters off that oil port. the brass fitting is small and fragile. When I was messing with sensors, one busted with no perceptible force on my part.


Luckily in the shop and the stub came out easily!!! On the road, Can not or rather do not want to contemplate the outcome!!!


So, I have two sensors only. Idiot light and guage. Low OP cut off not in my circuitry.


So, if more sensors wanted or needed, I would go to the braided hose and remote block arrangement.


My heater is fed from two pipes off the water pump housing. But, my engine is the reverse flow LT1. Akin yet different.


Carl
.