When my block was out I used a 1/8" NPT adapter with two 1/8" NPT ports so I could attach the Oil Pressure Switch, for fuel pump relay protection and a plastic hose fitting for the manual pressure gauge on my dash. The manual gauge uses a small tubing to the gauge to constantly monitor pressure, where the electrical unit uses a sometimes sketchy pressure diaphragm unit with a rubber bladder to estimate the pressure and send a signal from .05 to 5v. The problem is the electrical versions are easily subjected to ground corrosion and faulty rubber bladders on the cheapo sending units...
Getting to the rear engine block, where the modification needs to happen is nearly impossible with the engine installed, due to the proximity to the firewall and the space required to install the main adapter and then plumb and leak proof the fittings... I had to wrap teflon to build up so the angle of the fittings did not face towards the block or away from where they would actually fit without obstruction. It was several attempts to get it correct, when out of the engine bay, by wrapping enough teflon tape until it sets the angle of the ports just right... I would not want to attempt it with engine installed. There is no way to turn the wrench. It is an impossible angle to get to.
You'll need to dislocate your thumb to do it and then relocate it back after the install...
My engine came without the oil switch installed and the pressure gauge in its place. I would not recommend eliminating the pressure sending switch, as it allows the truck to run on the 1987 without a functioning fuel pump relay. Or you'll get stuck on the highway without fuel pressure... WHEN the Fuel Pump Relay fail's...
The OEM fuel pump relays did come with fly back protection from the factory, so every time they load and unload, they do not kill the alternator circuit.
Buying a quality relay, from Dephi, GM or National is very important, as the aftermarket relays are ****.
Even buying OEM quality, they still fail and you should carry a spare...
Many builders replace these OEM relays with Bosch or aftermarket cube style relays, (without flyback protection)... and then you are really in for trouble.
The stainless fitting (Second picture belowe) is what I used... it allowed me to fit the switch to the side port and use the top port for the compression fitting to the plastic hose to my manual gauge on my dash, through the firewall. The brass unit works well too.
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This fitting VVVVV (Below) eliminates the very important function of the emergency oil pressure switch and should be avoided. It is the rubber diaphragm sending unit for the electric dash gauge... it works for old school engines, and would not be advised for the 1987 model year... These are not reliable... the engine heat kills the diaphragm way too fast... they suck and will lie to you about the most important thing... actual oil pressure...
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^^^ your casting numbers are here, under the blue wires...
There may be an oil port available near your oil filter, depending on the block you have. 1987 had several different blocks, from different factories.
Some had provisions for roller cam, oil ports, manual fuel pump machining, some came without any of these features.
Unfortunately, the casting numbers are located behind the block near the firewall and most likely are not able to be seen and confirmed when the block is still in the engine bay. The 1987 year engines are so close to the firewall, and at such an incline to the frame, there is no way to even use a mirror to inspect the casting marks for engine manufacture.
I tried for months... it is not possible on many 1987 trucks to see what your casting numbers are, unless you pull the head on the driver's side or remove the engine.
Borrow a bore scope from somebody, is my only advice to confirm casting marks. Removing the hood will not help. It will just piss you off, because now you have potentially broken your windshield, in order to find out you still cannot see the casting marks... (Hood accidentally goes through windshield, without a second set of hands during removal comments, please post here
If there's a 1/8" NPT plug near your oil filter port, you are in luck... Pic from the HAMB:
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Tap for the manual gauge compression fitting here. Just make certain the feed hose for the manual oil gauge cannot get any heat from the headers or exhaust manifold. It will be very close to your pipes, in this area. Copper tubing compression is better than plastic tubing compression fittings here.
Here's a copper compression tubing oil pressure fitting at the filter location, on a BBC:
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Little to no heat on your tubing, is the best solution, either way.
Be prepared to get a face full of oil when you pull that plug and have the parts ready with teflon tape... to close it before your engine pukes in your face, or perform this install during your oil change, to avoid the mess.
Close proximity to your exhaust may mean using 45 or 90 degree fittings here, and changing direction of your plumbing fittings, to avoid heat and to enable getting a wrench on anything... the exhaust in many cases will become the limiting factor. There is simply not enough room to work, on some engine access situations. Your linkage will be in your face, as well.
