Pro

Has anyone ran into this or have any ideas? Do the thirdgen TBIs have this (for those that go from TBI to TPI as well)?
This is a 1995 350 TBI motor, and I am just trying to test fit a TPI manifold on today. I cant think of any way around it unless anyone has any ideas.

Abubaca

iTrader: (3)

My 89 TPI car did NOT have that. I know because I removed the plug that was there, and added a sender! ...that one you've got is pretty darn TALL!!!!!!! ....I'm running a 90* fitting that is about HALF that tall. From there, you can plumb it any way you like.

Abubaca

iTrader: (3)

Looks like this.

Abubaca

iTrader: (3)

TPI cars use the port right above the oil filter, so if that's available, that's an option too. Not sure what that motor might have there. I added a transducer so my Holley EFI would read pressure. The block I'm using has a plug in the port above the filter, and it was SOOOO darn tight....I left it alone and used that port on the china wall.

Pro

Do you have a link to purchase one of these fittings? Ill give it a shot and hopefully it will allow the manifold to clear.

I assume the one I have is stock. This guy has the same:

Pro

I took out the tall one and put the manifold back down and have about a 1.5 inch area to work with.
I have no idea why GM made them so tall for the trucks. And possibly TBI F-bodys

Abubaca

iTrader: (3)

You can see how much taller that one is compared to the one I posted.

I don't have the proper male size off the top of my head, and even if I remembered the female size, I can't be sure that's the same size as what GM uses. You'll have to measure. I'd take the sender to the hardware store and check the plumbing isle. Even if you can't find the exact fitting you need, you can find your sizes. Then jump online and order one up.

Pro

I checked out home depot. They are pipe fitting sizes. In the block is 1/8 and to the sensor is 1/4.
While there I checked out what they had. They didnt have any elbows that were 1/8 male 1/4 female, so I picked up this instead, but this might be asking for leaks.

GeneralDisorder

iTrader: (1)

TPI Corvette models have the oil pressure sensor in the back like that. You might see if you find the part number for a TPI C4 Vette. Like 1990 or so.

You don't want to move it to the stock F body location instead?

If you do use that bunch of adaptors get some Loctite 545. It won't leak.

GD

Pro

Where is it on the F body? I read somewhere it changed, in 89 from behind the block to above the oil filter?
But even if I do move it, I would have to find a way to plug this hole, rewire, and swap sensor harnesses (assuming the sensors are different).

GeneralDisorder

iTrader: (1)

Yes it moved to above the filter. The early ones were behind the manifold. Above the filter makes the sensor much more accessible. Lengthening the wire isn't a big deal.

Stock china wall mount has the sensor 45 degree angled to the drivers side so you can remove it without pulling the disty and doing the Gumby impersonation.

If you have a lathe you could easily shorten the truck adaptor..... still putting it above the oil filter would be my preference.

GD

Pro

Ok thanks for the info.

NoEmissions84TA

iTrader: (1)

That brass GM piece has a very heavy wall thickness, compared to the HD plumbing parts.
I once had an engine I had to do the same to, and the nipple broke off, and the engine pumped
a good amount of oil out before I discovered no oil pressure on my gauge. But my nipple was
something like 2.5" long. You can probably get away with doing this because that nipple is so short.

Also be sure to use the correct intake manifold gaskets to match the intake you plan to use.
Notice the rear coolant crossover ports.

Pro

Thanks yes I haven't swapped out the old tbi gaskets yet.
Here is underneath the truck. I assume this is the port you guys are referring to (about the sensor location?).
BTW, wouldn't it great really-really hot right next to the header/manifold and possibly a reason why GM didn't put it there in the first place? At least for the trucks.

NoEmissions84TA

iTrader: (1)

That oil port is located here (red arrow). It will be either a recessed square or hex 1/4" NPT plug. And it will not come out easily. For square, if you don't have the proper bit, you can make your own square drive L shaped wrench (like an Allen wrench - only square) by buying some key stock. Cut it to length, heat with a torch and bend.

Pro

I'm going to try this first. The fitting seems to clear and held good pressure on my air compressor but ill watch it and see how it does on liquid when i get the motor started, hopefully this month.
And apparently the programming on the trucks use this sensor to also shut the motor down if the pressure gets too low. Or maybe its like that on all TBI.

jharrison5

Ran into this same issue with the '98 vortec i dropped in. I had my father in law turn it down and re-thread it and it fit perfectly. It's post #30 in my build thread if you want to see some pics of the final product.

https://www.thirdgen.org/forums/memb...ml#post6027146

Pro

Nice. Its always something. With the manifold in place (kinda) my new thing is the coil and bracket now smack into the transmission dipstick.

Fred SS

iTrader: (3)

When I did my TPI conversion a few years ago on my 87 Monte Carlo SS, I used a OEM GM oil pressure adapter that goes at the rear of the block. I googled tpi corvette oil pressure switch adapter or something like that and found the correct fitting. The stock piece has a special 90 degree steel fitting that screws into the block. Then another fitting that is hex shaped screws into the 90 degree fitting. The hex fitting has two ports on it, which worked out great for me. I have the stock TPI fuel pump backup oil pressure switch mounted to the hex adapter along with the original Monte oil pressure switch. I have the oil pressure sender mounted in the normal location, above the oil filter. If I can find a picture of the fittings, I'll post them up.

Fast355

iTrader: (2)

I ran into the same issue with my old G-van. I ended up using a LT1 Caprice cop car oil sending unit with a 1/8" npt fitting and a 1/8" brass elbow. I had to use the Caprice one because it had both the fuel pump pressure switch and 80 psi sending unit. I had to install the fitting and have it tight prior to installing the intake.

Fast355

iTrader: (2)

This was my coil mounting bracket fix.

Pro

I think this may work. I just reused intake bolts that the TBI had. The ones that have a built-in nut on it, so you can mount a riser plate, I thought for the MAP sensor. So in this case it would be for the coil.

I also put the truck EGR solenoid on there, sidewide, luckly they both had holes that lined up nicely and barely fit behind the fuel rail when tilted, and now the harness doesnt have to be stretched and rewired. Unfortunately the EGR is required for another 3 years in this state on this truck

BTW, I torqued the intake down at 35 lbs, hopefully that was enough. I see numbers all over the place on the internet. One guy said his GM manual said 20-45 was good enough

Anyway the thread was originally about an oil sensor lol and i think thats fixed but well see when i start it up later. And if the fitting leaks, cant hold the pressure, for whatever reason, maybe ill just move it down to the filter.

Pro

Don't do the home depot special I did.
After a total of about an hour of driving I've lost about a quart of oil. I haven't put a mirror back there yet but I doubt its over the china wall. Its wet all over the sensor and the thing that I made.
I happen to have an LT1 elbow lying around. And it looks like the TBI and LT1 sensors use the same connectors. So if the LT1 screws in the wall, and a new sensor hooks up with no problem, then I'm down with that.

Drew

iTrader: (58)

Assume there's a good reason you don't want to move the sender to the port above the oil filter?

Pro

1 less thing that's not currently leaking that if I took apart could start.
If the LT1 elbow doesn't clear then ill do that.
What did GM use to block off that port on the wall when they moved the sensor to above the filter?

Drew

iTrader: (58)

Square drive pipe plug. IIRC. Any pipe thread plug should work fine. Little bit of teflon thread sealer on the threads, turn in until it snugs up, just a hair further and good to go.

Bob88GTA

iTrader: (2)

Just an 1/8" plug. Coat the threads with teflon tape or LocTite 545

Pro

It looks like the trucks get a 14 inch plug.
But the ***-end of the sensor would come really close to the header.

Drew

iTrader: (58)

Well, that only leaves one option... Time to put it in a thirdgen. Kidding.

Pro

ha yea right
what's the NPT size on the one above the filter?
I ordered from amazon the 1/4.... but now that I want to move to down below, the thirdgens look like they are 1/8.