Cannot safely fit late model carburetor into Ranger 29

[OfficeMonkey]

Hi folks -

My engine now has a few Issues, and I have a mechanic scheduled to come take a look. However, there's a fundamental problem:
The oil pressure sender mounted towards the fore is forced out of the way by the (new) late model carburetor+adapter+flame arrestor.

This causes two specific problems.
1. Engine wouldn't start because the oil pressure sender shorted through the flame arrestor->carburetor->engine. I have temporarily "installed" a piece of electrical tape to prevent the short, but can't imagine this is by design -- or safe.
2. The minor adjustment I had to make to the mounting of the oil pressure sender to install the flame arrestor has resulted in an oil leak feeding from the engine into the oil pressure sender.

I do not believe the horizontally mounted flame arrestor would remotely fit in this opening either, but don't have the dimensions to prove it.

Was there some installation secret I missed? Am I just out of luck?

Images attached.

[ndutton]

Oil pressure sender shorting through the flame arrester - I don't see how this is possible. Everything about the oil pressure sender is grounds and the flame arrester is grounded so what can short? Even if the wire that attaches to the sender touches ground all that happens is the gauge needle pegs high.

As for no room for the sender, relocate it to a bulkhead anywhere you want with a short piece of 300PSI oil rated hose. Be sure to include a ground wire to the case of the sender or it will not work. Include the oil pressure safety switch I see in the picture with the sender relocation.

[JOHN COOKSON]

The device in the picture looks like an OPSS. The wire closest to the back flame arrestor goes to a fuel pump? The other wire on the device is connected to the + terminal on the coil?
When you start the engine the oil pressure rises and the OPSS closes* and the wire from the coil is now grounded to the back flame arrestor which results in a shut down.
Can you move the OPSS out on a nipple or as suggested to a bulkhead?
* The OPSS is a normal open switch

ex TRUE GRIT

[OfficeMonkey]

The device in the picture looks like an OPSS. The wire closest to the back flame arrestor goes to a fuel pump? The other wire on the device is connected to the + terminal on the coil?
When you start the engine the oil pressure rises and the OPSS closes* and the wire from the coil is now grounded to the back flame arrestor which results in a shut down.

ex TRUE GRIT

The side furthest from the flame arrestor goes to the fuel pump; I believe that makes the side closer to the flame arrestor +, with the oil pressure sensor only activating if pressure is high enough. Until I separated them with tape, the starter motor wouldn't kick in -- the solenoid clicked, but then the entire boat shorted.

Can you move the OPSS out on a nipple or as suggested to a bulkhead?
* The OPSS is a normal open switch

ex TRUE GRIT

It's rather tight quarters. I'm pretty sure I can remove the OPSS (drain oil, unscrew, etc.), but I can't imagine having enough bulkhead space to mount it elsewhere. Putting some sort of extension wouldn't really work -- and I don't even really need an extension, I just need to rotate it ~15 degrees. Is there any way to reposition it?

[JOHN COOKSON]

YES!

Hi
Was there some installation secret I missed?
.

The hot lead to the OPSS should be fuse protected rather than insulated by a piece of tape.
You are risking melted wiring and possibly starting a fire.

ex TRUE GRIT

[OfficeMonkey]

The hot lead to the OPSS should be fuse protected rather than insulated by a piece of tape.
You are risking melted wiring and possibly starting a fire.

ex TRUE GRIT

Agreed and understood. I'll insert a fuse into the wire.

[Marian Claire]

My oil pressure gauge is mechanical so I do not have the bulky sender. There are pics in the online parts that show the "proper" set up and there is plenty of room between the OPSS and Flame arrestor. As you say just turning, counterclockwise, should separate the terminal from the flame arrestor but that would be loosening the whole setup and could cause a oil leak and if it is loose it could flop back down and cause the same problem or worse. You may just have to rebuild it properly. Easier said than done.

Dan
S/V Marian Claire

[Peter]

Late model engines have a second oil pressure port near the oil pressure adjustment that an OPSS can be installed in. Does the early model engine not have that port?

Peter

[OfficeMonkey]

My oil pressure gauge is mechanical so I do not have the bulky sender. There are pics in the online parts that show the "proper" set up and there is plenty of room between the OPSS and Flame arrestor. As you say just turning, counterclockwise, should separate the terminal from the flame arrestor but that would be loosening the whole setup and could cause a oil leak and if it is loose it could flop back down and cause the same problem or worse. You may just have to rebuild it properly. Easier said than done.

Dan
S/V Marian Claire

It definitely caused a leak. =] I'll look for the pictures of the proper setup and see if I can remove and adjust -- I discovered that I need to change the oil anyway, so...

Late model engines have a second oil pressure port near the oil pressure adjustment that an OPSS can be installed in. Does the early model engine not have that port?

Peter

I don't think I have one, sadly. Where there would be one on my engine I believe there is a mounting bracket for the throttle cable. I am, however, going to go down and double check later today.

[Marian Claire]

I dug in my spare parts and it seems to me that the addition of the adapter would push the flame arrestor forward almost 1/2". The total length of a late model flame arrestor frame is about 4 1/4" and slides directly on the carb about a 1/2". I am not on the boat so I can not measure the length of the early frame assembly. How much room do you have from the forward end of the carb to the terminal on the OPSS? If it is more than 3 3/4" then maybe a late model frame would work after removing the adapter. ???

Dan
S/V Marian Claire

[Marian Claire]

Late model engines have a second oil pressure port near the oil pressure adjustment that an OPSS can be installed in. Does the early model engine not have that port?

Peter

I believe the early block does have a port just above the oil pressure adjustment.

Dan
S/V Marian Claire

[OfficeMonkey]

I dug in my spare parts and it seems to me that the addition of the adapter would push the flame arrestor forward almost 1/2". The total length of a late model flame arrestor frame is about 4 1/4" and slides directly on the carb about a 1/2". I am not on the boat so I can not measure the length of the early frame assembly. How much room do you have from the forward end of the carb to the terminal on the OPSS? If it is more than 3 3/4" then maybe a late model frame would work after removing the adapter. ???

Dan
S/V Marian Claire

I went in with a tape measure. Admittedly, the angle is not great, but I think my gap is closer to 3" -- measured all the way to the root of the caburetor.

I believe the early block does have a port just above the oil pressure adjustment.

Dan
S/V Marian Claire

I found a... thing! I'm not sure whether this is the port; immediately aft of the fuel pump, there is a large nut (it appears to be the circled point in the thread on changing the oil pressure . It looks like the head of a bolt. Picture attached, but it looks like it matches the location in this thread.

Based on dimensions, I think my best plan of action:
1. Not start the engine any time soon.
2. Get 90 degree brass elbow (dimensions to be determined).
3. Drain oil.
4. Relocate oil pressure sending unit to oil pressure port aft of fuel pump.
5. Reattach oil pressure alarm to existing fore oil pressure port.
6. Reconnect oil pressure sending unit -- putting a fuse inline before activating.
7. Refill oil.

[OfficeMonkey]

Inserting missed photos.

[Marian Claire]

Thanks for the info. I figured the space was going to be to small.
The nut in your pic is the locking nut for the oil pressure adjustment. The nut has to be loosened and then the threaded part turned in to increase pressure or out to decrease pressure using the slot in the end of the threaded part. The port is the smaller plug with a slot in your pic. The Moyer 360 shows the OPSS installed above the oil pressure adjustment.

https://www.moyermarine.com/mmi360/r2z1.html

You can see the early style pressure adjustment assembly at the bottom of the page here.

https://moyermarine.com/product-category/oilsystem/

Dan
S/V Marian Claire

[JOHN COOKSON]

If you want to start the engine before the repairs\modifications are completed take the the two wires off the OPSS, hook them together, and temporally wrap the connection with tape. This will bypass the OPSS.

ex TRUE GRIT