Centurion Fuel Filter

[Robin Craig]

Malcolm can you please post a picture of as much of the fuel filter head as you can please.

I really deeply suspect there is some commonality from elsewhere.

[eddy8men]

john the ki gas puts atomized fuel through jets into the inlet manifold. pump it 3 times and press the small brass button underneath to operate when it's really cold.

[Malcolm Towrie]

Originally Posted by Robin Craig

Malcolm can you please post a picture of as much of the fuel filter head as you can please.

I really deeply suspect there is some commonality from elsewhere.

Robin, I agree. As long as the fuel filter can handle the flow of about 250 litres per hour associated with max power of 650 HP and a horribly rich AFR of about 11:1, it wil do the job.

For any Cent with the original 1/2" tubing (which is a reasonable size to supply 650 HP), it would be good if it had 1/2" tubing connections, and even better if it had the option of the male half of the original vintage UNN BSP fittings used, which had a nut and a nipple soldered to the end of the 1/2" tubing.

I'll post some photos of the filter and the fittings.
Malcolm

[jdmcm]

Thanks Rick, initially I thought that pump would be for priming the entire system but know I now better.

Malcolm my filter is also a Tecalemit, so I will track a few down. My LH fuel pump has some resistance so it feels like it will pump up, any idea how long that should take? I had the filter canister off and was hoping to have fuel beginning to drip from the filter head, but I quit before this occurred.

The manual states to start the APU and then it will fill the filters, but as we have never had the APU running yet, I was hoping for another angle to get fuel to the filters. Our Centurion only has the rear LR tank, all others have been removed. We had success before putting air to the filler on the LR tank and it seemed to push the fuel to the carbs easily, but this time the trick did not work, maybe now with a clean filter we will have success.

Perhaps the one way valves in the fuel pumps are faulty and allowing the fuel to leak back to the tank and lose it's prime. Be nice to mount a pair of spin on filters on the engine compartment firewall, primary with a water separator and a secondary to the engine

[Malcolm Towrie]

John
Since you emptied the carbs, the filter, and the line to the LR tank, it will take a while to fill the carbs again even if the pump check valves are good, I'm guessing 50 strokes?

The pumps suck fuel from the tank so you won't get any fuel flowing with the filter canister off because you have a huge vacuum leak!

I suggest installing a tee in the fuel line downstream of the filter so you can temporarily connect a handheld vacuum pump like a Mityvac to suck fuel from the tank into the filter. Or you could remove one of those nice brass knurled vent plugs from the top of the filter, drill it, and solder on a connection there.

Putting air pressure to the tank to push fuel to the filter may not be working now because there in a vent on the LR tank, that strange rhomboid shaped block sitting at the rear of the tank cover. It has small vent holes on the underside. I managed to get the tiny Allen screws out (I think I used heat) and remove the vent and found the air passage underneath completely blocked by sand and dust. When you applied air, maybe you blew a similar blockage out.

I don't think bad check valves in the fuel pumps will allow flow back into the tank because the tank outlet is it at top of the tank and the carbs can't drain and the fuel pumps are much lower so the fuel won't gravity flow to the tank.

Did you take the tank top cover off? The standpipe going down into the tank had rusted away about 6" from the bottom on ours. I soldered a new section on to get the pipe extended back down so it fitted inside the fine mesh screen at the bottom of the tank. The screen is accessed by removing the smaller cover on the underside of the tank. The bolts on the tank are all SAE, not BSF, in case you hadn't noticed!


Malcolm

[Malcolm Towrie]

Originally Posted by Robin Craig

Malcolm can you please post a picture of as much of the fuel filter head as you can please.

I really deeply suspect there is some commonality from elsewhere.

Robin,
Photo attached. Let me know if you need more.

Malcolm

20190921_194348_resized.jpg

[Robin Craig]

Malcolm that is a new beast to me. Let me digest that for a day or so.

[eddy8men]

john i also ran it dry and it was a real to get it primed again. trouble is i can't remember how we did but i'm fairly sure we cracked a pipe union before the pump and sucked it through

[jdmcm]

Thanks Gentlemen, I am going to spend some time on it this weekend. Malcolm it looks to me like someone has gone through the trouble of installing a hose barb in the fuel line then plugging it off, could this be what you were planning to do with a fitting for a vacuum pump? I will open up the tank and make sure we do not have any problems in the pickup as well.

I think I will make sure the line is clear, and I am contemplating adapting a spin on fuel filter between the tank and the pump and eliminating the old canister one entirely. As well I may bypass the aux engine for now until we get it running and running reliably.

John

[jdmcm]

Ok so had a good look at it today, removed the line from the LR tank to the hull, blew it back through with air, all clear, had a good look in tank with remote camera and flashlight and eyeballs, Rick you must have cleaned that tank because its clean! Pickup tube intact and the air flowed easy. So removed the feed line on the inlet side of the filter and blew that line back toward the tank (still unhooked so no debris blown into the tank), seems clear. I think the only problem is getting the fuel to and filling the filter. Someone has already plumbed in a union which had a hose barb attached on the line between the filter outlet and before the line splits to go to each pump. So my next move is to do as Malcolm suggested and use a might vac to draw the fuel from the tank, into the filters and then I can use the fuel pump levers to send the fuel up to the carbs...oh but first I am waiting on Canada post to deliver my filter...no domestic sources that I can find...I think replacing the filter with a spin on with locally available replacements is still on the horizon. The original filter was not in good shape and had about an inch of "mud" in the bottom of the canister.

[Malcolm Towrie]

John, I've been experimenting with the Mity-vac. We don't have the engine in yet and I redid all the tubing from the tank to the selector valve (rebuilt) to the filter (rebuilt) to the block on the bulkhead used to supply the Ki-gass hand pump. So I expected leaks. Sure enough the Mity-vac didn't pull any fuel so I hooked up one of those tools Princess's Auto sells for sucking oil out of engine sumps. It's a really neat tool. Basically it's a massive hand vacuum pump. That generated enough vacuum I could hear the leaks and fix them. Then back to the Mity-vac. Now it worked but it really doesn't like gasoline so when it sucks some in, it "delubricates" the internal rubber piston seals and gets tight to operate.

But usually with a Mity-vac, you get a little canister which acts like a catch can - you pull a vacuum on it and the fluid gets sucked into the canister and not into the Mity-vac. I'll check the canister out tomorrow and see if it works.

That hose barb you have between the filter and the fuel pumps sounds perfect for pulling a vacuum to at least fill the filter and get fuel to the pumps. It only takes around 2" Hg of vacuum to pull the fuel from the tank.

It's getting close. Should have the engine in and aligned, and the old girl driving by the end of October. I checked out the gear ratios in the transmission as the track pins are rusted up and it will take some oomph to get the tank to move initially. I definitely don't want to stress the clutch. The low reverse gear ratio is 22:1 - I've never heard of such a low gear ratio in a vehicle! (Car reverse gear ratios are usually about 4:1.) That should get her moving. There's only about 10' between the tank and the back wall but with that gear ratio, the wall shouldn't be a problem.
Malcolm