Centurion Fuel Filter

[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

[jdmcm]

Hi Malcolm

that sounds like a good plan, I will hook up the Mighty vac and catch the fuel in the canister, I was wondering about the fuel effect on the pump internals. We didn't appear to have any leaks before so hopefully we are close to a solution. I think the hose barb fitting has been installed for this very reason and if Rick's experience and ours is any indication, it is a common problem in this system. I was looking at the picture of your filter canister assembly you posted for Robin and it appears that the can on this tank is about twice as long as the one you have...but it seems to take the same filter...odd. I am going to replace the filter head in future and use a CAT fuel filter head, this will provide much better filtration, give the tank a water separator and no restriction like an inline filter may. Even though guys around here are running inline Holley filters on their performance cars right up to 8-900hp. One suggestion was an inline electric lift pump that could be switched on after protracted static periods or after maintenance. But again, I don't want to do anything to help restrict fuel flow. Even though my wallet $$$ would thank me if I could figure out a way to make this thing more fuel efficient...We honestly keep running out of fuel because of the sheer disbelief we could have consumed 100 gallons so quickly...mileage must be in the range of 6-8 gallons to the mile!

It is the first tank I have had that actually has a low and high reverse gear...and trust me...low is low...barely a walking pace. But once she is going it steers like a toy, super responsive, neutral turns, fantastic.

[Malcolm Towrie]

John, I rummaged around in the random spares we have here and found a new fuel/water separator for a Diesel engine. It makes a perfect Mityvac canister with an inlet, outlet, drain valve, and opaque bowl so you can see the level. I have attached a couple of photos. I'll mount it on the fighting compartment side of the bulkhead.

The filter head is original but there was no canister or element support hardware for it so I made a new canister from a auxiliary engine oil filter. It was heavily modified to get it to work, including shortening it. A spin on element is definitely the way to go.

6-8 mpg? That's fantastic! The manual says 1/4 mpg off road and 1/2 mpg on road so you're doing well! I did a quick calculation. Making 650 hp continuously for an hour burns 50 UK gallons. At top speed, the tank would travel 25 miles in an hour. So fuel consumption would be 1/2 mpg. So the manual numbers are based on continuous WOT operation, which is a bit unrealistic if you're just driving around a tank arena like we'll be doing.

So she's nice to drive. That's good to hear. What about the dreaded gearshifting I've heard so many bad stories about?

Malcolm

[Tony Smith]

Originally Posted by jdmcm

We honestly keep running out of fuel because of the sheer disbelief we could have consumed 100 gallons so quickly...mileage must be in the range of 6-8 gallons to the mile!

Not miles per gallon, gallons per mile. I've been told by a Cent owner that 4 Gallons to the mile is typical, ie one Jerry Can for 1.5Km, and that's premium petrol. A 205L drum (aka 44Gal or 55 US Gal) of AVGAS is the price for a 15Km burst around the paddocks. I can't complain about the CMP, positively frugal in comparison.

[jdmcm]

Malcolm that is a good setup! I am jealous of the amount of space in there with no engine installed! The gear shifting is something to get used to for sure, we don't have much space so if I can get into third I feel like I am going 100mph! Gear changes require double clutching but unlike a normal highway truck as soon as you push in the clutch and move the stick to neutral the tank instantly loses momentum and if you aren't quick you are stopping, starting in the basement and trying again. Normally you can start out on flat ground in second gear which really helps, the upshift from 1-2 i find quite difficult but 2-3 is a snap now...Tony you have burst my fuel mileage pipe dream, but what you say makes sense and explains why we are in this mess...disbelief! Perhaps I will have to start including a fuel level check on first parade!

[Malcolm Towrie]

Boy, did I misread that! Wishful thinking.

One circuit of our tank arena is about 1/4 mile and we'd normally do about 5 circuits in a show, so about a jerry can. That's not too bad. We don't have the space for an extended drive unfortunately. And the steel tracks prevent us from going off-site.

John, I've found a neat 12V pump for pre-start priming the engine with oil. Puts out about 35 psi and only draws 6 amps. I'll put it to the test when I prime the engine after installation and let you know.

Malcolm

[eddy8men]

john you are right we did clean the fuel system from the tank forward, i was conscious of the cost of a dead tank needing transport all the way to your place.
don't over think priming the fuel system, just crack a union after the filter and suck it through with a cheap plastic bulb pump (like the ones you get on an outboard)
you can't really double declutch on the way up the box, only works on the way down due to loosing speed. you need to learn to stick change. it's quite easy and you'll be super slick once it's mastered. engage clucth, move gear lever to neutral, flick any steering tiller back, engage next gear. release clutch. simples

[rob love]

There are currently 24v fuel pumps at princess auto in the surplus section for about $14.99 each. I believe they are salvaged from some larger piece of equipment, and appear to be brand new. With one of those and an inline check valve, it should be possible to set up a priming system for any 24 volt vehicle.



The pump is the same pump we used on multiple types of equipment back in my days in the military. I bought 3 or 4 for future use.



Just thought I would mention it in case it was of any use to those in Canada.