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Where To Put a Gascolator?

David Paule

Well Known Member
I've got an O-320 for my RV-3B, and as I get closer to skinning the forward cockpit area, I'm wondering where y'all have put a gascolator, assuming that you have one.

I no longer have my floor-mounted Aerolab one, as it was simply too physically painful to push that little red button in. There are other issues that I didn't care for, too. That said, it was well-made and a good conceptual approach to the issue.

I have an Andair gascolator here. It can be mounted externally to the cockpit, if I had a good place well away from the bottom of the firewall - and that restriction, all by itself, tends to negate some of its usability. I don't want to mount it on the bottom of the firewall partly due to the nearness of the exhaust pipes. A friend is welding a bracket for his to the engine mount, but for unrelated reasons that option isn't available to me. Still, if there were a good place to mount it, I would.

One thing I've been thinking of, is to make my own gascolator. I'd like to hear your thoughts about placement before I do that. If I can avoid making my own, I will.

Thank you very much,
Dave
Here's the blog.
 
The best place I can think of to put a gascolator is on the VAF classified, but that?s just me :D
 
Oh, this airplane will have one - this isn't a discussion about whether one is necessary or not. That decision has been made.

The matter at hand is which, and where.

Discussions and photos of RV-3 gascolator mountings, if anyone has any, please, along with comments of how well it worked out.

Thanks!

Dave
 
Sorry Dave, that was a snarky reply. I see an RV-3 several days a week. I will have a look next time I see it and if I can offer useful advice I will report back.
 
My -4 had it mounted at the bottom center of the firewall. Hard to imagine the -3 would be that different, but I don't know. I do know that it logically should be mounted low, and that it's a great place to collect heat and insert that heat into the fuel....

Charlie
(I still have the -4, and I still have the gascolator, but it's in a box on a shelf somewhere, now.)
 
My RV3 is nearing completion and the engine and all components are installed.
I have the O-320 and a CS prop with MT governor. Also, an angle oil filter adapter, a heat exchanger box on the firewall, baffle mounted oil cooler and Vetterman's 4 pipe exhaust.
Its important to note this because with all the other pass-throughs for wiring, hoses and such, there is very little room behind the engine on an RV3 to put much else on the firewall, due to its size. I would think you could mount the gascolater in the center of the FW, if you really plan ahead but since the motor mount is so close to the FW even that space is quickly filled with brackets and control lines for the throttle, carb, governor, spark plug harnesses, brake lines and possibly other hoses, wires, etc. I personally don't see any reason for mounting it anywhere else but the low spot in the fuel system, since that it where it is designed to go to catch and sump water in the fuel. Also, there is no low place on the FW where you can get any distance from the exhaust pipes. (Instead of a gascolator, I use an inline fuel filter on the engine side of the fuel selector valve. Although you can't drain the fuel for a visual inspection, I'm ok with that and I can easily get at it during the CI.)
Better yet, mount the gascolator first and work around it, but I would wait till you hang the engine and exhaust to drill any mounting holes.
I started by making a list of every item I planned to install on the engine and firewall and trying to establish a place for it. It is surprising the amount of things that you will need to fit in that small space.
Seems like I remember someone mounting a gascolator between the wing root and fuselage, but I'm not sure about that.
Good luck.
 
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I have one on my -4...

I have one on my -4, LWR front of firewall attached to some standoffs to keep it vertical. I have a Vetterman 4- pipe, and it sits dead center between the pipes. I made a 1/2" hole in the lower cowl that I can insert a long needled tool into and drain it. After watching a Lancair with gascolator full of water flame out and crash land right after take-off (pilot didn't get hurt), I saw the true testament of a gascolator doing its job, but in his case, it was only accessible with cowling removed.
 
On my -4 I mounted the Andair gascolator center bottom of firewall. I also built a cooling shroud for it with a blast tube. It was difficult to drain, and then the drain started leaking when fuel pump was turned on. The lowest point in my fuel system is where the tank drains are. Before I even move my plane, I stick both tanks to check for water. Gascolator now sits on bench.
 
Not the best photo, but the best I could manage with my phone, of the installation on my friend's RV-3. Looking forward toward the right portion of the lower cowl opening. Gascolator drain valve is visible just to the right of the braided stainless hose. The gascolator is on the firewall directly above. This is an early RV-3 with fuselage fuel tank only.

i-Zdm8SZ3-X2.jpg
 
Thanks, everyone!

I've decided to make my own. It will be mounted on the floor in front of the spar bulkhead, and be accessible from outside the airplane. It will have a more straight-forward, easier locking device. Like the Aerolab in some major ways, it'll be considerably simpler. In fact, it'll be homebuilt.

Dave
 
Wise move; getting it out of the cowl. But do remember that if you leave an unsealed hole in the belly (to access its drain), there's a fairly high risk of sucking exhaust gas (CO) into the cockpit. Most of the RVs (most low wing canopy'd a/c, probably) seem to have negative pressure in the cockpit.
 
Thanks, everyone!

I've decided to make my own. It will be mounted on the floor in front of the spar bulkhead, and be accessible from outside the airplane. It will have a more straight-forward, easier locking device. Like the Aerolab in some major ways, it'll be considerably simpler. In fact, it'll be homebuilt.

Dave

Looking forward to seeing details of that!
 
Wise move; getting it out of the cowl. But do remember that if you leave an unsealed hole in the belly (to access its drain), there's a fairly high risk of sucking exhaust gas (CO) into the cockpit. Most of the RVs (most low wing canopy'd a/c, probably) seem to have negative pressure in the cockpit.


Like the Aerolab, mine will be sealed to the floor.

I'd like to include a remote drain cable but haven't got that figured out yet. At this point that's a "nice to have if I can do it" feature, rather than a "must."

I won't be able to meet with a machinist friend until next week. So I've got a little time to figure this all out. Unavoidably, some parts will need to be machined.

Dave
 
Update

I designed my own and the first version was too expensive, with a lot of machining.

The second version was very simple but too heavy, at over a pound.

So the new plan is to simply use my Andair gascolator and hope that I find a decent location to attach it.

Dave
 
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