liquid_TR

I recently converted my 160FX to spark ignition. Now even though I managed to dial in the glow carb nicely with gasoline,
I want to know if I could fit in a stock EVO 26GT or MVVS 1.60 gasser walbro carb on it to benefit from the pumping action of the carb.

I'll be using 95 octane unleaded gasoline mixed with castrol 2T scooter oil (half synthetic) at 14% ratio. (about 7:1 gas/oil ratio)

It seems like I could use some readily sold parts for this conversion:

Carburetor Flange 26/35GT [EVO30941321]



Gasket, Carburetor(2) 26/35GT [EVO30941305]



Bolt, Carburetor 26GT (2)pcs. (1.6) [EVO30941307]



Nut, Carburetor(2) 26GT (1.6) [EVO30941308]



Washer(2) 25/35GT2 [EVO30941309]



Thermo-Isolation Washer, 26/35GT [EVO30941310]



Carburetor 26GT (1.6) [EVO30943224]



Will the carb flange directly fit my 160FX carb mount? the venturi, where the flange will sit, seems to be 15mm wide.

All input is welcome.

liquid_TR

BTW, here is the current setup:

Im using Bisson Pitts muffler and JXF 18x6W prop and got 8400+ steady RPM with the glow carb.

The oil ratio of this reading was an accidental 25% Amsoil. (4:1 ratio!) still ran very good - a LOT of black oil dripping from the exhaust tho

krayzc-RCU

My Feedback: (31)

[8D]

Super08

My Feedback: (2)

I like the idea. What are you getting for rpm and with what prop?

the Wasp

My Feedback: (1)

aaa you started something LOL

Jim

mrbigg

My Feedback: (21)

Nice. I always knew this engine would be nice on gas. Keep us informed.

Super08

My Feedback: (2)

Yup he did. I have switched over to flying gas only and I have a 1.60 sitting downstairs that only has about 2 gallons of glow that has gone through it. It ran great, and if it ran half as good on gas it would make a nice 26cc engine.

liquid_TR

Well then I should give you the good news,

I run the engine today again, with the new fuel mix of 7:1 (14%) with the stock carb. Dialed the needles in very nicely - they are sensitive alright but not hard to tune actually.

With a new sensor holder now the sensor is much closer to the magnet (about 1mm gap) there is virtually no missfire.

1st trial:

I guess I had the timing a little too advanced first (past 30 degrees)
It put out 8550 RPM on JXF 18x6W wood prop.
The idle was consistent if left around 2000 mark.
With 0% nitro glow fuel on glow plug the engine put out about 8600 RPM on this prop.
This concludes the engine is capable of putting out nearly the same power output with gasoline. Very impressive.

2nd trial:

I retarded the timing a little, making it easier to start and hold the idle much better around 1800-1900 rpm.
Top end was reduced to 8400-8450 rpm. Not much of a change for me to consider.
I believe the auto-advance capability of the ignition unit may have advanced the timing at higher rpms. Maybe thats why I didnt lose much rpm.

Verdict with glow carb:

The transition is just fantastic, much like an on/off switch. It howls to reach the peak rpm.
The midrange is quite perfect as well. I can hold it for minutes and it wont change rpm, it wont hesitate to go peak when I advance the throttle.
The idle is fairly consistent around 1800-1900 mark. It may flactuate here and there but will stay in this region without the mixture going rich or lean. It will advance to WOT without hesitation.
The Head temp was around 150-155 degrees Celsius at full throttle after a minute. This was checked with a fairly good quality infrared temp gun.
This indicated the engine doesnt heat up beyond dangerous region when burning gasoline fuel. It may climb a little more if less oil was used.

Problems:

There seems to be only one problem so far: the main needle. It generates air bubbles with higher throttle settings.
It is attached to the original needle valve holder, which is attached to the back plate.
This seems to be a chronic problem with the 160FX, so next time, I will attach the holder to a separate place.
The 14% oil generates a LOT of smoke. - as if a smoke system was installed on the engine. the black out spray on the test stand is much less than the previous test of accidental 25% oil.
But there is still a good amount of oil on the test stand. This may indicate I may use a bit lower oil percentage than 7:1, but since the engine is still in break in period, I will stick with 14% oil for 4 liters of gas.

Wishes:

Unfortunalely I dont have the tools or the knowledge to manufacture an adaptor flange for walbro carb, so I need to buy one ready made.
If I could adapt a walbro carb on this engine, the tuning might get easier and the idle may be more stable.
As a side benefit, the mixture would stay the same through the whole flight as the pump and regulator would take care of it, not to mention I could put the tank closer to the CG.
another wish is to use less oil in the mix as this will make it a little cleaner to run. But at the moment I dont care about the extra oil.

I will continue to put comments on the thread as I go. I will try different props on the engine with time. Also at the moment its running with Bisson pitts muffler.
I have a MVVS 160size tuned pipe (used with MVVS 1.60 gasser) but I dont have the header yet.
In about 2 weeks I will test the system with the full on tuned pipe which ought to raise the performance values a little.

So far this is all I got

rcdude7

My Feedback: (264)

Have you changed out the "O" ring seals at the needle and carb? The air bubbles you are seeing may be because the original rings may be under attack from the gasoline. Aren't the stock rings made of silicone?


Mike

liquid_TR

as a matter of fact i havent changed them. I saw these bubbles before even using gasoline - so it rules out gas-attack.
On another note, even tho gas attacks silicone orings, i believe it will take a lot of run time for them to become actually useless.

tkg

My Feedback: (1)

We run the big Super Tigers on 10% oil just fine

captinjohn

Glow fuel or gas? Ignition or glow. Some details missing! Capt,n

tkg

My Feedback: (1)

Well the thread is about Gas in a OS 160.
Sooo. We run a 10% oil mix on big Super Tigres converted to ignition and petrol.

SunShyne

My Feedback: (68)

very interesting thread idea, I too have a 160fx laying around. Would be nice if someone created a pre-made "conversion" kit for it.

nice work sir

RACJ

I have 2 OS160fx's and would love to convert to gas. Carbs seem to be the missing link. As many large 2 and 4 stroke glow engines in use looks like Walbro or someone would see this as a great market now.

Deathbunny_SG

My Feedback: (6)

If the problem was just the needle needing to be mounted on the engine then why do you need to change to a walbro carb? Why not just move the needle mount? Wouldnt there be an easer way to add a pump then switching the carb. I think the cline unit or w/e its called is basicly the pump part out of a carb? Is there other reasons the carb needs switched? I cant wait to see the numbers with a pipe, subscribed! Im building an OMP profile over the winter and it would be great to run gas in my 1.6 instead of glow on it.

captinjohn

Please try a mix with 20-1 ratio using Penzoil Air cooled lube. I do not think Amzoil good at high volumes. Use any good regular Hi perfomace oil. Thats what I am going to try. No Amzoil for me. Capt,n

gkamysz

My Feedback: (19)

The needles on a glow carb are not going to be very good for gasoline fuel. Chances are the mid range will get rich. Some carbs are worse than others. Any carb designed for high nitro will be worse in this regard.

liquid_TR

True but, this carb seems to handle it very well. The midrange seems to hold very well without getting rich. Its actually flight ready IMO. But Im waiting for the pipe.
The glow carb throat is 9.45mm or close to it. The walbro Im thinking to buy has the same throat dimensions so it seems I got it pretty close with the glow carb.

Deathbunny_SG; I got no actual reason for putting a walbro upfront as the glow carb seems to handle it really well. But I can get the proper walbro conversion parts for about 70USD. The cline regulator is about 60USD if I remember right. I'd prefer the proper walbro carb over a cline. The alternative I thought about was a perry gas pump/reg., but again I want to do a proper gas conversion for the engine, thus the walbro carb.

I will order the conversion parts today - and hopefully soon I will have a very reliable and powerful 26cc gas engine.

Rodney

You can also run into a problem on material composition. Walbro carbs usually contain some rubber or neoprene components with will decompose with alcohol. If you have any silicon parts in the engine, gasoline will attack and destroy them. The needle valves for gasoline must have a finer taper and adjustment than those used for alcohol fuel as the flow rate will be about twice as high when using alcohol instead of gasoline. If you try to use the same needle valves with gasoline as you used with alcohol you will have a hard time getting a proper fuel mixture adjustment.
I have had three Walbro carbs malfunction after using gasoline with a high alcohol content (you can not get pure gasoline in Florida any longer) so I switched to using Colman Camp Stove fuel instead. No carb problems since and power and performance seems to be the same as with gasoline although the cost per gallon is higher.

liquid_TR

Rodney, Im using pure gasoline - no kind of alcohol in it. So walbro will work fine with it. Also Ive already managed to dial in the glow carb with gasoline - its at a much leaner position than any glow Ive run yet. about 3/4 turns from closed! but it sings nicely. The silicone parts (backplate gasket, needle valve o-ring and carb mount o-ring is not in direct full time contact with gasoline. and they seem pretty tough even after an hour of run time plus a week of just sitting with gas deposit inside the engine. If I can find a suitable replacement for them, I will change them anyway. So far no problems.

I will put up a video next week on youtube if i can manage to take a recording of the engine running on gasoline with glow carb.

Jezmo

I have been using the gasoline with 10% ethanol that we have here in Texas for about three or four years now and haven't had any problems at all with my Walbro carbs. I was told that Walbro carbs are OK for use with the standard pump fuels that have some ethanol for emissions reasons. It makes sense because most states now have ethanol in their gasoline and that fuel is being used in weedwhackers, chain saws, blowers, etc. without trouble.

liquid_TR

I dropped by a couple of walbro dealers today, and it seems there is no WT-481 model sold anymore.
The guy in the shop said its quite possible to adapt another model easily for my use.

I already gave an order to advante hobby yesterday but was thinking to buy the second carb for my other 160FX locally at a better price.
Is there an alternative to the WT-481 carb that I can use with the same type of adapter flange listed above?

gkamysz

My Feedback: (19)

All of the WA, WT series use the same mounting flange. Finding the right part number can be hard. I search for mine on Ebay. I've paid as little as 4USD with shipping. I realize Ebay might not be a solution for you. There unfortunately is no cross reference for various Walbro carb models. Sometimes if you search for the one you are looking for you'll find a listing for a newer one that replaced it. The new production Walbro WA,WT series are different in that they have stops on the needles, or no main needle. It seems many newer products are not even using this series anymore. If you find a gas carb that is slighlty smaller ~9mm this should not hurt your performance on gasoline significantly.

liquid_TR

OK, here's a CDI related question. Im using the CDI ignition that I bought from Just Engines UK - its a RCexl ver2 ignition unit with plug cap for 1/4-32 spark plugs.
Here is the close up:



I soldered a thick guage wire to the tip of the exposed braided wire,
heat shrinked it all the best I can and grounded the other end to one of the bolts on the engine mount. (but at the top, the braided wire still shows it self a little.)

Here is my own setup:


The spark plug itself is this one:


I measured the resistance of the plug on both ends and found it to have no resistance. As Im new to the stuff, I presume the wire from the ignition unit have a resistance wire incorporated to it to prevent RFI.

My question is this; will this setup create unwelcome RFI to affect my servo wires or 2.4Ghz receiver?

On my trials it does affect it when the ignition wire is in very close proximity to the servo wire. (the servo immediately starts to jitter violently- look above). But will it do the same when its 20-30cm apart?

Is it beneficial to incorporate a shielded metal cap on the spark plug like the ones used with bigger spark plugs? I cant seem to find where its sold?

Basicly the 1/4-32 plug cap version of this one: