Cap, should my fuel turn cloudy when I mix the Gas / glow?

I can't recall mine ever did but I didn't mix it in a clear container.

What you really need to look for is seperation.

I was playing with Opti-2 and glow fuel and gas and it didn't mix.
There was thousands of little oil balls and shaking or stirring did nothing for it.

It did make a good weed killer though.

I do not know...I did not see that happen with my mix. What did you mix up exactly? Capt,n

I did the 1 part / 2 part mix using what I could find. Traxxas Top Fuel 10% and gas. If compression ratio is my problem then that is easy enough to fix. I would have to special order the S T fuel or drive 120 miles round trip to find it in Sacramento. My local hobby shop just closed in December. If I just don't get in a hurry then I can get S T fuel next month when I have to go through Sac. on my way to Reno if I-80 is clear.

For my first sucessful runs i actually used some 20% nitro/ 12% oil car/truck fuel and it worked fine, once again didn't notice it was cloudy, mixed in a varsol white gallon jug, couldn't see in, looked fine in the tank though.

Got it to run on 50-50. Also rechecked the head, .060, I would have to guess that I didn't change this engine. It's been a while. Used an OS#8, a four stroke would not work. Only threw the prop when I leaned it out too far working on the low end. Do these symptoms suggest something other than that I don't have a clue.

Did it run and any RPM above a idle? Leave glow on untill the engine is fullly warmed up. You need a muffler on it to retain glow-plug heat at idle. What do you mean by 50-50 mix? I need more data so I or anyone else can zero in on what amy cause the way it runs. Thanks Capt,n P.S. is this the 25cc Homelite or ???

I used a muffler and it was warm. Could not get it to run on both needles. There was a low end needle position where it was obvious that it liked. Top end was a different situation all together. I tried to adjust the needles as suggested on sites dedicated to the Walbro. 50% gas - 50% glow

If the engine acted like it was going lean on top end...you may have to bend the little tab on the inlet control valve this has a needle valve which controls fuel into carb. I think raising the tab up allows more fuel in. Measure the position first with a strait edge. Bend very little...may .010 at a time. There is more on this in the Gas/glow postings. Good Luck Capt,n

The other thing is that a 50/50 mix will be leaner mix than a 33/66 mix.

It will take more fuel at 50/50 because of the extra alcohol .

Very good catch Ralph...what you say about the more alcohol in 50/50 mix. Now if the right amount of gas was added....the mix may work. I Think. Capt,n

The breaking point seems to be close to 1/3 Alcohol.
Less than this and you need constant heat on the glow plug.
But the carbs. seem to be able to meter the fuel.
More than this and you may run into lean conditions.

I would venture to say that a glow style carb. would be better than a gas carb.
at the 50/50 ratio .

Because of the metering Capabilities.

I had asked eariler, maybe on a different thread, if anyone had tried a 50/50 raito on a glow engine.

Perhaps some 20/20 and a little oil added for the bushings.

I got no responce.

I questioned the wisdom of the 50/50 and expected to work back down to close to 33/66. I have a muffler that is a little more open and will try that. As far as using an R/C carb, I have, a ST 51 with muffler pressure on gas only and spark it seemed to run as well as the Walbro. When I pulled the fuel line off of the carb while the engine was running I got quite a stream of fuel so muffler pressure seems to work. I would believe either carb would work. It may be a week or so before I can try again. Thanks for the imput, everyone around here is plug and play and can't think outside the box.

This is because the carb. is set up for glow fuel. The carb. can meter more fuel than a gas carb of the same size.
There are internal adjustments that can be made to the Walbro carb that will help it meter more fuel.

You have a ST-51 on EI?

The alcohol is what keeps the glow fuel lit.
With spark I would think that a 50/50 mix should work and would be easier to adjust the carb. with than a 33/66 mix.

So what is the engine doing or not doing?

You might want to reconsider using muffler pressure on gasoline. Gas exhaust is hotter than glow fuel exhaust; gas is far more volitile than methanol/oil fuel. If it were me, I would not route hot exhaust to a gas fuel tank. You could make a memorable event. []

You might try a pressure tap in crankcase and use crankcase pressure. You will probably need a one way "check " valve in pressure line. Also a pump that works off vibes of engine works too. Then there is the cline regulator pump. If you handy...use just the pumping section of a Walbro carb. Now someone is going to say...just use a complete Walbro crab. The only thing they are big and ugly....besides....if you want to do ever thing the easy way...forget conversions, and buy a Ready to go engine!!!!!! I may do that some day. Capt,n

You have given me a lot to consider. First as to muffler pressure and gas. This test was just that, a test. I am concerned about muffler pressure and gas. I purchased a Perry pump that runs on crankcase pressure. This pump could be used for fuel or smoke. There was too much pressure. I thought about the oscillating pump but have not gotten to that yet.
As for the ST-51 carb. I have run that carb on a 25cc weedeater with an adapter made of .500 aluminum. This is what I used muffler pressure on. The ST has a sharp point on the hi end needle, just one "click" on the hi needle would make quite a difference. The low needle was not a problem and the engine responded very well. This engine had the "TIM" ignition (SAM). The ST carb is, I believe, the same as on the 61 or even bigger. (Tower info on carbs.) BTW the tim units require "dwell", so 3 .250 magnets all south in a row at 1.3" diameter. The ability of the ST to supply plenty of gas is why I took it off my ST. It is now back on the 51 with gas and CH ignition. 20% synthetic oil to 80% gas. Idle has been a little of a problem so I put the Syncro spark on it. I have not had time to try it again. Turned 11.6 on an APC 10/7. If it looks like I am going in too many directions at one time, I am! Also, the 20% oil to 80% gas was the result of an e-mail to an engine expert at an R/C magazine who's opinion I respect.

I'd sure like to see a picture of that ST-51 on EI.

The numbers on it seem reasonable.

Not as good as glow but very usable.

ST 51 #$^%&*&%$$# Computer problem!!!!

Second try, My ST 51. The engine was modified for another purpose. STOCK out of the box + gas and go. An Evolution and the ST.

Found this in the wife's computer. The evolution is on mag ignition 31 oz.

Got the gas/glow WORKING. The top end cleaded up but the idle is another problem. The butterfly in the carb does NOT have a notch cut in it at the idle outlet. I have had this problem in other carbs so I filed a notch. The idle improved quite a bit. I will try this on my G/G engine.
Changes to the 25cc;
1- cut .030 off the bottom of the cylinder, There is about .030 at the top (by the solder measurment).
2- Used a modified stock muffler with two 3/8 od pipes with the innerds removed.
3- used the 33/66 mix. The fuel looks like it is trying to seperate.
4- OS #8 plug
Back to the carb. I opened a single needle carb for another (2 bolt) Weedeater 25cc. It is now .350 +-. It would not idle low enough to fly so I filed the above mentioned notch in the brass butterfly and got an idle. This engine has had the cylinder cut on it and has about .025 on top. With muffler it turned my 16/8 APC at 7700 rpm using the intake manifold with the rear facing carb. The muffler is home made from 1/8" aluminum and the bottom of a seamless soup can. It gets laughs but at 2 oz +- I don't care. You can braze the steel can. The 16/8 APC is the base line prop for all my engines, no special reason, I just had it when I started.

Check this picture!

What's going on with that mutant engine! I can see a plug cap, some strangely angled fasteners around the back and a carb set at a jaunty angle. Please explain - with more piccys [8D]

I've been doing Gas/Glow for quite a while, and I've never had fuel separate like that. Try a different brand of gasoline.

Gasoline that has water in it will do this too. The water combines with the alcohol in the glow fuel and separates out.

AV8TOR

This is a reply to the last two posts. GOT GAS? My first run today was VERY PROMISING. Made change to carb, tried again, mixed new batch of XXX but left a little in glass cup to See if what I thought was happening actually was, CURSED the carb change, soldered the butterfly back to original shape, tried to start, considered a drop kick over the fence, looked at fuel sample, CURSED FUEL, made picture. etc. I'll get some "real gas" later.

As to the ST 51 Mutant, I like that! The short of is that I turned down the front of the engine and made a manifold for a Walbro to run gas. The manifold was not aluminum, but some unknown composite. It failed. I decided to put the stock carb back on so I cut a new adapter out of aluminum. I offset the carb for the "Coolness factor" and because I wanted to see if the carb mounted in a plane with the needle at tank center would make a difference. Kinda like side mounting an engine but this time only the carb. This is part of the "Muffler pressure with gas question". Tank center line etc. So far I think a long pressure tap with maybe an aluminum tube would cool any gas problem. Tygon will not handle the heat, so Silicone to aluminum? Ch ignition with Syncro spark as mentioned earlier on gas and 20% synthetic oil, the same fuel as the gas mag ignition evolution in a previous picture. That's the short version? The mount mess is the adaption of the ST mount to the Weedeater mount that was in there first.

the only ST pictures I have.