It is best to do what av8tor said.. He has alot more time in gas/glow then I do.. I know that I had a carb have dryrot that is were I came up with mine.. but av8tor has all the time and work in it to know.. sorry for the bad post lol

There are people who do use ATF as after run oil in Gas-Glow.
The glow fuel is hard on the diaphram in the Walbro Carb.

The ATF flushes the glow fuel out and keeps the diaphram flexable.

av8tor1977
I've been following your post with some other forums and have a few questions for you.[X(]
In the Homelite 25CC motors there was a few questions about modifications one of the other members was working on. One of the modifications was on the carb, dealing with the larger carb and modifying the air hole and mounting plate adapter. You were saying that they needed to run a external line to the crankcase to ventilate it. Could you explain this modification and how it works? Why and how this would inprove the performance. Would it work with a gas/glow conversion motor.

The engine responds well to a larger carb such as one with an 11mm venturi. But you have to open up the throat in the plastic carb adapter manifold to match the carb throat. Often times, before you get to the point where it is open to the same diameter as the carb throat, you are either very close, or slightly into the carb pulse hole in the manifold. You will also get very close to the "relief" provided in the manifold for one of it's mounting screws. I fill the pulse hole with JB Weld, and I make a little dam and fill the area near the bolt hole relief somewhat and use a smaller headed bolt in that position. You can then bore out the manifold as far as needed without problems. Don't try to bore the manifold out with a drill, as it will catch in the soft material and probably ruin the manifold. I use a sanding drum in a Dremel.

If you look at the fuel pump cover on the carburetor, it has a couple of little raised round spots or bosses. These bosses are there for the installation of a fitting for a hose to run to any convenient spot on the crankcase for the pulse for the fuel pump. Some carbs come from Walbro with a fitting; the ones for applications using the manifold pulse hole don't. All you have to do is drill and tap the boss for a hose fitting and run a line to another fitting installed on the crankcase for the pump to operate. The fitting on the crankcase can be anywhere that is convenient, just make sure you don't leave any chips in the engine from drilling and tapping the hole.

This is a good modification whether the engine is run on regular ignition or Gas/Glow.

AV8TOR

Another great modification for the Homelite 25 is to send the piston to Frank Bowman and have him install a pin in the ring land and make you a ring for pinned use. Then you can grind out the bridge in the exhaust port for MUCH better flow because the ring won't be able to turn and get caught in the port.

A Homelite 25cc I did for a friend has the 11mm carb, a free flowing muffler, the base gasket left out to raise compression, and the above modification. With no porting or other hop ups it turns a 15 x 8 APC prop at 9400 rpms. It will turn a 16 x 8 at around 8700.

AV8TOR

Thank you for explain the pulse line system. I've seen these in the back of glow engines and didn't know what they were. What increase in RPM do you think could be had from this type of modification?
With this modification, how do you know what tolerances there are in line diamiter so as not run the motor out of fuel?
What Do you have a phone number or address for the man with the rings? So I could call him? Could a second ring be installed with a pin to further increase compression?
What is the fastest RPM you have seen for yourself a Homelite 25 run? I've had guys tell me 11,000 RPM turning a 18x6 prop? I thought they were just BSing me.
Do you know of a higher RPM bearing that could replace the stock ones?
Do you know were I could get the tolerances for these and other motors that are used for conversions?
Could you explain a stuffing the case term and how it could be accomplished. Lots of questions

ok, I figured I'd ask here since this might get the most attention...

anyone played with the bigger engines and tillotson carbuerators with gas/glow yet? do the diaphrams hold up? I don't have any Walbro's big enough for my 51cc engine and don't want to try the original carb since it's funky... I know Tillotson's are supposed to be good units, but I haven't heard anything about using them for glow fuel that I've seen...

I'll get the all up weight of my new monster with and without flywheel and compare it to my mac 32 before I make my final decision on whether to use gas/glow or magneto...

The place for rings is:

Frank Bowman
1211 N. Allen Ave.
Farmington, NM 87401
ph# 505-327-0696
e-mail [email protected]

Chicks5 -

Thank you for explain the pulse line system. I've seen these in the back of glow engines and didn't know what they were. What increase in RPM do you think could be had from this type of modification?

IT'S AN ENTIRELY DIFFERENT DEAL WHEN YOU SEE ONE ON A GLOW ENGINE. WHEN YOU SEE A PRESSURE TAP ON A NORMAL GLOW ENGINE, IT IS TO PRESSURIZE A FUEL OR SMOKE OIL TANK; NOT OPERATE A PULSE TYPE FUEL PUMP. (IN MOST CASES.) AS FOR RPM INCREASE, I HAVE NEVER DONE A "ONE AT A TIME" MODIFICATION PROGRAM SO I CAN'T TELL YOU WHAT EACH AND EVERY MOD WILL DO BY ITSELF. AN ENGINE HOP UP PROGRAM SHOULD BE A COMBINATION OF THINGS THAT WORK TOGETHER/COMPLIMENT EACH OTHER.

With this modification, how do you know what tolerances there are in line diameter so as not run the motor out of fuel?

FUEL DOES NOT FLOW THROUGH THIS ADDED ON TUBE. THE TUBE IS FOR THE PULSE THAT OPERATES THE FUEL PUMP. AS FAR AS FUEL FLOW ITSELF, NO WORRIES, THE CARB CAN SUPPLY PLENTY OF FUEL.

What Do you have a phone number or address for the man with the rings? So I could call him?

HIS NAME IS FRANK BOWMAN. I DO NOT HAVE HIS CURRENT E-MAIL OR PHONE NUMBER. POST AGAIN AND SOMEONE HERE WILL PROVIDE IT.

Could a second ring be installed with a pin to further increase compression?

I'M SURE IT COULD, BUT I REALLY DON'T THINK IT IS WORTH IT.

What is the fastest RPM you have seen for yourself a Homelite 25 run? I've had guys tell me 11,000 RPM turning a 18x6 prop? I thought they were just BSing me.

MY HOMELITE 30CC IS EXTENSIVELY MODIFIED AND TURNS AN APC 16 x 8 PROP AT 9400 RPMS PLUS ON THE GROUND. I IMAGINE IT UNLOADS TO AROUND 10,000 IN THE AIR DURING CERTAIN FLIGHT CONDITIONS. THE BOATING GUYS REGULARLY RUN THEM AROUND 10,000 RPMS OR SO. AS FOR 11,000 WITH AN 18 X 6?? VERY DOUBTFUL UNLESS THEY ARE RUNNING ROCKET FUEL OR NITROUS....

Do you know of a higher RPM bearing that could replace the stock ones?

THERE ARE HIGHER QUALITY BEARINGS OUT THERE, YOU COULD TRY BOCA BEARING, BUT IT IS ENTIRELY UNNECESSARY. THE STOCK BEARINGS WORK FINE.

Do you know were I could get the tolerances for these and other motors that are used for conversions?

NO.

Could you explain a stuffing the case term and how it could be accomplished. Lots of questions

STUFFING THE CRANKCASE RAISES THE SECONDARY COMPRESSION. IT IS DONE ON THE HOMELITE ENGINES BY ADDING A PLATE TO THE BACKPLATE TO REDUCE THE VOLUME OF THE CRANKCASE. BE SURE TO ALLOW FOR A MINIMUM .015" CLEARANCE FROM CRANKPIN TO BACKPLATE.

YES, LOT'S OF QUESTIONS....

GOOD LUCK,
AV8TOR

Thank you for the information and your Patience.

AV8TOR

Capt,n

Hi Captain! How are you feeling?

AV8TOR

i am going to buy some more nitro soon but the model only has a 10% nitro with 18% synthetic oil[&:]

would 18% synthetic be a problem? i assume you just lower the oil content of the gas a bit?

i hope you're ok too capt'n!

shaun

That's too much oil by nearly double. See if you can find pure methanol somewhere. Then buy 20% nitro 18% oil glow fuel and mix it with one gallon of methanol. (Methyl Alcohol) Then mix that with two parts of high test gasoline for the proper Gas/Glow mixture.

You can't just use gasoline to water down high oil content glow fuel, as this will also decrease the methanol in the mixture which is vital to the glow plug operation.

AV8TOR

they DO have 15% nitro and 10% oil[&:]
but i think tht is too much nitro and i will need to make carb mods[:'(]
i don't think i can buy pure methonal anywhere (living in australia can mix any model fuels by yourself)
will 15% nitro work? water it down with gas maby? (if gas wont water down oil will it water down nitro?

shaun

Try the 15% nitro and 10% oil. It should work fine. If not, you can just lower the compression ratio a touch, but it should be no problem. Don't add extra gas to the mixture. 2 parts high test gasoline to 1 part glow fuel.

AV8TOR

The reason Gas-Glow works is that the methanol reacts to the platinum wire in the glow fuel.
You need right at 1/3 methanol a little less and it will quit working.

Larger quanities of oil should only be used in test batches.
The lower the compression the more nitro you need to use.
When you remove power to the glow plug and the idle drops more than a little bit
You need:

1) More Nitro

2) To raise the compression
a) new rings... If you are dealing with an older engine this may take care of a lot of problems.
b) remove material off the flange on the bottom of the cylinder.
You need about .020 clearance between the piston and the head, this is called the Squish Band.

The reason Gas-Glow works is that the methanol reacts to the platinum in the glow fuel.
You need right 1/3 methanol a little less and it will quit working.

You should not need to make carb mods. because of nitro. Maybe because of the methanol.
It takes more methanol than gas to run an engine/

Yep...

AV8TOR

AV8TOR: I am feeling a lot better...but have to be carefull and not raise left arm too high. Some pain around pacemaker...but not bad. Capt,n

good to see you posting you are ok capt'n

so then if i had a REALLY high compression engine i prolly would not need nitro at all? (this does not mean i will do it)
might be interesting for somone to try.....

i ordered some 10/11 (10%nitro 11%oil) just then.

thanks a whole heap guys!!!
shaun

Glad to hear you're doing ok and getting better Captain.

shaunmichaeljohnson - These conversion engines tend to be fairly low compression and like the nitro for the most part. But that is true; if the compression were high enough the nitro wouldn't be necessary. However, a slightly lower compression ratio used with nitro makes more power, and has a nicer idle and transition to higher rpms than an engine without nitro.

AV8TOR

okay i know this is a plane forum but im going out to cut the chassis plate today to fit the 46cc poulan into my savage. . the stock carb has a plug in it somewhere so i took a wt 454off a 31cc ryobi and willl try that. i have a veriety of fuels available and will post my tests and runs.

If it is the stock carb that came with the Ryobi, it is way too small for your Poulan 46cc...

A 46cc engine should have a venturi that measures at least 13.5mm.

AV8TOR

the butterfly is about 12.5 so ill try that, i can always go up. this stock carb has me baffled how it works.