converting gas to glow
11-25-2002, 05:46 PM
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converting gas to glow
can anyone tell me how to convert a gas carb to glow? i know you have to drill out the jets, but how much and which jets?where the needle valves go? HELP! thanks guys./
11-25-2002, 06:01 PM
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converting gas to glow
Measure all the fuel passages. Most carbs have a small aluminum plug over the low speed needle that has to be taken out to drill out the three small holes under it...It will be destroyed when you take it out, so get a new one...Double the AREA, not the diameter, of the three small holes under the plug..Drill out the main fuel inlet needle hole to about .080, clean off the burrs..Drill the high and low speed needle holes larger, but not enough so that the needles no longer work...Do not change the stock setting for the inlet needle lever, usually flush with the floor of the casting next to it...The carb will adjust just like a gas carb, except the low and high speed needles will probably not be at the usual 1 1/4 to 1 3/4 setting..
Look on the B&B website, I think he has a way to do it also....
Look on the B&B website, I think he has a way to do it also....
11-26-2002, 11:24 PM
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converting gas to glow
thanks rcign. not sure what you mean about increasing the area and not the diam. of the three holes but maybe it will be clearer when i get the plug out. couldnt find anything on b&b website. thanks for the info
11-27-2002, 02:01 AM
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converting gas to glow
It takes twice as much methanol as gas to run an engine, so the holes in the carb need twice the area..You have to measure the diameter of the hole, then calculate the area, then double it..
Example..if the hole is .030 diameter
the formula for area is pi(3.14) x radius squared
so..radius(.015) x (.015) x 3.14=.00070, the area of the hole
.00070 x 2=.0014, the area for the NEW hole..
Working backwards, The radius (squared) of the new hole is .0014 divided by 3.14=.000445..Radius is .021, new diameter is .042.....
This has worked for every carb I've done...
They needle and transition just as well as before conversion...
Bennett website, page 1, bottom of the page under glow conversion, instructions for converting carb, $1.00..
Probably easier than this....
Example..if the hole is .030 diameter
the formula for area is pi(3.14) x radius squared
so..radius(.015) x (.015) x 3.14=.00070, the area of the hole
.00070 x 2=.0014, the area for the NEW hole..
Working backwards, The radius (squared) of the new hole is .0014 divided by 3.14=.000445..Radius is .021, new diameter is .042.....
This has worked for every carb I've done...
They needle and transition just as well as before conversion...
Bennett website, page 1, bottom of the page under glow conversion, instructions for converting carb, $1.00..
Probably easier than this....
11-27-2002, 03:38 PM
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converting gas to glow
As a matter of idle curiousity-have you ever compared performance of a glowsetup with an ignition setup --using glow fuel?
My own experience is that tho the power increases - the glow ignition-- being what it is -- makes for rougher low end running and really no improvement on upper end - as long as the mechanical compression wes about right to begin with.
On a full bore engine - I cansee that simplicity is beter on glow - but on aerobatic stuff - the ignition on glow sure worked more smoothly-
It also consumed fuel at an alarming rate - but then-- that's what fuel is for --
My own experience is that tho the power increases - the glow ignition-- being what it is -- makes for rougher low end running and really no improvement on upper end - as long as the mechanical compression wes about right to begin with.
On a full bore engine - I cansee that simplicity is beter on glow - but on aerobatic stuff - the ignition on glow sure worked more smoothly-
It also consumed fuel at an alarming rate - but then-- that's what fuel is for --
11-27-2002, 04:01 PM
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A few years ago we went too high on the compression in a 289cc twin race engine..We had 5 glow plugs in each head, one in the center where the spark plug was and 4 more around the top..The center one melted and blew out, but the other 4 were still working..Flame came out the center during a heat race, melted the steel hex of the glow plug..We put spark plugs back in the center and used ignition with the glow fuel..It worked fine, no gain but no loss...We tried gas in the engine, lost about 400 rpm.
Methanol and glow plugs and methanol with spark plugs worked the same....The timing was set at 22 BTDC...We tried different settings, up to 30, but it ran just as well at 22 so it was left there...The current engine uses 2 glow plugs in each cylinder with lower compression and has not blown a plug in 2 seasons, and they're still in there..Methanol, 6% synthetic oil, and 20% nitro......
Methanol and glow plugs and methanol with spark plugs worked the same....The timing was set at 22 BTDC...We tried different settings, up to 30, but it ran just as well at 22 so it was left there...The current engine uses 2 glow plugs in each cylinder with lower compression and has not blown a plug in 2 seasons, and they're still in there..Methanol, 6% synthetic oil, and 20% nitro......
11-28-2002, 01:43 AM
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converting gas to glow
Burner, I don't know if you're clear but, diameter and area are two different measuments. If you double the diameter, the hole will be way too big.
11-29-2002, 02:48 PM
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area
Take a drawing compass and set it for 1 inch radius. Now draw a circle with it....and you will have a 2 Dia inch circle. Now if you double radius and draw a 4 inch Dia circle..... notice how much more area the 4 inch circle covers on the paper. That is why you do not want to double the Dia to get double the area. You should be able to see the difference now.......maybe! Thanks Captinjohn Happy Thanksgiving weekend to all
