On using Loctite for glow plug threads...
04-20-2003, 12:33 AM
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On using Loctite for glow plug threads...
Hey Guys, don't use "Blue Loctite" on the glow plug threads.
Years ago, I was a sales engineer for Loctite (Corp) [R], and I've had some experience using the stuff.........
Use only "Loctite 222" on those Cox parts. 222 is light purple, and is much weaker than "Blue". By the way, Blue is 242. The 222 is essentially a sealant, with low breakaway torque. The 242, while classified as a medium threadlocker, is usually too strong for small, aluminum (soft) parts.
Be sure to clean the threads first with dope thinner, etc., LET DRY THOROUGHLY, apply the 222, assemble the parts, and warm the head with a BIC lighter or equivalent if you're in a hurry to run the engine.
Comments to:
Duie
[email protected]
Years ago, I was a sales engineer for Loctite (Corp) [R], and I've had some experience using the stuff.........
Use only "Loctite 222" on those Cox parts. 222 is light purple, and is much weaker than "Blue". By the way, Blue is 242. The 222 is essentially a sealant, with low breakaway torque. The 242, while classified as a medium threadlocker, is usually too strong for small, aluminum (soft) parts.
Be sure to clean the threads first with dope thinner, etc., LET DRY THOROUGHLY, apply the 222, assemble the parts, and warm the head with a BIC lighter or equivalent if you're in a hurry to run the engine.
Comments to:
Duie
[email protected]
04-20-2003, 01:46 PM
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Compression....
Hi Duie,
Good point on the LocTite. I think that this got started with a post from Andy W. Andy mentioned that the space between the threads and maybe associated leakage is a real killer to 1/2a engine performance. It's amazing how much performance can be influenced by a teensy weensie change in combustion chamber volume. Point here is if performance is important to you, make sure you check this out. And, while were at it, if your engine uses the little copper or brass shims under the glow head, be sure these are clean and no burrs on them when you assemble the top end. If in any doubt, burnish on a piece of 600 paper lightly oiled on a flat surface, like a piece of glass. Just use your thumb in a figure eight pattern. You'll see the oxidation go away and any dings will be easy to spot. Make sure that the mating surfaces are clean and dry. Assemble and snug her down good and tight, and your good to go... Rgds, Jeff....
Good point on the LocTite. I think that this got started with a post from Andy W. Andy mentioned that the space between the threads and maybe associated leakage is a real killer to 1/2a engine performance. It's amazing how much performance can be influenced by a teensy weensie change in combustion chamber volume. Point here is if performance is important to you, make sure you check this out. And, while were at it, if your engine uses the little copper or brass shims under the glow head, be sure these are clean and no burrs on them when you assemble the top end. If in any doubt, burnish on a piece of 600 paper lightly oiled on a flat surface, like a piece of glass. Just use your thumb in a figure eight pattern. You'll see the oxidation go away and any dings will be easy to spot. Make sure that the mating surfaces are clean and dry. Assemble and snug her down good and tight, and your good to go... Rgds, Jeff....
04-21-2003, 11:43 AM
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On using Loctite for glow plug threads...
Hi Jeff:
Your point on combustion chamber volume is very important indeed.
As a very young modeler (in the early 50's), my brother had a Spitzy .045 glow engine. No matter what we did, the engine would only run out a prime and quit. I can't tell you how frustrating it was. We went through many starting batteries and pints of 'Testors 39', but the engine refused to run on more than the prime.
Last year, I dug the engine out of storage, determined to get it to run. Sure enough, even with "all these years" of experience, the engine would only run out the prime. Still frustrated, I began experimenting with plugs. Still no change. Then, quite by accident, I left an extra washer under the plug on a changeout, and the engine RAN ! For the first time in over 50 years, it actually ran ! I removed the extra washer, and, sure enough, it wouldn't run. Put the extra washer back in, and, like magic, the engine started and ran well.
To me, this was proof that glow plug element placement in the combustion chamber, and combustion chamber volume were, indeed, critical.
Yes, the LOCTITE 222 will both lock and seal the threaded area, and help in getting more consistant engine runs. I cannot agree with those who suggest inserting a piece of nylon string-trimmer line into a drilled hole in the threaded area, or the use of excessive installation torque as a means of eliminating the loose plug problem.
Best regards,
"Duie"
[email protected]
Your point on combustion chamber volume is very important indeed.
As a very young modeler (in the early 50's), my brother had a Spitzy .045 glow engine. No matter what we did, the engine would only run out a prime and quit. I can't tell you how frustrating it was. We went through many starting batteries and pints of 'Testors 39', but the engine refused to run on more than the prime.
Last year, I dug the engine out of storage, determined to get it to run. Sure enough, even with "all these years" of experience, the engine would only run out the prime. Still frustrated, I began experimenting with plugs. Still no change. Then, quite by accident, I left an extra washer under the plug on a changeout, and the engine RAN ! For the first time in over 50 years, it actually ran ! I removed the extra washer, and, sure enough, it wouldn't run. Put the extra washer back in, and, like magic, the engine started and ran well.
To me, this was proof that glow plug element placement in the combustion chamber, and combustion chamber volume were, indeed, critical.
Yes, the LOCTITE 222 will both lock and seal the threaded area, and help in getting more consistant engine runs. I cannot agree with those who suggest inserting a piece of nylon string-trimmer line into a drilled hole in the threaded area, or the use of excessive installation torque as a means of eliminating the loose plug problem.
Best regards,
"Duie"
[email protected]
