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Can you can help me or direct me to someone who will be able to answer my questions? I have some old collectors' vintage model engines, and one I received recently has seized-frozen tight. Is there any way to un-stick such an old engine? I soaked it in Mystery Oil for two weeks; I boiled it to try to force changes in metal-part dimensions that might break it loose. No luck. Tonight, I plan to stick it outside in very cold weather [Alaska] to cause the contraction of parts; that might break it loose.

I'm sure it seized because its previous owner didn't clean it after its last run. Ordinarily, I would just buy a new engine, but these old engines are not easy to get. Any tips will be very much appreciated.

My other questions are also about very old collector engines. When a gasket has to be replaced, where can I find gasket material, and what's the best way to cut a gasket to size from bulk material? Again, since these old engines are no longer manufactured, the parts are not available in any hobby stores. [email]

CLYDE E. PEARCE

Clyde, let me first answer your gasket question: if you can't find a fitted gasket, I've had very good luck forming my own gaskets for old, out-of-- production engines using high-temp silicone sealant. It has really done the trick for me.

As for your frozen engine, you don't say what the piston and sleeve are made of, and of course, this does make a big difference. If they are both made of ferrous metals, they may have fused together because of acute, prolonged corrosion. Let's hope this isn't the case, as this situation is irreversible. I doubt that further freezing your "frozen" engine will do anything, but who knows? Perhaps an Alaskan night will crystallize solidified varnish into powder! Nah; probably not. Seriously, for a question about a vintage engine, I always defer to my mentors, Dave Gierke, Clarence Lee and Mike Billinton. Their years of experience make them far more qualified than I am in this case. Accordingly, I turn things over to my good friend "Dyno Dave" Gierke, who offers a step-by-step method that might work for you.

Good luck. -Chris

Hi, Clyde. There are two possible reasons for your antique engine's freezing:

1. The piston has rusted to the cylinder-if the combination is made of iron and/or steel (you don't mention the manufacturer or size).

2. The more likely cause is a gummed-up piston and cylinder; over the years, the varnish build-up has solidified. To free a gummed-up engine:

* Fasten a propeller to the crankshaft.

* Using a butane torch, heat the cylinder and head; carefully heat the fins evenly until the oil begins to smoke, and then stop.

* While holding the engine with an old pair of oven mitts, gently try to turn the propeller. If it doesn't turn over, apply more heat and try again.

* When the prop breaks free, carefully disassemble the engine and clean it with an engine cleaner such as Demon Clean that is specifically formulated for removing varnish.

If nothing budges after all this, the engine has probably rusted, in which case your only hope is to soak it in a penetrating oil over a few days and try again.

Depending on your engine's make and model number, gaskets may still be available! For further information, I suggest that you contact the Model Engine Collectors Association (MECA), P.O. Box 5, Sierra Madre, CA 91025.

-Dave Gierke

WHICH PLUG EQUALS WHICH?

I've been desperately seeking information on glow plugs and how a specific plug from one manufacturer compares with another. I posted this question on several online bulletin boards with no success. No one has come up with a source of information for me, but a couple of guys wrote that they are as confused as I am. I've noticed that this subject has come up recently in a few letters you have answered, and you, Chris, are my last hope. Can you help? [email]

MARIO FALCONE

Sorry, Mario. No one could come up with a cross-reference source of information on glow plugs from various manufacturers because none exists. The bigger problem is that there's no standardized glow-plug rating, and comparing manufacturer ratings is totally arbitrary. Simply put, when measured in the real world, brand X's "cold"-rated plug may turn out to equal brand Y's "medium"-rated plug. Coming up with a standard for all the plugs available from all the manufacturers out there would be a laborious and monumental science project that, so far, no one has taken on. Contrary to what some might tell you, all plugs are not created equal, and having the right plug will give you better, more dependable engine operation. The best example of this is still that the O.S. "F" plug will provide the best performance for all 4-stroke engines, regardless of manufacturer. I can, however, offer this: as is the case with fuel selection, going with the engine manufacturer's recommendation is the best place to start. This doesn't always apply; in the case of a 4-stroke, see what the experienced guys at your local field use. And remember: even if a plug glows when powered up by a battery, it isn't necessarily operating optimally. This is especially true if the plug is of a dubious age. When in doubt, replace the plug with a new one.

-Chris

SURGING MAGNUM

I recently purchased my first 4-stroke engine-a Magnum .52. I followed the engine's break-in instructions exactly, but at full power, it surges, and if I make any attempt to adjust the needle valve in either direction, the engine instantly quits. It has had two to three hours of run time, and I use Byron 15-percent-nitro/16-- percent synthetic/castor-blend fuel and a Fox 4-cycle glow plug. Please let me know what might be causing the problem. [email] KEVIN

OK, Kevin; first, put an O.S. "F" plug in the engine. Second, check the fuel-delivery plumbing for pinhole-size air leaks. Third, bring the engine up onto compression manually. After three to four hours of break-in, the engine should hold a good compression seal. If it doesn't, it won't have proper fuel draw and will run erratically. There are several possible causes of poor compression in a new engine: one of the valve clearances might have been set too tight, so the valve doen't rest completely on the valve seat. In a few Magnum engines, it took a very long time for the piston ring to fully seat on the cylinder sleeve. Check that the valve clearances are set according to the instructions (cold), and run the engine for another hour or so. If this doesn't help, it's time to send the engine back to Global for servicing. -Chris

TIME TO REPLACE THE PLUG?

Last summer, I purchased an ARF Hirobo Shuttle helicopter with an Enya .35 engine, and I greatly enjoyed learning to fly it. I use PowerMaster fuel; the first gallon was 15-percent-nitro RC aircraft fuel; the second and third gallons were 20 percent nitro, and the last two gallons were 25 percent nitro. The engine has a very smooth idle that is slow enough to disengage the clutch. The top-end power seems very good for hovering and flying circuits. I still use the original glow plug. In your opinion, how often should I change the glow plug and how long can I expect the engine to last? [email]

JIM HEBERT

Jim, it's hard to say how long a plug will last; plugs in sport 2-stroke and 4-stroke engines can last a very long time. Plugs in ducted-fan use have far shorter lives; hells fall somewhere in between, but closer to sport use. Being run often in hot, humid weather can shorten the life of a plug-and of an engine, especially if you tune it for all-out max power all the time instead of going for a slightly richer mixture.

Because hells are more sensitive to engine misfiring, which can cause drive-train vibration, the RC heli community considers plug replacement smart preventive maintenance, and I suggest you adopt the same view. Don't skimp on a fresh plug supply; the costs of replacing bent hell parts that result from an engine flame-out and consequent crash can add up really quickly!

Enya engines have some of the best metallurgy in the industry and, again, if you tune for a slightly rich mixture that supplies more oil and more expelled unburned alcohol (both of which carry away heat and yield cooler running), you will have that engine for a very long time. And, of course, don't forget proper after-run care. -Chris 4

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