Spark Plug Adapter question Continental A65

[Tom G]

Hello everyone: Was doing a spark plug change on my airplane and when removing one of my top plugs (with the ercoupe cups installed) the cup came off with the plug and also pulled out what appears to be an adapter that was threaded into the cylinder. I took it to my mechanic but even he could not separate the spark plug from the adapter so the spark plug, the cup and the adapter are all stuck together. I never even knew that there was an adapter in the cylinder that appears to be for using a smaller plug. At this point it appears i will need to get everything separated somehow since i want to continue to use the cup.

Does anyone know if these adapters are available anywhere. Like i said i never even knew they existed.

I think i'm going to do away with the cups and use shielded plugs in the top positions like i have in the bottom What i'll need to do is get those cowl bumps. Does anyone know if the cowl bumps are available anywhere or have any they would like to sell?

Thanks very much and sorry for the multiple questions.

Tom Gilbertson
Cranford NJ
BC12D 8016 N95716

[3Dreaming]

Fresno Air Parts has them in standard and three oversizes. Here is a link to one of them, https://www.fresnoairpartsco.com/pro...ng-spark-plug/ . Refer to the manual, but I believe that the should be drilled and pinned in place with a brass pin.

[Scott]

Yes should be pinned.
the inserts are the repair for previously damaged threads.

make sure you use C5a or similar antiseize compound on the sparkplug threads so it won't get stuck again.

[Hank Jarrett]

I would NOT cut up a nice cowl and put bumps on top. There are lots of "molested" cowls out there and those of us who dislike the bumps treasure any cowl that hasn't been butchered up yet. I would be happy to swap a cowl top with bumps for yours without. Better yet, put in new thread repairs as advised above and keep your cowl nice! A good machinist should be able to remove the thread repair from the plug (it will destroy the old insert, but you will be putting a new one in the engine anyway) or just take a look at the hot end of the plug and see if it needs replacing anyway. The Ercoupe cup will come right off once the thread insert is removed or if the plug is bad anyway when the threaded end of the plug is cut off. PLEASE don't mess up your top cowl!

Hank

[Tom G]

Hi Hank and thanks for your message. I have the cups on the top plugs and its never really been a great fit with the upper cowl. Just yesterday i discovered that the cup on the right side forward cylinder has worn a slight hole in the top cowl. I noticed it when i opened the cowl and saw light coming through it. I would really like to replace the cups with shielded plugs like i have in the bottom position and as far as i know the only way they will fit is with the cowl bumps. Do you happen to know if the rear cylinders need the bumps as well or just the front ones? I'm trying to cut down some ignition noise on my radio which is a handheld Delcom 360 mounted in the panel.

[Robert Lees]

...my radio which is a handheld Delcom 360 mounted in the panel.

I almost dropped my cup of coffee when I read this, so I must be mistaken. Does your Delcom 360 not have 720 radio spacing? Or am I missing something?

Rob

[Hank Jarrett]

Different planes seem to have slight fit differences. My cups get REAL CLOSE to the cowl but I don't think touch (I still have the bump cowl on the plane since I haven't finished making the new no bump top but if I put tape over the bottom of the bumps it doesn't seem to touch. I had plenty of room on the rear plugs but I have seen a lot of planes with either twin bumps or one really long one. I think if I couldn't get everything closed up without hitting I would either grind off the edge of the cup and weld it back or if I didn't have access to such a good welder I would consider metal bumping the cowl out a fraction of an inch for clearance. If it was blended in over a wider area it "might not" be too noticeable. Metal bumping i can do, my welding looks like wads of bubble gum.

Hank

[Tom G]

Thank you both for responding and i'm sorry for the late reply.

Robert, on the radio it does have 720 spacing. I'm not sure just what you mean. Is that more resistant to ignition interference?

Hank, I'm going to try grinding down the edge of the cup that certainly makes sense. I can see that if there is any way to avoid the bumps it should be tried.

Thanks to you both.

[Robert Lees]

Thank you both for responding and i'm sorry for the late reply.

Robert, on the radio it does have 720 spacing. I'm not sure just what you mean. Is that more resistant to ignition interference?

Hank, I'm going to try grinding down the edge of the cup that certainly makes sense. I can see that if there is any way to avoid the bumps it should be tried.

Thanks to you both.

Tom, nothing to do with interference, to my knowledge. I thought 360 radio spacing went out with the Ark and is illegal?.

720 is common in the USA (and other non-European) countries...in Europe we have to comply with 8.33MHz radio spacing.