Spark plugs

[Bird]

Just picked up new old stock never opened 4B2-S sparkplugs (36 of them) did I screw up? Was there more modern plugs for the lycoming and contental?

[Edwin Otha]

Re: Spark plugs

Bird,
Those old BG plugs will be fine. That amount will keep you in plugs for a few years. Some of the BG's used a little 5/8th plug end that is getting harder to find.
I did about the same thing with some Champion obsolete plugs and they are working great.
EO

[Guest]

Re: Spark plugs

Fresno Airparts has the harness fittings that you will need as well as complete harnesses.

Dave

[Frank DeBartolo]

Re: Spark plugs

I need to get a shielded harness and plugs. I know where to get the harness and plugs, but does anyone know where I can purchase the eyebrows that go on the cowl to accomodate the longer plugs?

Thanks,

Frank D
N43684

[Bird]

Re: Spark plugs

These plugs have 2 different size nut(?) for instalation, 9/16 and also 11/16, one above the other, I've never seen that before, no 5/8 size on the plug at all.

[Guest]

Re: Spark plugs

That' s the way that BG makes plugs.

Your old harness nut probably is too big to fit on the plug. The harness nut that fits is 5/8" hex not 3/4" like most modern harneses.

That's what the other fellow was talking about. You can get all set up at Fresno Airparts.

Dave

[Hank Jarrett]

Re: Spark plugs

Frank,
There are lots of guys with the blistered cowls for the long plugs, but the original un-cut cowls are kind of hard to come by. Why not trade with someone who wants an un-cut cowl? It's a lot easier to cut a hole in an original cowl than it is to patch a cut one!
Hank

[Bob Waldron]

Re: Spark plugs

Bird,

I suspect that the plugs that you purchased are too long for a closed cowl Taylorcraft (anything newer than 1940). Also, 'normal' shielded aircraft spark plugs have a threaded barrel that allows you to attach them to the threaded connector on the shielded ignition. 'Normal' shielded aircraft spark plugs have a 5/8 inch or 3/4 inch barrel and you would need a shielded ignition harness with 5/8 inch or 3/4 inch fittings on the ends. The 5/8 inch barrels and fittings are the most common.

I suspect that YOUR sparkplugs have a 9/16 barrel. This is a RARE setup that seems to only have been used just before WWII. I have a few military WWII engines that have these 'narrow barrel' plugs.

If your plugs have the narrow barrel, you would have to have a special wiring harness fabricated for your engine, and that harness can never be used for the most common wider barrel plugs.

If your airplane has a closed 'pressurized' cowl, your new sparkplugs will require the installation of 'bumps' in the front-top of the cowl, to accommodate the tall plugs. If your airplane has an 'open' cowl (with 'eyebrows' over the exposed cylinders, AND they are the narrow barrel plugs, you will have to have a special wiring harness fabricated.

[Guest]

Re: Spark plugs

Bird,

I suspect that the plugs that you purchased are too long for a closed cowl Taylorcraft (anything newer than 1940). Also, 'normal' shielded aircraft spark plugs have a threaded barrel that allows you to attach them to the threaded connector on the shielded ignition. 'Normal' shielded aircraft spark plugs have a 5/8 inch or 3/4 inch barrel and you would need a shielded ignition harness with 5/8 inch or 3/4 inch fittings on the ends. The 5/8 inch barrels and fittings are the most common.

I suspect that YOUR sparkplugs have a 9/16 barrel. This is a RARE setup that seems to only have been used just before WWII. I have a few military WWII engines that have these 'narrow barrel' plugs.

If your plugs have the narrow barrel, you would have to have a special wiring harness fabricated for your engine, and that harness can never be used for the most common wider barrel plugs.

If your airplane has a closed 'pressurized' cowl, your new sparkplugs will require the installation of 'bumps' in the front-top of the cowl, to accommodate the tall plugs. If your airplane has an 'open' cowl (with 'eyebrows' over the exposed cylinders, AND they are the narrow barrel plugs, you will have to have a special wiring harness fabricated.

Bob, I think the part in blue is wrong. You can just remove the terminal ends and change to 3/4" or 5/8".

There is no issue in swapping these ends.

Dave

[Bob Waldron]

Re: Spark plugs

Dave,

I think you are right and I stand corrected. I looked at my harness that is set up for the 9/16 barrels, and it looked like quite a bit of work in addition to the cost of purchasing the larger connectors. My setup does NOT have any extra wire on, so an error in replacing the connector, would probably result in purchasing a replacement wire. In addition, the connectors on the ends of my wires are unusually long, and it may be difficult to find long replacements. I agree with you though, that a 'narrow barrel' harness can probably be modified back to fit 'normal barrel' plugs, cheaper than purchasing a new harness.

I wonder what Lycoming O-145 harnesses selling for these days?

[Bird]

Re: Spark plugs

efully this picture will get on here.

[Bird]

Re: Spark plugs

The plug on the bottom is the new one, the one on top is just a 4B2 not shielded I believe

[Bird]

Re: Spark plugs

And if anyone wants some of these, the guy that has them is on Ebay, his store is SATURN SURPLUS $22.50 for 6 plugs, I think he has over 300 more of them.

[Edwin Otha]

Re: Spark plugs

Bird,
The two wrenching hex's are for disassembling the plugs. With this plug you can replace components and reseal the plug. I have the equipment to do this but ran out of spare parts years ago.
The plug looks like it will fit a standard harness. Try to screw on a plug lead. Did you say he had some of the unshielded plugs?
EO

[Bird]

Re: Spark plugs

No he just had the shielded ones, I put the shorter one there for comparision