I know that the spark plugs are supposed to have the three electrodes at the top. When I pulled the plugs out of the engine they were plugs with only one electrode, like in a piston motor. My question is, what does this do to your engine?

 

I would just buy the right plugs. I don't think it does anything to the engine except make it run poorly. If it's way far away as far as heat range goes it could really run poorly or not run or cause damage due to pre ignition. I think it would just run poorly though. Your up late like me. Weirdo! I feel like a meth addict sometimes. But I swear I can only get **** done when everyone is asleep so they can't bother me. lol

 

Well, I work until midnight, so I gotta wind down. What better way than to learn more about my car

 

If the plug projects to far into the rotor chamber it could damage the apex seals.

 

Get the correct OEM plugs for your car. They must have the correct threads, of course, and they must have the correct "reach". The reach is especially important for rotary engines as too much reach can damage the apex seals. Piston engines just hammer the electrodes if they extend too far. Get the correct temperature range plugs, too, since otherwise they will either foul too easily (if too cold), or the glaze will burn off the porcelain , leading to fouling (if they are too hot).

All plugs are pre-gapped at the factory (been that way about 40 years). If you have an SA or REPU with mechanical points then you'll need plugs with a smaller gap than would be used with an electronic system. Therefore, the plugs recommended for the 81-85 RX-7 will work very poorly in an SA or REPU. Mechanical requires a plug gap of about 0.030 and electronic about 0.060.

 

Interesting this one. I once bought a 2nd hand 1984 1st Gen Series 3 (only one model at a time here in England, as you probably know). It went great on a test run so I put down the deposit and arranged to collect in a couple of days. I asked the supplying dealer not to service it as he was no expert and I figured I could do it better.
Well the guy must have felt helpful because he did 'service' it. The car overheated all the way home (about 45 miles) and it took me 2 full days of radiator out, timing checks and everything else I could think of, until I pulled the plugs! He'd put Champion 2 point things in - from what spec car I've no idea.
So one consequence of wrong spec plugs is certainly overheating on a big scale!
Why not send it straight back? Well the car was good on the test before the service so it had to be something simple! It was, I just didn't think clearly enough.

 

RX's need multi-electrode plugs because of the high and lack of cooling between cycles. The car will run w/ single electrodes, but the potential for melting down a plug exists.

 

i heard they can damage ur apex seals when i was down in NJ, what i did with a friend was, put in my old plugs in to his, let it run for a week, everything was fine tho