I am stuck on the reason that the spark is weak on my 1980 rx7. Since I am working alone I removed all plugs and clamped them to a steel plate, then connected the wires and used a battery jumper cable to ground the plate direct to the battery terminal. When I crank I se small orange color sparks on the plugs. The plugs are not new but they are in reasonable shape, I have had this car since it was new and seem to either becoming dumb as I age or just missing something basic about the system. Any help is much appreciated. This is the picture of my test rig.

 

Does your car not run,not run well? How old are the consumables? Cap,rotor wires,air filter,fuel filter... plugs i can see and it could use a new set. How about some info on why you're looking at spark quality in 1st place. Freshen up mentioned tune up parts and see if that doesn't help your situation.

 

I can not get the engine to start, it has been sitting for a while. The original problem was that the car was misfiring under acceleration. I will follow you suggestions and just replace the basics and see if anything changes. I have pumped out all the gas and started new gas so far, but back to basics is a good plan. thanks for you reply

 

you might check coil voltage when its cranking vs not

 

Had a similar no-start with my 80 a while back.
Check existing plugs, they 'sparked' so I moved on.
-dropped in new dizzy cap and arm: nada
-check spark wires for connections: nada
-replaced igniters: nada
Finally went back to plugs. What did I have to lose? so I dropped in a new set:
BOOM.
instant start, ran like a Top. Jeez...

Stu A
80GS
AZ

 

^^^^this!!

 

Exactly!!! Spark plugs play a HUGE role in the way these engines run. I had an SE tbat had a small spot of corrosion on one of the spark plugs. Not on the ground but the head where there are no threads. I cleaned the corrosion as the engine was misfiring like crazy and the corrosion had caused the metal to pit. I pulled some used plugs off the shelf that still looked decent and cleaned them and installed them and the engine ran great. I drive up and ordered two new sets of BR8EQ-14's.

I would recommend duplicating your test with a new set of NGK plugs and seeing if anything changes.

 

First of all Thanks to all for suggestions. I am trying to get a new set of plugs local, but what are the best replacements for the original NGK BR8ET? Seems like so far I can only find the Champion RC12YC, any other options?

 

Thanks to all who offered help. In the end its back to basics to solve a problem. A combination of two failures at the same time can cloud the issue. Yes I had bad wires that where new along with failing plugs together. Changed all the parts plugs, wires, cap, rotor and it fired right. I was thinking that my last major carb rebuild and rats nest removal was the source of my problem when I first started to trouble shoot the issue. But checked all my work and the replaced new parts with newer parts and that was it.

 

Glad you got it running. Take the time to check and set ignition timing and carb idle mixture and speed.

 

As for spark plugs, I would only use the NGK BR8ET's. I would never use anything else.