Check out this spark plug
 

So I got this 83 rx7. doing the fix it up thing. always thought it was a bit under powered. Plugs looked good when I got it, so I left em in. After fule pump and carb rebuild. It started and idled. . Had a little miss when I accelerated. So I pull the plugs again see if they are fouled. Crazy. the top of the plug pulled out of the ceramic
. Never had that happen before. It was the top plug on the engine. Had to order a replacement set, so I don't know if it will run stronger. Will a rotary run with only the bottom plug sparking? SC

it should run better with new plugs....

The top plugs are the trailing plugs, which are mainly to just clean up the unburnt hydrocarbons. The bottom plugs are the more important plugs.

It is amazing what these engines will run with and without, had one of the young guys swing by my place one weekend complaining car had no power .... so after investigating it turns out he was not getting spark to the trailing plugs ... after changing the ignitor it still ran but still no power .... so I take out the compressor tester and we check it .... something like 85's on the front rotor ... o yes zero on the rear rotor ... so long story short he was driving on just the leading plug working on the front rotor ... thats it


sadly he bailed and purchased a firechicken :(

But yeah once you have 4 nice working plugs she should run like a top

trailings really won't affect power or drivability much, as mentioned they are mainly for emissions and to top off the power band of the engine.

the issue you may notice though is this is a dizzy distributor, which has a cap and rotor which can cause arcing to other plugs if there is enough resistance which will cause a real noticable drop in power and severe hiccups in the higher RPM range.

Great info. just maybe this will do the trick. I am using a ton of gas. I'm at 160 miles and the tank is down just above E. I'll take alook at the distributer. maybe there will be lots of black soot if its arcing around

Smellycat, these cars on average get 20-22 mpg, what are you running at?

I'm not sure on the mpg. I will fill er when I get these plugs are in.

the distributer had one post that was all gnarly. it was one of the four deep in the cap. stay tuned. sc

Ok. in go the plugs, scrape smooth out the gnarly dist post.

Wow Wowzer McWow.
Starts up with no Choke. Very hard to do until today
Shifts better.
I think it holds in the higher rpms longer and the gears are matching up better

No backfires when I shift after a stomp on the pedal for fun.
I Kind of miss the backfire

Motor even sounds different. silky smooth.
It was cool before but now its like a cat purring

I'm hoping the new plugs cure the leak of death. Although its fun when I'm at a red light and all this funny smelly smoke starts wafting out under the car.

Cheers to all. SC

Just found out I got 19 MPG running with 3 plugs. Cant wait to see the mpg with 4 plugs working

I drove mine for about a year when I first bought it with the plug wires reversed (leading to trailing). Really woke it up and averaged about 25mpg after I switched the wires back.