My raceteam's '81 RX-7 has a 12A street port with a Weber 48 IDA carb. We currently run BR10EIX Iridium spark plugs. The car is run in SCCA/MCSCC road races but also does track days and autocrosses. The problem is that the car is really difficult to get started, especially when cold. The car has an obvious distaste for idling as well.

I think NGK says that we're supposed to start the car with normal plugs and then switch to 10's once it's warmed up, but that's not really practical for us.

We're trying to figure out if the hard starting can be cured or if it's just the nature of the beast. Is it safe to run 9's on a 12A SP race motor? Would doing an MSD install help compensate for running the race spark plugs? Any other thoughts?

 

hard starting? 2 issues come to mind: timing is off and issues with idle circuit.

Yes, hotter ignition system helps with starting. You can just run DLIDFS so there is no need to spend $$$ on a MSD box.

I have run B8EV to B10EV including Autolite race spark plugs (cant remmber the #). No starting problems since I have a MSD box.

 

Thanks.

The carburetor may be part of the problem. We never really tuned it, we just run what was recommended to us for a 12A street port.

EGT's are around 1000 degrees at 2000 rpm (idle) and 1600 degrees at speed. Sometimes it feels like the plugs are getting carboned up and it starts to idle lower. A few blips of the throttle usually helps.

I guess our best bet is to continue to run NGK 10's and try to deal with it in other ways.

 

I would also suggest that you check the timing. Where in Michigan are you?

 

+1 on timing I had the same problem on my car. I rest the timing and it starts really well now.

 

I know we checked the timing recently, but I suppose we could check it again.

Our shop is in Otsego.