Tony 260Z
Club Member
I wonder whether anyone can help here 'cos I'm beginning to get a tad p*ssed-off with my lovely Z. She's a 1978 260 with 240carbs, lumenition ignition, K&N's, a nismo 6-2 header and 2 1/2" system.
Anyway, I'm currently getting through a spark plug with every trip. On a hot day, I can start the car without the choke, leave her to warm up for a couple of minutes and then drive fine. However, if I need to start her on a colder day (ie almost every day the way our weather is at the moment), then I need the choke for a minute and the problems start. She will idle fine, and warm up fine too, but as soon as I start to drive and accelerate she'll stumble and misfire. If I then stop and check plug#3 I'll find it totally fouled-up with carbon. I swap in a new plug and she's right as rain. Bear in mind that I never use the choke for more than a minute, and never try to drive away with the choke on either.
I've checked the piston movement in the front SU and it seems fine. Mixture seems OK (when warm, anyway). The ignition lead is OK too. Compression is good. The timing and everything else I can think of checks out (more or less, as I couldn't get the dizzy alignment on the oil pump drive to 100% perfect - it's a degree or two out there).
Apart from this problem she drives perfectly well. As soon as I dump the fouled plug and stick in a nice new shiny one she's fine - until I need to start her cold again.
What is the problem? Any ideas? I'm getting through NGK's at such a rate that Mike Feeney must think I'm eating the blasted things. I had to stop the car in the rain last night to change the plug. Again. How annoying is that?
HELP!
Tony
Anyway, I'm currently getting through a spark plug with every trip. On a hot day, I can start the car without the choke, leave her to warm up for a couple of minutes and then drive fine. However, if I need to start her on a colder day (ie almost every day the way our weather is at the moment), then I need the choke for a minute and the problems start. She will idle fine, and warm up fine too, but as soon as I start to drive and accelerate she'll stumble and misfire. If I then stop and check plug#3 I'll find it totally fouled-up with carbon. I swap in a new plug and she's right as rain. Bear in mind that I never use the choke for more than a minute, and never try to drive away with the choke on either.
I've checked the piston movement in the front SU and it seems fine. Mixture seems OK (when warm, anyway). The ignition lead is OK too. Compression is good. The timing and everything else I can think of checks out (more or less, as I couldn't get the dizzy alignment on the oil pump drive to 100% perfect - it's a degree or two out there).
Apart from this problem she drives perfectly well. As soon as I dump the fouled plug and stick in a nice new shiny one she's fine - until I need to start her cold again.
What is the problem? Any ideas? I'm getting through NGK's at such a rate that Mike Feeney must think I'm eating the blasted things. I had to stop the car in the rain last night to change the plug. Again. How annoying is that?
HELP!
Tony