The clutch in my mind? or the one in my car which isn't - works fantastico and only has 20,000 miles on it.

I think the rpm issue may be due to the distributor signal to the tach. It happens every once in a while.

Ya, spark plugs really can't change cruising rpm ;)

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When I had my 626, I used NGK... That engine was finicky when it came to the spark plugs used - but there's something to be said about using the plug the drive train was designed for (or, at the very least, thought about) :p

What's "It", exactly? In CRXs, an irratic tach reading is a sign that the either your battery is almost dead due to a failed alternator, or your ignitor unit is on it's last legs. The ignitor unit does the grunt work of switching power to the ignition coil. It apparently also does some monitoring of the coil's state of charge each time it fires and adjusts the power on and off timing to minimize power usage. If the NGK and Bosch plugs have different electrical characteristics, it may be affecting the ignitor unit's reading of the coil, or be pushing the dying ignitor and/or coil beyond their capabilities.

me too. now i am wondering if the chinese are making knock off ngk plugs....

i am pretty baffled ...:thumbdown:

Bobski's on the right track I think.

If the dizzy is original, then it might explain some of the strange behavior. I have a spare dizzy I bought a few months ago but I have a policy of not changing parts until they give me obvious trouble.

Well, I would swap in your other dizzy with the bosch plugs to make sure it's working properly, then install the NGKs to see if the problem is your old distributor. If the symptoms are gone, your old distributor was giving you obvious trouble, so it warrants replacing. :)
If the new distributor has the same problem, your old one was fine, so you can swap it back in without putting any miles on your spare.

Something else that just came to mind... Are the little screw-on contact things on the plugs the same size between the two brands? I could see larger contacts on the Bosch plugs possibly stretching out the clips on your sparkplug wires so they don't make proper contact with the ones on the NGK plugs.

No, I didn't think about the other end of the spark plug - good one. When I have nothing else to do I just might swap out the dizzy. I probably will need to adjust the timing so more work to do than just the dizzy itself. It would help to answer the question so thanks for the suggestion, bobski.

interesting... are the wires ngk as well?