PetesPonies

well a Dizzy is a distributor. As far as ignition timing goes, you can play around with it and see when the engines runs best or fastest. One thing to watch for is detonation. When it is audible it's easy to tell it is happening. Problem is the onset of detonation is unaudile to the human ear and damage could be occuring. When and if you here detonation, back off 2 degrees to try to make sure you have removed it. Or you could try a higher octane gasoline, as well as a richer mixture, cooler spark plugs etc. Pete's Ponies Mustang RUSToration ( just bought a 240Z)

I believe the 280Zs came with a 195/70 . Assuming that it was supposed to be the same height, you are looking at 24.7" tall. Aspect ratios on old tires were 78, not 80. Plug a 78 ratio into a 175 tire and the overall height is 24.7", exactly the same height as the 195/70 -280Z tire.

no such thing as a 175/80/14 tire

guys, it's not the size or profile that is important or wrong, it's the overall tire diameter, or circumference. If you keep that the same, your speedometer wil always be correct. Just like changing the rear end gear, a different speedogear on the cable will solve sppedo error anyway. Take the section width of the tire ex 215. Multiply this by the aspect ratio 215 X .60 = 129mm. Multyiply this by 2 ( two sidewalls ) and then divide by 25.4 ( to convert to inches). 258 / 25.4= 10.15. Add the wheel diametter to this 10.15 + 14 = a tire that is 24.15 inches tall( diameter ). A stock 175 /70/14 was 175 X .70 X 2 / 25.4 + 14 = 23.6. So a 215/60/14 is .55 or 1/2" taller. The 195/70/14 is 24.7 tall. You can go to 15" or 16" tires and keep the same height, just use lower profile tires.

interested in the wheels. How wide are they, offset?? Do you have a pic?