cswistock

I replaced the exhaust front to back with a new header, 2" exhaust and new muffler. The old header leaked and all I smelled in the car was exhaust. So I don't think it is that. Also I set #1 to TDC on firing position and verified the timing mark (I thought the same thing). The timing seemed a bit advanced to me, but I don't get any knocks. Could being too advanced cause this?

I have a 72 240z. When I bought it two years ago it had a rebuilt engine, performance cam, header, stock carbs. The problems I have are it tends to run hot, gets poor gas mileage and the power seems to stall at higher RPM and sounds like a jet at higher RPM (from the motor not the exhaust). It never misses or stumbles, it just stops accelerating. I have replaced the cam with a new stock cam. That quieted down and helped it run a bit cooler, but it still has the problems. The dwell is correct and the timing is correct. Both the vacuum advance and centrifugal advance are working. The rear carb is running a bit rich (black plugs on the back three) but the carb is adjusted as lean as I can make it. Below 4k RPM is has good power and the motor is quiet even at full throttle. Any ideas?

When I drive my 72 240z (with the 4 speed) I have an RPM of 2700 for 50 mph. This seems like my car is geared too low. I have been told that I have a 3.36 ratio differential. On a stock 240z what should my RPM be for 50 mph?

I tried the carb cleaner, but once the mist hit the hot exhaust, I had a white cloud of steaming carb cleaner. It did not ignite. Is there a way to do this safely? As far as the float goes, I tries 10mm and 14mm both acted the same. One place said a 71 is 10mm and all others are 14mm. The car is a 72 but the carbs are from a 71. Which is correct?

I have a 72 240z. I just bought it. I found the carbs would not always turn off the choke. I bought two used carbs on ebay, rebuilt them and put them on the car. I adjusted the jets to 2 and 1/2 turns out. The car would not start. I looked at the old carbs and found the rear carb was set to 6 turns out. So I set my rear card to 5 turns out and the front to three turns. Then the car started and ran well. I still have to balance the carbs and tune the carbs. Also my idle is around 1000 and it is set as low as it will go. Is this normal? Do I have a vacuum leak? How do I track this down?