7tooZ

Hope this helps

That is the case for these cars in Washington State. Plus I have been told that in those days not all manufactures produced what we referred to as MSO, the manufacturer’s statement of origin.

Just take al9ng your smart phone. Tune it to “Waze.com”. It will give you your GPS speed.

My calculation is that in fourth gear and 4500 RPM you should get 84 MPH. That is dashed on the stock tire diameter. Ps did you install the white colored speedometer gear?

Well it looks like this trans pretty much a standard 78 280z. Still acceptable for the price. Next step is to put it in and see what happens. Probably wait for fall so I pull off my stock down pipe customized to connect to the Zstory exhaust and have it ceramic coat it.

@siteunseen so I I am still learning things. I was advised that lifting the pin should not change the idle but that it is an indication of the need to further adjust the mixture. maybe @Terrapin Z can weigh in here. I know he has more SU experience is than I do.

Sorry if I made you make big changes. From your above comments it sounds like you are really close. It is hard to know how bad the “stumble” is from here. I went through what sounded like similar issues with mine. Once I thought I had the mixture close I started making small adjustments such as move the timing and then adjust the idle speed screw. Drive the car. The more you drive the more you will understand small changes. Even when I thought I had it right I learned last year when I had it on a dyno it was it lean. Even then it was only about a quarter turn rich to improve it.

Yes. Someone suggested put on an old clutch disc for a more accurate count and turn 20 times.

So go back to your original settings when you started this post. Set timing to 7 and if idle drops to low just turn the idle screw to increase idle. Does it still stumble? Your idle mixture should be around the 2.5 turn mark. I found I needed to drive the car to really find what would take out stumble.

Picked one up today. Haven't verified the gear ratio yet. I need someone the help count turns, a mirror doesn't work. It looks good from what I can tell and is suppose to have new bearings and seal and internals are suppose to be excellent. As the leader of our country would say "We'll see", But it's a gamble though.

Can the gear ratio be calculated by turning the tail shaft and counting the input shaft?

@Dave WM @zedhead thanks for the input. Heading out to look at it.

If you were considering buying a used 5 spd what would you look for when inspecting?

If you back off the timing say to 7 BTDC does the idle drop? If you advance to timing does the idle change? or There is a push pin on the bottom of the carb that lifts the piston. Does the idle change?