Just saw you picture from a week ago, here is a picture of my stock 76 280 in that area.

Hope this helps.

Took advantage of the 3 day weekend and made some more progress on the Z. Got to clutch issue straighten out. The aftermarket rod on the Clutch MC I installed was too short. I extended it about an inch and that magically fixed all my clutch issues. Got to take the Z out for some break in miles. So far so good, the car rides very nice and cruises great at 70. The engine is running lean so I'm going to adjust the AFM to see if I can richen it up.

My next major project is the headlights. At first only the right on was working. I unplugged the left one, cleaned the ground, re installed it and now neither work! Except the right high beam. I'm getting power at the fuse, so it seems like I have an electrical gremlin somewhere. There's a car show Friday night I'd like to take it to, but only if I can get the headlights working. Right now I'm daylight restricted.

Here's a video of me pulling it out of the garage for the first time and a few glamour shots I took while breaking it in.

The engine is running lean so I'm going to adjust the AFM to see if I can richen it up.

Many of us have had better luck with a potentiometer on the coolant temperature circuit to add resistance, to fix a lean problem. Messing with the AFM spring changes the slope of the enrichment curve, richer at the bottom not so much at the top, adding potentiometer resistance just moves the whole thing up. Richer everywhere. Plus, if you mount it in the cabin, you can tune on the fly.

Many of us have had better luck with a potentiometer on the coolant temperature circuit to add resistance, to fix a lean problem. Messing with the AFM spring changes the slope of the enrichment curve, richer at the bottom not so much at the top, adding potentiometer resistance just moves the whole thing up. Richer everywhere. Plus, if you mount it in the cabin, you can tune on the fly.

Very interesting. I've seen others reference potentiometers, but didn't exactly know what they were used for. I'm looking at the Atlantic Z site now and reading up on it. I ordered a 1k adjustable potentiometer as he has on the site. It will be here tomorrow. As far as wiring it, I'm a little confused. I get that it wires into the temp sensor, but that's about all I'm understanding. Could you further clarify how to wire it inline with the temp sensor? Thanks!

The atlanticz page shows the coolant sensor with both bullet ends disconnected, for demonstration, so is a little confusing. But you only need to break open one connection, and insert the potentiometer in-line. It can be before or after the sensor. All you're doing is adding resistance to the wire that starts at Pin 13 on the ECU and goes to ground. The ECU will think that the engine is colder than it is and add fuel. The sensor's resistance increases as temperature drops. It won't take much, I hope that you got a taper style potentiometer, they have a finer touch on the ends of their adjustment.

I ran a few feet of wire from the connection on the engine harness and mounted the pot under the driver's side dash. In the engine bay is fine if you don't plan to mess with it much. Make sure it doesn't get too hot, it's probably not designed for engine bay temperatures.

I added a picture from the Fuel Injection Book, illustrating the circuit and the bullet connections.

I made mine with enough cable to tweak it in the cabin until it seemed right. After that I mounted it along the fuel rail. This pod is a 5k ohm unit I had a 20k ohm, but it was a little course and harder to fine tune.

Chas

How are you guys determining what size potentiometer to use? Is it a trial and error thing? It seems the bigger you go, the harder it would be to fine tune. I got a 1k, I'm going to install it today and max it out. See if I notice a difference from there.

Start at zero and work up. The pot is actually a good theft-prevention device. Just crank it up and you'll flood the engine. I have a 5K from Radio Shack and I barely use 5 degrees of knob rotation.

Took advantage of the 3 day weekend and made some more progress on the Z. Got to clutch issue straighten out. The aftermarket rod on the Clutch MC I installed was too short. I extended it about an inch and that magically fixed all my clutch issues. Got to take the Z out for some break in miles. So far so good, the car rides very nice and cruises great at 70. The engine is running lean so I'm going to adjust the AFM to see if I can richen it up.

My next major project is the headlights. At first only the right on was working. I unplugged the left one, cleaned the ground, re installed it and now neither work! Except the right high beam. I'm getting power at the fuse, so it seems like I have an electrical gremlin somewhere. There's a car show Friday night I'd like to take it to, but only if I can get the headlights working. Right now I'm daylight restricted.

Here's a video of me pulling it out of the garage for the first time and a few glamour shots I took while breaking it in.

[ATTACH=CONFIG]71747[/ATTACH]

[ATTACH=CONFIG]71748[/ATTACH]

[ATTACH=CONFIG]71749[/ATTACH]

[ATTACH=CONFIG]71750[/ATTACH]

Beautiful Car! I recognized it from instagram . My 280 arrives on friday.

How are you guys determining what size potentiometer to use? Is it a trial and error thing? It seems the bigger you go, the harder it would be to fine tune. I got a 1k, I'm going to install it today and max it out. See if I notice a difference from there.

I used a 2k ohm pod from Alpha p/n; B2K. Its adjusted to about 1000ohms.

RV16AF-10-15R1-B2K Alpha (Taiwan) | Mouser

Chas

I installed a 1k yesterday and have it turned up about 3/4. Haven't pulled the plugs yet but there's a huge improvement. The car isn't bogging down any, the overall smoothness of the engine is much better.

Hey guys,

I'm about to start profiling weber's a/f ratio's vs configuration changes. I'll try to do the same for EFI systems this summer and measure what the A/F ratio changes for teeth changes of AFM and resistor changes at the temp sensor as well as idle and WOT enrichment. May even pull out the scope and measure injector pulse width changes.