I recently had new shafts installed by Joe Curto and after installing the carbs on the car it ran fine. I decided to try and sync them and give them a tune according to the manual. While making adjustments the car died. No it will start only when cold and as soon as the AED shuts off the motor dies and won't restart. I thought it was flooding but pulled the plugs and they are dry. I checked the floats and they are fine and are properly adjusted. I did rebuild the carbs before sending the throttle bodies to Joe for new shafts and bushings. Car has been running fine until now.

Any ides?

 

Rather than flooding it sounds like the carbs are running too weak. Enough fuel whilst the AED is on but when AED switches off not enough fuel.

A good way to check this is get some "easy start" and spray it into the mouth of the carbs as you try to start the car with the AED disconnected. If it fires up you have lack of fuel.
You say there is fuel in the float chambers but this I assume is whilst the AED is open and the engine running and checked after the engine has stopped when the AED switches off. Problem with this is there might not be enough fuel in the float chambers for the carbs so try starting the car on the AED then switch it off at the ignition before the engine stops, cutting off fuel pumps, then look again. If the engine stops and the fuel pumps continue they could be slowly refilling before you open the tops to have a look. Float levels are notoriously difficult to get right. One of the problems being you cannot see what the level is with the top of the float chamber on. The AED draws its fuel from the front float chamber which might be working or filling correctly but the back float chamber might be empty and the engine will really struggle to keep running with just one carb functioning correctly.

Once the fuel float level has been established as correct and the engine still does not run try opening the slow running and the fuel mixture screws beyond the recommended setting in the book. The book says 2.5 turns on the mixture screw and 2 turns for the slow running so wind them both out 3.5 of even 4 and see what happens.

 

Start simple- did you simply get too low on fuel? When mine gets Just low enough, it will start and run for a few seconds then die. It will do this several times, enough to make me think there really is a problem. Can you hear the pump running? And if you have a glass bowl filter can you see gas in it?
Just my Sunday morning thoughts......

 

IIRC, the choking mechanism (AED) turns off immediately (a bit of a flaw in its design, IMO) when the coolant reaches a pre-determined temperature. the temperature is adjustable. if anything has been changed on the AED, that may be the problem.

 

Since the carbs worked fine after the rebuild and with the new shafts and bushings from Cuerto, then I think that you must have mistakenly leaned the fuel mixture too much while trying for the perfect "fine tuning". ? Nothing else makes sense - assuming that you have fuel getting to the fuel bowls. I would just get out your screwdriver and enrich the mixture control (turn clockwise - you may have turned the wrong way before ? ) on both carbs at least 1 full turn. Good Luck !
Schmitty

 

What Schmitty said, and the cars mixture should only be tuned after the AED is fully off and the engine has reached it operating temperature.
When the cars mixture is set, this must not be touched again.
If the car won't start from cold, then the AED needs tuning, either leaned out or made rich.

 

Yes, my bad. Leaned it so much the jets were completely closed. Runs now and better also.

Thanks for all the responses. Learned a good lesson though

 

For tuning the Carbs I have two Gunson colour tune kits. Basically a couple of glass spark plugs that allow you to see the colour of the spark whilst the engine is running. I plug one in cylinder 1 and the other in cylinder 6 the I can adjust the mixture whilst the engine is running to get the balance right.
The colour tune needs to be used as a package with a compression tester, setting the timing correctly, correctly balancing the butter flies on the carbs, flout levels set correctly.

 

I use one of the wideband oxygen sensors with an air-fuel ratio gauge, it provides a very accurate way of measuring the air-fuel ratio. It's very useful because you can monitor as you drive, so useful for determining if the acceleration enrichment is correct or not. I have fine tuned the weight of oil in the carb dampers to correct for a lean condition under acceleration. The jet position stayed the same as under cruise, but with a sharp throttle input it went quite lean and stumbled. A heavier oil and the car pulled strongly with no stumble.

In theory, tuning the carbs at idle should result in the correct mixture across the rev band, but I have found that isn't always the case. The ways of measuring exhaust gases are far more accurate today than when the needles were developed in the 1950's. I have done spreadsheets to determine where I either needed to add or remove fuel across the rev band and ordered different needles than the recommended ones. In particular, I found the needle that Burlen supplies for the V12 E Type SU conversion was way out.

 

any recommendation on which wideband sensor to use ? does it use a wire from the exhaust to the dial or is it wireless ? thanks ! I have used the Colortune method , but found I was running too lean after normal driving conditions...
Schmitty

 

I use the AEM kit: https://www.aemelectronics.com/produ.../parts/30-4110

I had the Innovate Motorsports one, but it seemed to need constant calibrations and wasn't very accurate. The AEM one is rock solid. However, I do use the Innovate tailpipe clamp, so I don't have to weld a bung into the exhaust, I can move it from car to car, or bank to bank.
Clamp: https://www.innovatemotorsports.com/...ust-clamp.html