Wooops, now I know why it was never brought up, sorry.

Bud in Northern Arizona on route 66 in Winslow (standin' on the corner)

If you're American, buy American

631/2 Galaxie 500XL 406   55 T-Bird

No need to apologize.On any vehicle that does have a vacuum mod valve it is a common item to fail and cause a vacuum leak.The Fordo uses a link from the accelerator linkage to control the  fluid pressure (shift points) in the transmission.

  

This is just a wild guess, but I guess you have tried everything common. Years ago the hose going to the heater control got hard as a rock. Every time I would shift gears, the engine would move and cause a vacuum leak. I didn't figure it out until the first cold spell and I couldn't get any heat. It cost several $5 bills and the embarrassment of seeing tail lights.

Kenneth

Fredricksburg, Texas

Hello Kenneth! I have the other heater type with the 4 hoses and the valve on the firewall with the cappiliary tube.Good suggestion though.

  

I have been following this as well. My 57 bird, with an edelbrock 1405 just started doing this.



I had taken it to shop to have the carb adjusted because it would not start very well and had a lack of power. They adjusted the timing, and carb. Now is starts right up, and runs with power but dies when you put in gear just like your saying...Shop thought the converter might be bad as well but when I spoke to Concours they said very unlikely as they were pretty much tanks regarding construction. He also thought a new carb kit might help. So the problem might not be a carb issue? Not sure if that helps or muddies the water. I was going to try the propane trick but I can see you did that already. Could the resistor from the coil have any affect on this?



Rod

1957 Thunderbird

312

I talked to 2 tranny guys familiar with the Fordo and both said the same thing-not transmission related.Steve(Greenbird56) is helping me to setup the carb and timing better and we are having some success.Much better but still have more "tweeking" to do.One thing that has helped is taking the carb off and closing the primary throttles to where the "transition" slot is visible below the throttle plates as a "square".Once that was adjusted I have been using the seciondary throttle plates to adjust idle speed.If you take a look at your carb below the vacuum control for the secondaries is a threaded hole in the carb base.Its a 8-32 machine thread.If there is allen head screw in there now you can use that to open the plates slighly to set the idle speed.No more gas is added just air.I got an 1 1/2 8-32 machine screw and double nutted the head and added one more to lock the screw against the base once I had the speed set.I can access the screw fron under the carb base.Steve says some cant because of the spacer plate.In that case you have to adjust the screw fom on top-real pain.If you open the primary throttle too far you are adding more circuits than should be in play.I have always thought the speed must set from the primary plates only but this way Steve has explained works.I am also working on the timing.I discovered the vacuum advance is only adding about 4 degrees advance even with 14 inch vacuum.Should be more like 10-12.Also using fulltime vacuum instead of ported so the vacuum advance works right off the bat(gives more idle speed without touching idle speed screws).Going to readjust the vacuum unit to give proper amount of advance.As I said I am still working on this but improvements have been made.Keep you posted.Should mention I have a Holley carb.Dont know if edlebrock is similar.

  

Mark, could the engine be idling on 7 or even 6 cylinders? If so you would still be able to get the engine to idle just fine by raising the idle speed screw (reason for more of the transition slot showing), but when it is put in gear the load would now be spread across fewer cylinders 6 instead of 8 and the engine would die. With the engine idling in neutral and a pair of WELL INSULATED pliers remove one spark plug lead at a time and see if all cylinders cause a similar drop in power. Check only takes a couple minutes and could lend some insight. Mike

1956 Fairlane Victoria (ORREO)

 

Overlooking Beautiful Rimrock AZ

Hi Mike! I did try that.I did notice a real difference in most cylinders except hard to notice on 4 and 8Maybe because they are firing next to each other in firing order.t.I replaced the wire and tried it.Didnt notice much change with wire off.I have an accurate Snap-on dwell tach coming and will be able to tell better.Also replaced the plugs with new ones.All plugs are showing normal color.Timing light on all cylinders shows firing so........

  

Mark, keen to see you sort this problem out, have you tried vacuum gauge on engine? Check reading in nuetral then in gear, seems like low power in back cyls, vac leak? regards bill.

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

I'll welcome a correction by Mark if I mis-state this but what seens to be happening is that the engine is down on torque at low rev's when the auto trans is engaged. That causes a "stall". It is a new rebuild, may have a good bit more internal drag than it had before the refresh. He has tested his spark system several ways - and it is making sparks - but maybe not at the right time.

To build the required torque, the engine needs air - and the 390 CFM carb has very small primaries. So his inital response is the same as the rest of us - turn up the idle screw. As a consequence, the blade is wrongly positioned on the idle transfer slot - she was just about operating on the main jets. Holley has a manual for this carb that suggests opening the secondary butterfly to get additional idle air.

 

This not only works well but beats the daylights out of the old "drill holes in the butterfly" solution. The secondary bores have fixed flow idle weep holes - this outfit just needed some air. Holley has some really poor directions in the manual for setting the idle transfer slot position - so we used the one recommended by BG for the Demons.

This seems to have gotten him some idle control and additional torque (adding air to the existing fuel flow) - but now he has found some discrepencies in the way the vacuum advance pot is behaving. It is very erratic and may have a hole in the diaphragm or something like that. 

 
 Steve Metzger       Tucson, Arizona