Clay,

What is that jagged edge on your butterfly. It looks like you are going to loose half your butterfly.  

Very likely the reason for your rough running.

Cheers

Warren

Grizzly (Aussie Mainline)

Grizzly,



If your speaking of the top photo about in the middle just above the axle for the butterfly; It looks to just be the transition between the dry and the wet portion of the butterfly. I'm getting pretty fast in taking this carburetor off and on. This last time the engine was still running.



This is more evident in this photo.







In the upper left corner is some black (?) that seemed to dislodged itself from where I don't know. Looks like paint from the butterfly, but the butterflies look to be anodized.



Way back in one of my first posts I mentioned a slight miss at rest but in gear. It is still there. I guess one of the future steps would be to check each plug. Still have the Petronix II standing by to go in as well.

pops (AKA) Clay

'56 Thunderbird

Clay,

That's better Odd what a camera can do at times.

Cheers

Warren

Grizzly (Aussie Mainline)

Clay - You are hereby appointed the site carb photographer.....hope we can use these photos for some future advice???? Just need to put some black arrows on the spots we commonly point out....

Do you have a vacuum gauge in your toolbox? I'm curious what the needle is doing when the engine is sitting at loaded (in gear) idle. 

When you check your plugs - set them up at standard gaps if they've been opened (as Pertronix recommends) - Ted has some dyno data that shows that the factory gaps give best power (on a Y-block). 

 
 Steve Metzger       Tucson, Arizona

I have a vacuum gauge. I note that this carburetor does not have a vacuum tube coming out of its base like the last one did. However, there is a block near the back of the manifold that I can adapt some fitting to allow the gauge to be connected there. What kind of readings would you suggest I record when I return home on Friday?

pops (AKA) Clay

'56 Thunderbird

You will want to record reading at idle with motor fully warmed up.Gauge should read 19-21 and steady in a motor in good condition.If its not steady how much does it vary?Whatever variance you note is helpful in diagnosing possible problem.

  

This chart isn't as cool as some that are animated - but it will show you the information available from the vacuum gauge.

http://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.htm

The tube you have disconnected from the fuel pump - direct from the back of the intake manifold - is as good a tap as you will find. Do you have a thermal break isolator under the carb? Drilling a passage - and adding a short piece of brake line tubing with JB weld or epoxy can add an additional manifold vacuum port. They work best when they sample both chambers of the split intake manifold.

 
 Steve Metzger       Tucson, Arizona

TOO HOT!!!









Struck out on getting the Zephyr PCV valve yesterday. Really too hot to work outside anyway. I took a bullet and performed "honey do's" INSIDE where it was cooler. I'll try another supplier for the PCV valve today.

pops (AKA) Clay

'56 Thunderbird

I'm back.....



Three strikes on the 78 Zephyr-Fairmont PCV valve. Went to three different stores and none of them had one.



I did disconnect the vacuum line from the manifold to the fuel pump and looped it back to the other vacuum line to the fuel pump. Then put in a straight fitting in the manifold to accept the vacuum gauge.





Hose/line to fuel pump.







Left hose to power brake, Center hose to fuel pump, Right hose is PCV.







Straight fitting for vacuum gauge. Vacuum lines to fuel pump looped together.





Engine warm, vacuum to carb plugged, brought initial advance down to 10 degrees. Idle speed in neutral = 700



vacuum gauge reads:







700 RPM seems to be as low as I can get the idle.

pops (AKA) Clay

'56 Thunderbird