My 56 Bird has been sitting around for awhile (over a year partly due to the bug).    The last time I started it I had put in a new (to me) distributor but never put a timing light on it..  Also had the fuel pump go bad.

Got it going a couple of days ago.  Started good, idled good.  Disconnected the vacuum to the distributor, plugged the line coming out of the carb, set up the light.  Started ok, but wouldn't idle.  Reconnected the vacuum, started good, idled good.  Can't understand what is the problem.  Don't know what to try, seems pretty simple but can't figure it out.  To me it sounds like a vacuum problem, but I plugged the hose going to the carb.  Checked my other vacuum lines and don't see anything wrong

56 Bird, 312, newer engine (very few miles), C4 trans. 57 Bird distributor.  teapot carb modified by Ted for the 57 distributor (Ran the car with another, non Bird distributor and it ran ok, I assume  I put a timing light on it then, disconnecting the vacuum as usual.  No problem at that time I can remember.)  Carb was on the old engine and ran good.  Distributor was not the one I had on the old engine.  Heater and wipers are all mechanical (no vacuum)

Any ideas?


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

I’ll take a stab at this.  I’m assuming that the distributor vacuum is hooked up to the added port on the Teapot carb.  If that’s the case and the engine wants to die when unhooking the vacuum advance hose, then this sounds like too much throttle opening at idle.  When all is good with the world, the ignition timing at idle is expected to be the same with the distributor vacuum hooked up and unhooked.   That’s assuming that the fast idle for the choke is not activated which will move the throttle blades above the ported vacuum hole in the carburetor.  With the choke deactivated or fully open, the primary throttle blades are expected to be sitting below the hole supplying vacuum to the distributor thus shutting off the feed to the distributor until the idle is kicked up just enough to put those blades above that same hole.  I’ll suggest putting a timing light on the engine and verify the ignition timing at idle with the distributor vacuum hose hooked up and unhooked.

Lorena, Texas (South of Waco)

Ted - did check the timing with the hose connected which showed too much initial timing but was hesitant to change it because the vacuum was connected and may have had an impact on the reading .  RPM was about 600  (Tbird tach).  but since  it won't idle with the vacuum disconnected how can I check it?  Working alone.

I should add that the engine was not fully warmed up.  Any chance that it could be a distributor problem?


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

When you disconnect the vacuum line, you need to plug it with something to stop the vacuum leak(phillips screw driver).  The engine goes too lean and cuts off if you don't.  Set the timing at idle with the vacuum line disconnected and plugged.  Check total timing the same way.  (Idle ~12*BTDC total 38*) Then when you plug the vacuum line up, it should still be same idle speed or slightly faster depending on how the vacuum pot is adjusted.  Joe-JDC

JDC

Been my experience also. BUT, why the hell then does the shop manual tell you to unhook the vacuum line when checking initial advance?

6 VOLTS/POS. GRD. NW INDIANA

I've wondered about that, and my opinion is it's kind of a "belt and suspenders" approach to ensuring accuracy at setting the initial timing.

It's true, ordinarily there won't be any vacuum at factory idle, but if the idle RPM for some reason is elevated anything much above OEM specs the vacuum advance will start pulling in quite a lot more ignition advance. This will skew getting an accurate timing adjustment.

In fact, I suspect this is why most people probably prefer a little bit higher idle RPM in general, say 600 to 650 RPM in a manual - the "extra" advance smooths things out a bit. Check it with a timing light and it will be 20 to 25 degrees, something like that.

Paul,
You might try connecting a vacuum gauge with a T connector to the vacuum diaphragm with engine at Idle. Ford specs state that it takes 5 inches of vacuum to start the advance moving on a 312 57 bird. It might reveal something.

My idle is typically higher than factory spec., and unscrewing the frigging vac. line attachment was such a pain, I once cut my steel line and inserted a rubber section so I could just clamp it off with a hemostat.  Since there was never any difference in the advance, I eventually went back to a stock OEM line setup.

6 VOLTS/POS. GRD. NW INDIANA

Hard to say if this is a distributor problem but it's not high on my list right now.  The ignition timing being too far retarded is at the top of my list for now.  That would force the throttle blades to be more 'open' and in turn expose the ported vacuum hole to the lower side of the throttle blades at idle in stead of being on top of the blade.  Rather than disconnect the line with the engine off, then disconnect it with the engine running.  If the engine wants to die, raise the rpm by engaging the choke fast idle cam.  Then do an ignition timing check with a timing light and watch the timing marks as you slowly disengage the choke fast idle cam.  This is expected to bring both the idle and the BTDC timing down but should not be having the engine slow down to the point of shutting down.  Without more information, I’m just grabbing at straws from this end.

And here’s more food for thought.
When everything is right, the distributor vacuum port at the carburetor will not have a vacuum signal present at idle.  While it’s typically recommended to plug that vacuum port at the carburetor when setting the initial timing, it’s usually not necessary as there is no vacuum present at that point at idle on engines in good condition and close to the ideal tuneup.  That lack of vacuum signal is the result of the ported vacuum hole within the carburetor being above the throttle blade at idle.  As soon as the idle is increased, that same ported vacuum hole is now below the throttle blade where the manifold vacuum now produces a vacuum signal for the distributor and advances the ignition timing accordingly.  That vacuum signal diminishes and goes away after the throttle is opened 1/3 and more.  At full throttle, there will also be no vacuum signal present at that the distributor vacuum port.

I was going to add a couple of pictures showing the throttle blade relationship to the ported vacuum hole (also called metered or indirect vacuum hole) but the YBF site on my end is currently having some issues on loading those pictures.  I've given Jim a shout to see if he can sort that picture posting thing out.

Lorena, Texas (South of Waco)

You can also static time the initial advance.(Setting the timing without the engine running.) It is very accurate, just more time consuming than with timing light.
Get the engine on desired point BTDC. Example: 8 degrees BTDC.
Attach a 12v test light to the distributor side of the coil and to a good ground.
Rotate the distributor so that the points are closed and the rotor is approaching  the cylinder it is to fire on. It does not matter if you use 1 or 6 cylinder for this process.
Turn the ignition on. If the points are closed, then the light should be off.
Slowly rotate the distributor the opposite direction to which the rotor turns. The instant the light comes on is when the points open which is also the time when the engine will fire. 
So what ever you have the crank set at BTDC will be your initial timing. 
I do this every time I have a distributor out, and the motor fires straight up. If I check it with a timing light it is always spot on.