If you have the distributor hooked to ported vacuum, the idle speed may be low enough that you lose the signal when the transmission pulls the RPM down. In gear. Make sure this 12 degrees is with the vacuum disconected.

Frank/Rebop

Bristol, In ( by Elkhart) 

Try the check valve on the power brake booster,maybe there is a leak?

55 fairlane gasser 312 /c4, 57 f100 292/c4, 52 mainline gasser 302/t10 4speed

How old is the fuel?  Does the exhaust smell ‘fuel rich’ at idle?  Can the engine be killed by screwing the idle mixture screws in all the way?  Are the screws that attach the baseplate of the carb to the main body tight?  What’s the list number on the carburetor?

 

What distributor?  Points or electronic ignition?  If points, what point gap?  Ported (timed) vacuum to the distributor or full vacuum?  Is the ignition being timed with the distributor vacuum hose hooked up or unhooked and plugged.  Power brakes?  Where is the vacuum reading being taken?  Is the vacuum reading steady?  What’s the vacuum reading of the engine when in drive?  What year transmission?  Does the transmission have a modulator valve?  What valve lash setting is being used?

Lorena, Texas (South of Waco)

Faulty torque converter in the transmission ?

 Seppo from Järvenpää, Finland
www.hollowheads.net (just click the hole in the head to proceed)

Hello Ted!  Thanks for having a look at my problem.I spent a couple of hours today checking some things.I pulled each plug wire with motor running.All cylinders slowed the RPM when wire removed.Some cylinders seemed more affected and #4 didnt really notice a difference.Ran a separate new wire and changed plug to a known good one.The plug is firing just doesnt seem to make much difference in motor running.Pulled the valve cover and both valves are operating.I dont have a compreesion gauge but used my finger in the hole and there is a good blast of compression.I have to assume that cylinder is working.All plugs are dry and a nice tan color.100 miles on motor.Fuel is 1/2 stale and half fresh.Not smelling rich at tailpipe.Mixture screws will kill motor and seem to work fine.Its a 8007-0 390 cfm.Late distributor with Accell conversion.Ported carb vacuum for distributor.Vacuum line disconnected.Power brake check valve is working.Plugged it and it made no difference just to be sure.Vacuum reading is steady 18 at full time port in base of carb.I turned timing down to 6 BTDC from 12.No difference.Its hard to get a vacuum reading in drive because it just basically quits unless I hold the gas down with the brake. This is the original Fordo.The only other thought I had is the convertor sat empty all winter but the trans shifts fine so I dont know if that could still be the problem.Any suggestions appreciated.It starts fine and runs great and sounds good as long as its in neutral.Valve lash is set at .019 cold and all valves are fully closing.

  

Assuming this problem is not related to the torque converter, the top item that comes to mind based on what you’ve said so far is to raise the carb float level and see if that helps.  Secondary float level is also important as there is a fixed idle circuit on the secondary side of the carb and a low float level there can affect that particular circuit.  If you have the carburetor off, then make sure the base plate itself is tight to the main body.  While looking at the carb, take some carb cleaner and high pressure clean the small air bleeds on both the primary and secondary side of the carb.  Although some of the other symptoms are not pointing to it, I’ll suggest checking that the fuel discharge nozzles sitting within the venturi centers are physically tight to the carb body.  Just take a finger and see if you can get any 'wiggle' out of them.

Lorena, Texas (South of Waco)

Hi Ted  I did a little more today.Checked fuel levels.I set them to where Holley recomends.Dry set primary  float  to 7/32 inverted.Secondary to where fuel is just dribbling out the site plug.Blew out air bleeds etc.Tightened carb screws(not much).Regapped plugs to .032.With a little fiddling it will idle in drive(rough).The vacuum drops from 18 in neutral to 13 in drive.The idle speed  is at the point where the ported vacuum is exposed and advances the timing.Reset timing to 12 BTDC.I dont think there is a problem with the convertor.Is this possibly an ignition problem(weak coil maybe?)In neutral it runs fine.In drive it just wont run worth****.Appreciate your help.Thanks Mark

  

Did some more today.Used a propane torch to check for leaks.Nothing.Changed the coil.No better.Just refuses to idle in drive.How would I know if the convertor is the problem?What would have happened over the winter sitting empty?Running out of ideas on what is wrong?Anybody have any input?Thanks

  

I just reread your posts and it looks as if the car runs fine in drive under power or WOT, but it just won't idle worth junk, right?

The idle carb passages being blocked in some way gets my vote. In N with no load, there is enough fuel (especially being able to manipulate the idle set screws as needed), but under load, not enough fuel can pass through those idle passages to give enough "juice" to the motor.

Dan

Is there any way you have another Y blocker in the area with which you could put some heads together, or maybe borrow a buddy's carb to see if it is indeed the problem?

Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

Mark.........Does it die instantly as if you had turned off the key or does it do a slower death as if it's out of fuel?

 

Paul,

Boonville,MO