[Adam_G]

Hey all:

Wanted to see if maybe someone had an idea on this. I left my 1960 falcon sitting for a week or two, and it suddenly developed a problem where it dies at idle. Since it was sudden, I figured it would be simple.

This car has run like a top for many many years. I figured it was the carb, so I've rebuilt the 1904 about 5 times now. Last round I had it ultrasonically cleaned.

I have checked every possible vacuum leak source - I bypassed the vacuum advance and the wipers. Still won't idle unless I the choke is on.

I did a smoke test and starter fluid test all over, but I couldn't find anything at all - seemed tight and no smoke/rpm revs with the starter fluid.

Anything else I might check before I take it in? Like, some other place it's gulping air from? I'm stumped. It'll run at speed all day...

Adam.

 

[redrag]

increase the idle mix to see if prob goes away

 

[Adam_G]

increase the idle mix to see if prob goes away

Thanks - def not changing anything. It's running so lean that I have to choke it about 1/2 way to get it to run. Idle screw makes no difference. Note, this change happened overnight - so something broke, or got stuck suddenly. Less likely a setting. You know?

 

[Action]

Welcome to the FFO!

Check and make sure the float level is set correctly.

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[ms fowler]

Did you just add gasoline to the tank?
Before making any changes, i would pull the gas line off the carb inlet and crank the engine while catching the gas in a clear container. Look for water or dirt in that gas.
Also look at all the vacuum lines. Pull them of their connections and examine if the ends are cracked and split, or if they are loose.
If all of that looks good, I would do a cylinder balance test--Re-connect the gas line and all the vacuum lines and get the engine running up to temperature. Then remove one spark plug wire at a time from the distributor cap and note how that affects the engine. You could short out each wire, or use a pair of insulated pliers to remove the wire from the spark plug end. Each cylinder should have about the same affect. If one cylinder has no affect, then you have found the bad cylinder. Check that spark plug. I hope you don't have to go deeper than that.

 

[2thpic]

^^^^ WHAT HE SAID
Also on the float getting stuck could be the problem as well. I have had that happen before.
All this new gas can be bad on our old cars.
If you use the basic gas at the pumps with ethanol fuel, it bad on these old carbs.
I would not think timing but if it's an old timing chain and wore out...wouldn't hurt to check the timing.
Also from experience on the carb, I had rebuilt mine 2 or 3 times and I found (3) screws that where just about striped out and they would not tighten up all the way and they created some vacuum leaks. I ended up buying a new carb.

 

[Adam_G]

Great ideas guys - thank you. Much appreciated.

I have a glass bowl on the carb, so I can see the level and the fuel - it's all right, and I can see the fuel feeding into the bowl just fine. It's sitting about about 60-70% full, which seems about right. I can pinch my fuel hose that feeds the pump as a sort of regulator to adjust the amount - it seems to be happy where it is naturally.

I think I had a lower fuel level when this problem occurred, and I filled it thinking it might have been bad gas. So it has relatively fresh gas - I have historically added lead substitute to E10 and it's been ok for about 4-5 years until now. Fuel filter looked clean as did the carb when I pulled it apart. No real gunk.

I think the spark plug / balance test is an interesting idea. I'd have to get the choke just right and keep it at higher revs but this might uncover something I hadn't thought of. I may go ahead and put new plugs in - I think these are ready for a refresh.

 

[ms fowler]

I remember those glass-fronted float bowls; they do help with diagnosis.
Keep going at a slow, methodical pace--it's not as dramatic a ripping it apart, but it will help you discover the initial cause.
How strong is the spark? You can pull the center wire from the distributor cap and hold it near the block and see how long a spark will jump while cranking the engine--or just opening and closing the ignition point with a screwdriver.

 

[POWERBAND]

The 1904 type front glass bowl carbs - bowl gasket is typically of a rubber and cork formula. I have had continuing problems with the solvent methanol in the modern gas dissolving the rubber in the gasket and causing jet fouling problems. Some vendors sell cardboard/composite gaskets which last longer but still may be affected.

' been trying different gasket treatments to help, interested what you find.

.

have fun

. . ..

 

[Action]

What about a silicone gasket cut out of a sheet?
I hate silicone because of what it did to a vehicle that electronic engine controls. But this application has zero electronics.

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[Action]

Never mind. I researched silicone and it is not good with gasoline

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[63falcondriver]

If the idling issue occurred all at once it's most likely a piece of dirt somewhere in the idle circuit. Sometimes screwing the idle screw all the way in and then backing it out to where it was will solve the problem. (keep count of the turns)

 

[redrag]

back out the idle mix screws a few turns. rev engine up and cover the carb with your hand. this will put a huge vacuum on all the orifices in the carb. sometimes it will wash out the gunk. p.s. take your hand off before the engine dies

 

[ms fowler]

back out the idle mix screws a few turns. rev engine up and cover the carb with your hand. this will put a huge vacuum on all the orifices in the carb. sometimes it will wash out the gunk. p.s. take your hand off before the engine dies

Yes---this may be simple fix. I had forgotten this but it worked in the past.

 

[POWERBAND]

regular RTV is not resistant to most oils and fuels. I've treated the gaskets with resistant sealant/dressing which slows degradation.

Permatex® PermaShield® Fuel Resistant Gasket Dressing & Flange Sealant, 2 OZ – Permatex

www.permatex.com

When I got the '61 the PO had used blue RTV for everything from VC to water pump and anything disassembled. I found blue worms of the stuff in the oil pickup screen , lifter galleys ...

have fun

.

 

[Iowan]

Back in the nineties I bought a low mileage Dodge for the 440 drivetrain it had but I ended up putting a header panel on it doing a little paint work and driving it. 440 mopars are good for baking valve cover gaskets and had been repaired with orange silicone sealer on both valve covers. I pulled the covers and put the proper gaskets in along with keening all the silicone out that I could find. About four months after a big glob of silicone stopped up the relief valve in the oil pump and took out the crankshaft.
That was over thirty years ago and to this day I don't use it....

 

[Iowan]

With the exception of the China rail on my small blocks.

 

[Adam_G]

New plugs didn't change anything. I did find that all the plugs in there were completely black. Running rich make sense?

Haven't measured compression yet.

I mentioned I isolated all vacuum sources with silicon plugs :vacuum advance and wiper hoses are all plugged up. I previously smoke tested for leak and found nothing under the hood. So, is there any where else I might find a vacuum leak if not these 3 places? I have no brake booster.

Though I've rebuild this carb 5 times, no kidding, I must be missing something. When it's idling there is fuel coming in under the choke plate - which is above the throttle plate in a sort of spurt/splash. Seems like it's coming in through the spindle. I'll shoot a video of it running. That seems wrong, and that there should just be fuel coming in below the throttle plate, right?

Seems like a new carb would answer the question - is it the carb?

 

[redrag]

it is a carb problem. iremember now there is a spacer on the float shaft that keeps the float on the needle. it goes on between the bowl and float.

 

[Action]

Other places for a vacuum leak would be intake gasket and carb/sapcer to intake gasket(s).

Upon cold start the choke plate should open right away. (Even while cranking) With a small gap between the choke plate and the carb body to allow some air flow. That would be one of the adjustments to make when rebuilding the carb.
If the choke plate stays closed all the way, there is not enough air flowing to support combustion.

Fuel will come out of the area that you posted. Not really a spurt. And that sounds like you are running rich.
REDrag is on the money at directing you to look at float for this.

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