Flathead won't idle

[Vanspeed]

I have a 48 ford truck on it's way. Guy said just recently it won't idle. He says you have to stay on the gas a bit. What should I look at first? He thinks the carb sucked something up as it was rebuilt and sat for a bit. It has the flathead in it.

[Lanny]

maybe a cracked vacuum hose, or a loose base on carb, or loose intake bolts.

Does it start easily, or does he have to prime it ?










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[Lazy Jake]

Originally Posted by Vanspeed

What should I look at first?

Idle circuit on the Carb. Very easy. It may have a small piece of crud blocking fuel flow.

[Old Henry]

Could also be excessive wear on the carburetor butterfly shaft. I've had air leak in there and prevent idling.

[Walt Dupont--Me.]

Remove the 2 idle air screws, take the air hose and blow into those holes, sometimes a piece of crap will get in the idle system, It won't hurt anything. Walt

[gmc1941]

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Any crap in the fuel tank?

[Mike51Merc]

Pull carb and thoroughly clean it. Drain some gas and smell it--- that distinctive varnish smell is a dead giveaway.

[Ross F-1]

Could also be a bad power valve.

[Gumpy]

Originally Posted by Walt Dupont--Me.

Remove the 2 idle air screws, take the air hose and blow into those holes, sometimes a piece of crap will get in the idle system, It won't hurt anything. Walt

Exactly, this may be your problem..

[Vanspeed]

He told me he does have to prime it if it sits at all. He said it runs like a top but dies if you let your foot off the throttle. He did say the tank was empty. Engine was rebuilt and then the truck sat.

[FlatheadTed]

I am, with Walt try the easy stuff first ,if no go !pull as much of it to bits s possible and blast it out with at least 100 PSI .Ted

[George/Maine]

It could be as simple as the throttle linkage is bent on firewall,
not closing plate all the way. Worst is you have a thumper cam.

[FortyNiner]

Originally Posted by Vanspeed

He told me he does have to prime it if it sits at all.

This sounds like part of your issue. So the bowl doesn't hold gas?

[tubman]

Sounds like a leaking powervalve to me as well; I have run across several mis-fitting power valves in my travails.

[Vanspeed]

He said it used to idle very nicely and this just started happening. I will take a look at the carb and throttle linkage.

[FortyNiner]

Looking at the linkage is fine. BUT, the tell in your comments is the need to prime for starting. Something is causing the bowl to drain - most typically, the power valve is the issue. Best bet is to remove the carb to clean it and check the valve seal.

[FlatheadTed]

I know on a Stromberg the power valve is below the out lets so drain down doesn't exist ,to slow carb evaporation ,pull the choke out to seal off the top after shutting down .

[Vanspeed]

No choke is hooked up at the moment. Would a bad powervalve not allow it to idle? I have had cars leak down before but after it starts and the fuel pump starts working it runs fine.

[Binx]

In your first post you said you "have a 48 ford truck on it's way". Has it arrived or are we doing third person troubleshooting? That would be kind of theoretical troubleshooting.

Lonnie

[Mike B]

Originally Posted by Binx

In your first post you said you "have a 48 ford truck on it's way". Has it arrived or are we doing third person troubleshooting? That would be kind of theoretical troubleshooting.

Lonnie

Was thinking the same thing...lot's of good suggestions though, but...