Flathead won't idle
 

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.

Re: Flathead won't idle
 

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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Re: Flathead won't idle
 

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

Re: Flathead won't idle
 

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

Re: Flathead won't idle
 

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

Re: Flathead won't idle
 

Any crap in the fuel tank?

Re: Flathead won't idle
 

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

Re: Flathead won't idle
 

Could also be a bad power valve.

Re: Flathead won't idle
 

Exactly, this may be your problem..

Re: Flathead won't idle
 

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.

Re: Flathead won't idle
 

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

Re: Flathead won't idle
 

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.

Re: Flathead won't idle
 

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

Re: Flathead won't idle
 

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

Re: Flathead won't idle
 

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

Re: Flathead won't idle
 

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.

Re: Flathead won't idle
 

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 .

Re: Flathead won't idle
 

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.

Re: Flathead won't idle
 

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

Re: Flathead won't idle
 

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