340 runninng lean and overheating

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Speaking of coolant... the OP could still have air in the cooling system. That can make the engine run hot and it will boil more easily. Park the car with the radiator high and refill. It may take a few heat cycles to work all of the air out to the top of the radiator.

OP, do you have an overflow tank on the radiator? Or just a drain hose from the radiator cap?

And, be aware that with headers, they directly radiate a lot more heat into the engine compartment than stock cast iron manifolds.
 
So instead of replying to all you nice people, I just want to give an update.

Started the engine sine I was going to upload a short clip. Fiddled a little with the distributor cap and fired it up. Sounds completly different. No idea why, but if I where to guess, the cap could not have been fitted properly before, og some **** fuel finally ran out, and the good followed??
Also, my sparkplugs are now om the black side.

Will have a test drive tomorrow followed by timing checks:)

Regarding overheating and air om the system, I believe that this i correct. Did not think of that

Anyway, I will upload the clip regardless
 
On the coolant.... if there is no overflow container, then you cannot fill the radiator higher than about 30-35 mm below the radiator cap. If you do then the hot coolant will push out and onto the ground to create such an air gap at the top of the radiator.

That year of car looks like it should have an overflow tank but I do not know if it is there.
 
Don't know if your car came with a reservoir tank or not. Under your radiator cap there will be a rubber hose. It will go down the side of the radiator or it will go into a white/clear plastic tank. If it goes into a tank, the cap is special, and the radiator gets filled fully. If you don't have a tank, leave an inch of air space above the coolant. There was a flat plate under the rad. cap that showed the cold coolant level.

When changing coolant, fill the coolant leaving a 1'' space, run the engine till the thermostat opens. The coolant level will suddenly drop. Add coolant as above.
 
On the coolant.... if there is no overflow container, then you cannot fill the radiator higher than about 30-35 mm below the radiator cap. If you do then the hot coolant will push out and onto the ground to create such an air gap at the top of the radiator.

That year of car looks like it should have an overflow tank but I do not know if it is there.

Don't know if your car came with a reservoir tank or not. Under your radiator cap there will be a rubber hose. It will go down the side of the radiator or it will go into a white/clear plastic tank. If it goes into a tank, the cap is special, and the radiator gets filled fully. If you don't have a tank, leave an inch of air space above the coolant. There was a flat plate under the rad. cap that showed the cold coolant level.

When changing coolant, fill the coolant leaving a 1'' space, run the engine till the thermostat opens. The coolant level will suddenly drop. Add coolant as above.

Thank you both, good tips :)
Will air out the radiator and the servo later today.
As for why my car does not have a overflow container, which it dosen`t, I believe the car originally had a slant 6 and has been later converted to a 340. Not 100% sure of this but it seems likely right?
 
My 1970 Swinger 340 did not have a overflow system. On trackday I was told to just insert the puke-hose into a popcan ziptied in place, and they would let me onto the track.This was a basic puke-tank system.

By 1973 it had morphed into a coolant recovery system, where the fluid gets sucked back into the rad as the coolant in the engine cools down. This is a smart deal, because the rad is always full, and therefore the engine is too ......... until you forget to check it one day. It's like having an elf under the hood, topping up your rad every night, until the well goes dry.

IDK about the intervening years.
 
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