[Andy Burke (Slump)]

I've been told this is a carb. problem. What would be a good replacement for a 318?

[Hans (72challenger)]

Is it that the rpm's drop slowly when the engine runs idle? But when you brake AND accelarate a little it keeps running? If so, I had this too with mine edelbrock carb, a friend of me re-adjusted both float levers (or something like that) inside the carb and now it's running again great! Could save you the money of buying a new carb.

[Dave-R (Roppa440)]

Unless a major part of the carb is physically damaged then any carb problem is just a matter of tuning or gaskets. You don't need a new carb unless you are increasing the performance in other ways. You certainly do not need to replace it just for a fuel leak.

If you have never worked on a carb before now is the time to roll your sleeves up and teach yourself!

[Andy Burke (Slump)]

The problem is that it won't start when the engine is hot. The carb I have now is the old carter quadra-jet with the plastic casing.

[Dave-R (Roppa440)]

OK. That is not the standard carb for this engine so I had not considered this.

You either have a fuel leak into the intake manifold causing it to flood as you suggest or your fuel line is getting hot and the fuel is boiling in the line or filter - causing vapour lock.

Fuel leaks in a Carter are rare.
It is possible that someone in the past has damaged the plastic fuel bowl by forgetting to take the center screw out when trying to lever the top off. (Hello Hugh!)

Try this.
When it engine is full temp. Switch off and get your head over the carb. Have someone SLOWLY open the carb and hold it open. Don't let the throttle move arount once open. With a torch and a screwdriver to open any vacuum operated bits out the way, have a good look right down through the carb and LISTEN!

When you opened the carb some fuel will have squirted into the intake. This will evaporate fairly quickly. Look for any signs of fuel dripping. If there is a leak bad enough to stop your car from starting it should be evident. The floats in the fuel bowl have to be set right so if there is a leak try adjusting those first. If the fuel bowl is cracked then your best bet is a new one. They now make new Thermoquads.

But listen for any signs of boiling. Listen to the carb and the fuel lines/filter. Any bubbling in the carb or lines means vapour lock. You will need to re-route or insulate your fuel line if this is the case.

[Tedd Lister (Teddl)]

I recently rebuilt a Carter thermoquad and read quite a bit about it. One failing they had involves the seal between the center casing and the air horn. There are two gaskets there that can leak gas straight into the manifold, so I am told. Here a couple links to get you started.

http://www.offroadexchange.com/projects/CrtRbld.htm

http://kenalbin.com/tech/vaanth_tq.txt

If you decide to swap the carb, find out if you have a spreadbore or squarebore manifold. The squarebore has larger secondary holes while the square while be symmetric. The carter TQ is a spreadbore but someone might have used an adapter plate to fit it to a squarebore. There are many more choices for a squarebore carb, an Edelbrock performer 625 cfm would be inexpensive and easy to find parts for. You can use a squarebore on a speadbore manifold using the adapter, but I hear it is not ideal. Likely will not matter too much on a 318 though.
Tedd