Hi All, We have a 72 comet, 250 six, in Southern California. The car has a Carter one barrel RBS carb, just rebuilt. After it warms up and is shut down for a few minutes, it is very hard starting. There is a smell of gas and the idle is rough, also. I think that the fuel is percolating in the float bowl. We have double checked the float lavel, replaced the fuel filter, cleaned the carb again, etc. Any ideas? Thanks, karguyz
yea check your fuel line, might be running next to something hot. I think I had the same problem and it was called vapor lock or something. My problem was apparently the fuel line running too close to the manifold, it was a while ago though.
Thanks for the suggestions. 1. This carb has a remote float bowl. It is surrounded all around by air and is connected just in one spot to the main carb body. Might look into making up a carb spacer out of bakelite or similar. 2. The fuel line is not touching anythinf from the pump to the carb. There is no problem while the engine is running, like vapor lock. 3. The Comet is sort of an upscale Maverick and has more insulation. There was a thick blanket that covered the whole underside of the hood. The air cleaner actually made an impression on the insulation, which shows how close the hood fits. We just removed this blanket. My theory is that the heat under the hood is not able to radiate out and gets trapped when the car is parked. This car has a big a/c compressor just in front of the carb which must block some of the airflow from the fan. I'll let you know when we do a test drive if this helped any. karguyz
The RBS does not have a remote fuel bowl...it's a removable fuel bowl. Do you have the heat shield under the carburetor?
After you shut it off get a light and have a look down the carb to see if fuel is dribbling out the venturi area.
Yes, I was able to see fuel dribbling inside the carb. That's when I pulled the carb and cleaned it out, replaced the fuel filter. No, it doesn't have that aluminum heat sink, or the small brown/orange spacer between the heat sink and the carb. The carb to manifold adapter is cast iron, with a hole in the side for the pcv valve hose. There is a log manifold adapter connected to the intake manifold below tha carb. It has a threaded plug on the front. I think I can replace the threaded plug with an adapter with a nipple on it to match the pcv hose. Then make up another carb to intake manifold adapter out of something less heat conducting. Removing the hood insulation seemed to help some. Thanks for the tips. Karguyz
My intake to carb adapter is aluminum...it has a paper gasket between the intake and adapter. I'm sure the heat shield is important or Ford wouldn't have spent the money making them and then pay somebody to put them on the car.
I bought a new 1981 Mustang with a 200 cid automatic with air and P/S. although it was an excellent car it to was hard to start when the engine was hot especially in warm weather. The dealership found no prolbems and told me the fuel gets hot to boiling point that causes this prolbem. They said this was a typical 6 cyl prolbem and I should let the engine cool a bit before restarting. I used to hold the gas petal to the floor until the engine fired. After a valve job and some other engine repairs thourgh the years it still was hard to start when hot. This car lasted 10 years and was driven 151,000 miles before it was rear ended and scraped.
Jeff, That last picture you posted shows the hex shaped manifold I was referring to, lower left of photo. See the plug in front? I intend to replace it with a fuel hose fitting to fit the pcv line. I'm not surprised there is a hot start problem with this car. The extra height of the long stroke motor and the low hood line make for minimal clearance. If it was a Maverick I would think of punching some louvers in the hood but the Comet design wouldn't look right with holes in the hood. Karguyz
This happens to my Comet. I find that if i let it sit a few minutes I can start it fine. But yeah, I get the strong odor of gas and the bad idling when shutting it down in Park. My dad and i tried adjusting the timing on the distributor ( I think, he knows cars and it's mostly over my head , though I'm learning ) but it only made it less worse.
It ain't going to do anything but get worse. Ethanol in fuel now causes lower boiling point. Winter blended fuel even lower (as low as 75-80 deg F). I deal with it daily especially on V-twin engines where the carbs are mounted in the valley. Air cooled ones are 10 times worse. 10 years ago E-10 was unheard of for the most part. Now straight gas is unheard of. I believe too that our government has also recently allowed fuel companies to up the amount of ethanol to 15% before the "contains ethanol" sticker is added to the pump. Ya'll might want to check that out-my source is less than reliable.
