[Tom R]

Hi,
I have a problem with several carburators that are mounted on three different cars. I'll use the Chevelle for an example, but the symptoms are identical on my 65 Mustang and 71 Bronco.

The Chevelle is a 1967 with a 327. The problem is a leaking Edelbrock "performer" Q-Jet replacement. Here is what it does:

Between 5 and 15 minutes after shutting down a warm engine you hear a strange percolating noise from the carb. It sounds exactly like a Mr. Coffee machine making coffee! If you shine a flashlight down the carb you can see it dripping down both primaries. It continues this until it has exhausted the entire fuel bowl! Not a drop left for the primer pump!

I've tried installing spacers under the carb, but to no avail. The carb is nice and cool to the touch when all this is happening. I did notice that the fuel line is really pressurized with vapor though. Also, the fuel filter is never full, it always appears to be about 3/4 full. The fuel filter is mounted vertically. Can a vertical fuel filter be a problem? As I said, this problem is occurring in three carburated cars so I find it hard to believe that the carbs are at fault. Also, the Holly 4412 on the Bronco is doing the same thing and it has less than 500 miles on it. The fuel filters are vertical on all the machines and never appear to be full.

Any help would be appreciated. The constant gas wash on my cylinders can't be doing any of these negines any good...

 

[Tom Mobley]

Tom,

Does this engine have the original intake? These years had an exhaust heat crossover passage in the manifold directly under the carb. There was a stainless steel heat shield shim gasket that went under the carb on this setup. Also, if the heat riser valve on the exhaust manifold is stuck closed a lot of heat will occur here.

Gasoline formulated for use at low altitudes will vaporize very easily with a little heat. Are still working on a tank left over from summer?

Tom

 

[Tom R]

Tom,
It still has the original manifold and I noticed the heat crossover. The stainless steel plate is there too. I left the plate in place and added a VERY thick insulator on top of it. It didn't help. As I said in my first posting, the carb runs cool even after an hours engine run.

I drove it yesterday and clamped the rubber fuel line shut between the carb and the fuel filter. It did not leak down at all. I notice that the fuel filter is never more than partially full and there seems to be a lot of vapor presuue on the rubber line, even though the line is not overly warm to the touch. Any of this make sense?