Hello Everyone,

I have a ZZ502 in a ’69 Camaro that has run more or less trouble free for the past three years. This season has started with a problem that I just cannot seem to isolate.

At water temperatures between 180 and 200 degrees, the engine seems to flood out and stall. It is very repeatable. I get a strong fuel smell out the tail pipes, but no black smoke. Sometimes I can feather the engine through it, other times the engine just dies. I have to wait until the engine cools down below 180 degrees before it will start and run smoothly again.

I have tried two different carbs (a BG 850 Vac Secondary, and a BG 850 Vac Secondary with annular discharge boosters). I have also tried two different coils, two different coil wires, and two different distributors (MSD). I have checked the fuel filter and float bowls for debris, and they were clean. The gas tank itself is brand new (3 years old). When I changed carbs, I changed spark plugs.

The one common thing between the two systems are the plug wires (MSD), but these are only a year old.

I cannot seam to find what is breaking down with temperature, or what would cause the flooding condition. Everything I can measure so far remains constant between running smooth and the stumbling/flooding condition.

When the engine starts to stumble, vacuum remains solid (idle vac. is 12”), timing remains steady, voltage to the coil remains steady (12 – 13.5 volts), and fuel pressure remains steady (6 lbs.).

Any ideas? Has anyone had this problem before? I am running out of things to try.

Thanks and Regards!

sounds like vapor lock. I would try a heat shield between the carb and intake. It may be boiling the gas in the float bowls causing this. just a thought

Thanks smittyocat,

I've considered the vapor lock angle, but I can see in the sight bowls that the fuel is still liquid, and I can put my hand on the bowls, so the temp should be no where neer boiling point.

Is there any reason why the fuel would boil at a lower temp? I really don't consider 180 to 200 degrees hot. Plus, this has been the normal operating range for the past three years without any such problem.

check this link it explains vaporlock somewhat

http://www.madsci.org/posts/archives/aug99/934767548.Ch.r.html

smittyocat,

Thanks for the info. I quess there is more to vapor lock then I thought.

Since I haven't needed an insolator or other thermal barriers befor, I'm going to try a fresh tank of fuel first. If it acts the same, I'll go with a spacer and insulate the fuel line.

Again, thanks for the link.

Kind Regards!

Glad to help out ,let me know how you make out with the problem.