Does anyone know what the switch or relay is screwed onto the a/c housing under the hood? It has three wires going to it, one yellow, one brown and one black. Mine fell apart. It has a copper coil and what looks like a maybe a breaker on one end inside. It's about 2"x 1 1/4" x 1 1/4".
Also on a different note, any ideas on why my engine falls on it's face at around 4600-4700rpms? It feels like it just runs out of gas till I back off.(71' 350/270 stock, Holly 600 vac. Appreciate the help. Dwain

Replace the fuel filter.

Did that today...no difference

The relay you describe is the heater blower motor resistor. It regulates the hi-low motor speed. Most any of the parts houses or a GM dealer should have it or get it for you.

If you have a stock HEI you may find the ignition module is breaking down under high RPM. They do that sometimes. Not uncommon. Connect a dwell meter to the negative side of the coil and see if it stays consistant at hight RPM. You drive and have some else watch the meter. The dwell will change at high RPM, but it should be consistant, and not bounce around.

A weak ignition coil will do the same thing, as will worn plugs and plugs with too large of a gap.

|UPDATED|1/9/2005 6:32:43 PM (AZT)|/UPDATED|

Thanks Ken. I do have the Petronix Ignitor II and Flame-Thrower II coil, fairly new. Could it be a fuel delivery problem? Like when I'm getting on the freeway, hit high rpms in second or third and shift, sometimes it just stalls for a couple of seconds then catches up and goes on. Maybe carb problem? If so, what could it be? Float level too low? Fuel pressure too low??? What are your ideas? Thanks, Dwain

Even with the new ignition parts, I would do the ignition test.

But yes, it could be fuel related. The best test is to put a pressure gauge on the fuel inlet to the carb and watch the pressure when you are driving. Granted, this takes a fairly long hose. I have taped the gauge to the windsheild many times.

If the pressure goes away after prolonged hard acelleration, then comes back, you have a fuel deliverly problem.

This could be a partly clogged pickup in the tank, a weak pump, collasped flexable fuel line, etc.

If the pressure is good, you can try replacing the filter.

Usually the float won't be a problem if the car ran good in the past, and the carb has not been opened up. When a float fails, or the needle and seat fail, it usually runs too rich or floods. Not your problem.
While the needle and seat can stick shut and cause starving problems, it does not usually act up in the manner you describe.

My car is doing a very similar thing at the moment, but it takes a bit longer to recover. My "s" shaped hose from the frame to the fuel pump has been replaced with standard hose sometime in the past, and the hose collaspes and restrictes the fuel under hard acelleration. I have the new hose, but need to put it on.

You could also hook a propane tank to the the air inlet, and when the car boggs (not until), add a lot of propane. If it runs a bit better, or runs well, it's starving for fuel. If it makes no difference you either don't have enough propane, or it's an ignition problem. The flow from a propane torch is not enough. There are valves that go on the propane tank that can deliver a lot more volume through a vacuum hose.

Starting fluid (either) can be used and sprayed through a hose, but I don't recommend it. The starting fluid burns too fast and can cause severe pinging, and under heavy load could cause engine damage.

Try a few things and let me know what you find. Well go from there.

Thanks for the info. I'll see what I can find...........

One more thing, when you set up the Pertronix, did you set the end play on your distributor? I have the original Pertronix and that was one of the things that was to be done while installing the module. I don't know if it is still critical with the Pertronix II though.

Hmmmm...I don't know, I didn't install it and don't have the directions. How would I check that? Thanks