I have an 82 Mercury Cougar station wagon with the 200 six and the proper Motorcraft (holley 1946) carb.
The car runs great at idle and all speeds. Passed the California emissions test last March after months of problems with carbs and also had the head inspected, cleaned, valve seats ground and one new valve installed.
Here's the problem: After running at full operating temperature and parked for 20 minutes or so it's flooded but not severely but enough to have to crank for 10 seconds or so and when it starts a nice amount of black smoke from the exhaust. I cannot catch any boilover from the bowl. No dribbling....nothing. After a couple of hours there's no problem starting. The car has sat for up to two weeks and it starts instantly after setting the choke.
I have set the float 1/8" lower than spec (spec is even with the top of the bowl) because of the boilover problem here in the summer. Our daytime temps run up to 115* and usually average above 100* June through August. The problem occurs even now that the outside air temps are in the 30's overnight and highs in the 70's daytime. The car is factory stock. It does not have a water cooled base plate nor does it have any sort of heat shield nor did it come with those things.
If the bottom plugs were leaking I would expect the bowl to empty over a couple of weeks.
The accelerator pump wouldn't siphon, I think, especially since it works great. And I think I'd see that dribble from the port in the throat.
How about the power valve? Could that siphon fuel out below the throttle plate? I think the only port below the plate is the idle port, and it's such a simple vacuum operated device I'm wondering if it could be a problem at all.
So, how can fuel dribble in to the intake without me seeing it? I know fuels have changed over the years and result in wierd problems and I would expect that the car did not do these things when new even here in the desert.
Thanks in advance for any ideas.
The car runs great at idle and all speeds. Passed the California emissions test last March after months of problems with carbs and also had the head inspected, cleaned, valve seats ground and one new valve installed.
Here's the problem: After running at full operating temperature and parked for 20 minutes or so it's flooded but not severely but enough to have to crank for 10 seconds or so and when it starts a nice amount of black smoke from the exhaust. I cannot catch any boilover from the bowl. No dribbling....nothing. After a couple of hours there's no problem starting. The car has sat for up to two weeks and it starts instantly after setting the choke.
I have set the float 1/8" lower than spec (spec is even with the top of the bowl) because of the boilover problem here in the summer. Our daytime temps run up to 115* and usually average above 100* June through August. The problem occurs even now that the outside air temps are in the 30's overnight and highs in the 70's daytime. The car is factory stock. It does not have a water cooled base plate nor does it have any sort of heat shield nor did it come with those things.
If the bottom plugs were leaking I would expect the bowl to empty over a couple of weeks.
The accelerator pump wouldn't siphon, I think, especially since it works great. And I think I'd see that dribble from the port in the throat.
How about the power valve? Could that siphon fuel out below the throttle plate? I think the only port below the plate is the idle port, and it's such a simple vacuum operated device I'm wondering if it could be a problem at all.
So, how can fuel dribble in to the intake without me seeing it? I know fuels have changed over the years and result in wierd problems and I would expect that the car did not do these things when new even here in the desert.
Thanks in advance for any ideas.