I am learning quite a bit about heat soak, in which the carburetor soaks up heat from the motor, vaporizing the fuel, turning a strong running motor into a sputtering embarrassment. On my ‘Bird there is a water jacket plate under the carb to help cool it. Turning off a warm engine (to go shopping, for instance) or sitting at idle (at, say, a series of long stoplights) stops or slows the flow of coolant and allows the carb to absorb enough heat to boil the gas.
Not everyone seems to have this issue. Perhaps it is less of a problem for stock setups, and my Edelbrock is just more susceptible. Ethanol blend fuels are said to vaporize at lower temperatures then the gasolines of the past–it’s possible that the blends in my area are higher than average and also contribute to the problem.
I tried a Holley insulating plate a few weeks back. The insulation worked well, but the carburetor made obnoxious noises. I took that plate out and returned to just the stock water jacket.
Last week I was caught doing a series of errands in heavy rush hour traffic. After a few stops and long waits in traffic, the engine started to stumble and idle roughly. With my destination in sight, just across the intersection, I waited three agonizing minutes at a light while the idle got slower and slower. When it turned green, I feathered the throttle and just made it to the parking lot.
Well, that was enough. More research turned up a few Edelbrock insulation products that looked like a better match then the Holley. I found two kinds, wood fiber and phenolic. I couldn’t find anything to say the one type is more effective than the other, so I ordered a half-inch thick wood fiber insulator bored with four holes to match up to the carb correctly. (This thickness leaves about an inch of clearance between the top of my air cleaner and the hood.)
I placed an order with JEGS.com and the new part arrived Friday, just in time to install Saturday morning. Putting it in was simple. (Getting really good at the carb R & R now.)
Saturday afternoon I ran a series of errands in the madness of weekend traffic. We even took in a movie. Hot starts were effortless. No evidence of vapor lock in traffic. It’s hard to say “problem solved” after only a day–but greatly improved certainly.
While I was out in the garage, I sorted though some of the spare parts, trying to free up some space, and came across the washer motor. I think it was removed to make way for a high-performance ignition system (which I removed some time ago). I reinstalled it in what appears to be the original location. If anyone knows how the fluid lines are supposed to run, I would love to hear.
Today, though, I plan to be underneath, changing the oil and lubing the front end.