Zephyr's got the percolation blues (HELP!) (link)

[Tom Wells]

Tim,

The spacer is Edelbrock's 0.3" thick one. I already had to reduce the height of the air filter from 3" to 2-1/2" to accommodate it.

Gene,

The pressure gauge is at the carb.

The pump is in the rear, just next to the gas tank. The reg is on the firewall, well away from the exhaust (as in about a foot).

All,

One of the guys here thinks the underhood temp is the problem, as it isn't well ventilated. The carb works fine for an hour at a time on the highway; no problems. When I stop and the heat builds under the hood, the Vesuvius starts. And keeps going. The bottom of the air filter becomes way too hot to touch. And the engine compartment is pretty full!

So I'm going to do an experiment -> run without a hood for a bit, as a test.

If all works OK then I need to start to make the fake scoop into a real one, maybe open up the fake fender louvers and louver or otherwise vent the rear part of the hood.

I'll report back after the experiment.

If that doesn't work, maybe the return line could be the next experiment...

Tom

[mreid]

Tom, that thing is awesome! Completely agree on the underhood temp as the primary problem and it sounds like your experiment will confirm it. Even with the air flow enhancements, you may still have the problem on hot days when idling. If you are using a dropbase air cleaner, it will trap manifold heat and boil the carb. Is there any way to get a thicker spacer under the carb once you open up the fake hood scoop? While I still believe the return regulator would help some, I don't think it is a primary solution. Lowering the underhood temp is though.

By the way, I thought you might like a couple shots of my 1970 Mustang. I put a 460 init and had at least two of the same issues - exhaust (had to fab my own headers and exhaust) and fuel percolation (different air cleaner, cowl induction hood, and return regulator). The cowl induction hood gave me both better air flow in the engine compartment and more room to raise the carb and air cleaner. Just a thought. No problems after those changes:





Mark