Posted by Vaughn on Sunday, February 05, 2006 at 12:32PM :
In Reply to: Re: Flathead Valve Noise - Time to adjust Valves? posted by John M on Sunday, February 05, 2006 at 1:31AM :
If the problem appears under a load, then it's not a valve issue, more likely a piston/crank issue or carbon buildup on top of the piston that hit the top of the combuston chamber and can be magnified as temperature in the chamber raises. If you ran a rick mixture for awhile, this is a possibility. You may want to pull a plug and look in the combustion chamber for excessive carbon build up.
To decarbonize the combustion chambers, you can pull the head or rig a way to get water into the fuel and air mixture while at cruzing speed to create the hot burn required to clean the combustion chambers. A good place to connect is at the base of the carb below the butterfly where there is a brass plug. A jug (gallon size) with a rubber line and manual valve that a passenger can administer is a good approach. Only takes about 2 miles to clean. You do however run a risk of carbon logging under a valve and bending it, so you have to consider an option you're comfortable with.
I set the timing on my truck 2 degress BTDC instead of 2 degrees ATDC to get a little better performance and milage. The distributor is not vacuum advanced, and it seems to work well.
Follow Ups: