More fuel issues, i guess?

[rickf]

The timing advance is a good suggestion, If the springs are broken or deformed the pattern of problems would be consistent but if the mechanism is rusty and hanging up it will give the symptoms you have. The fact that you have points it is simple to pop that points plate out and look at the springs and timing assembly. And I also second what George said, with points you could have a bad condenser at the points or another place to look is the inlet capacitor where the power wire enters the distributor. Those seem to be going bad a lot lately, probably due to the age of them. If you are a bit creative you can disassemble the capacitor and solder a wire to the pin and just eliminate the capacitor and run the wire up to the coil. This capacitor was there originally for radio interference suppression. It has no effect on how it runs, unless it fails.

[muttguru]

AG Wrangler......

I'd like to know what version of carb you have....you still haven't told us what it is

ken

[agwrangler]

I havent had a chance to run out and get photo of carb or model number. am on work travel, will be home tomorrow!

[buttanic]

For what it's worth AV gas has a lower vapor pressure than automotive gas so it is more susceptible to vapor lock. The lower vapor pressure lets it vaporize more easily at cooler temperatures at altitude in aircraft. It might not be a good choice in hot Texas weather.

The formulation for aviation gasoline
continues to be relatively unchanged for
the past 50 years.
It must satisfy these basic requirements: 1) Vaporization must occur
easily at low temperatures but yet not so
easy that it will cause vapor lock; 2) It
must have a high energy content per
unit weight (BTU), and permit high
compression engine operation without
detonation; 3) It must be relatively free
of gum-forming compounds; 4) It must
have a low sulfur content to reduce
corrosive action; 5) It must be stored
and delivered free of contaminants.
Volatility considerations are important because of the effect on
carburetor icing and “vapor lock.” Vaporization of fuel in the carburetor
venturi cannot take place without heat
being extracted (latent heat of
vaporization). If too much heat is taken
out during the vaporization process
there is danger of carburetor ice forming
with float-type carburetors.
Highly volatile fuel extracts more
heat from its surroundings than does a
less volatile fuel and tends to allow
vapor (bubbles) to form in the fuel
lines.
Bubbles in the fuel delivery system,
prior to reaching the point of
atomization in the carburetor, cause an
interruption or reduction in fuel flow
(vapor lock) and complete or partial
engine failure due to improper fuel-air
mixture. Reid vapor pressure is a
measure of fuel volatility and is closely
monitored and controlled within an
acceptable range for use in aircraft.

[rickf]

What is the Reid vapor pressure rating of Avgas compared to automotive motor fuel? I understand the principals but I do have to say I never had any trouble with Avgas when I was able to get it ( it is illegal to run in a motor vehicle in NJ since it is not taxed as a road fuel) and I haven't heard of anyone having vapor lock issues with it without underlying causes. I am hoping Raymond chimes in on this since it is his area of expertise.

[rickf]

While researching the Reid vapor pressures I came across this thread. Some interesting reading here.

http://www.clubdbsa.org/forums/showthre ... e-hard-way!

[buttanic]

Digging further.

http://www.vansairforce.com/community/a ... 32994.html

[agwrangler]

Ok, so it isn't the carburetor. I fiddled this weekend, and it has to be a distributor issue. If i loosened the nut and adjusted the timing, i could get it to run a little better, but then when i tightened that bolt back down, it would run AWFUL. No matter what I tried, i could get it running great, then tighten that thing down, and it would run bad. I am going to replace the whole distributor with a NOS one and see what that does when I get a chance. Such a pain the the rear.

[rickf]

Have you checked the springs and weights on the advance in the distributor?