Oscillating idle when hot

[Unique427]

Originally Posted by fastd

SBSerpent,
Did you search for Sunoco race fuels gas stations specifically? Also, you may be able to find some race shop locally that sells higher octane fuel.

I had the same issue: phenolic spacer helped a bit; when I added fuel injection it fixed it; I’m sure the return line helped. You could add a return line and spacer, find some place to add 5 gallons (or more) of race fuel to a tank.

Can also buy online and have it shipped to your house in 5 gallon steel pails.

Sunoco 260GTX unleaded non-oxy has a Reid Vapor Pressure rating
of 4.7 and only a 10% evaporation rate at 182F.

As others have stated, a fuel return line can help in some cases. Where
it's less helpful is when cars have a low hanging metal fuel tank with no
non-metal barrier between it and asphalt. The radiant heat coming
off the road on a hot day can heat fuel in the tank to +100F with enough
road time.


Sunoco's write up on Reid Vapor Pressure if interested:
https://www.sunocoracefuels.com/tech...pressure-vapor

Sunoco 260GTX
https://www.sunocoracefuels.com/fuel/260-gtx