what gas to use

[19roadrunner70]

i have a 1970 roadrunner with a 440 with an aftermarket camshaft, the fuel gauge is at less then 1/4 and i am wondering what octane i should put in the car.

thanks

 

[bbeep69]

Just to be safe go with the 93 octane for now. then maybe try some 89 next time (1/2 tank or so) so that if it pings you can add the rest in 93 octane.

 

[FatJack]

If you have to use 89 you need to back off the timing a few degrees.

 

[Meep-Meep]

What's your cranking compression? Do you know exactly what cam it has? Most engines with small cams and 8.5:1 CR that blow 150-160 PSI can get by with 87 octane. Starting with high octane and working down until you find the limit isn't a bad idea.

 

[SUPERSTOCKRACER]

I'd use the 93 octane.

 

[zrxkawboy]

Starting with high octane and working down until you find the limit isn't a bad idea.

+1