Fuel Options

[dfrazz]

I have a Mopar crate 360 in a '71 Challenger and am experiencing some rattling at high RPM's and ticking at idle after the engine is warm. I've had a couple of locals advise me to boost the fuel and use a lead substitute. I only had the car 2 months and only put in regular 87 octane. I'm curious what octane you run, if you add octane boost and/or lead substitute. Thanks for the responses.

 

[burntorange70]

Think you should be running 91 at the minimum in that motor. Also make sure you got it timed correctly if you have not all ready.

 

[moparleo]

Your engine has hardened exhaust valve seats so it doesn't need leaded fuel. As far as fuel octane needed, that will depend on the compression ratio, ignition timing, a/f ratio etc... There have been several different horsepower rating 360 crate motors sold over the years. If you bought the engine new it would have come with a spec sheet.

 

[dfrazz]

I checked the timing when I first got the car, it was at 12 degrees at idle at 36 total. Unfortunately, the motor was already in the car so I don't have a spec sheet. Thanks for the info on the 91 octane and not needing lead. Do you add any octane boost?

 

[moparleo]

Octane boosters are not necessary for a street driven car if you keep the timing where it is. If it pings under load, you will need to back the timing off a degree or 2.

 

[burntorange70]

The only thing octane boost does is lighten up your wallet.

 

[ramenth]

Yes, yes, and yes, to Leo and Russell.

Are you running a vacuum advance?