Autolite 86 spark plugs=good for 68 383?

[Billccm]

Hello:
I've had my Road Runner since January. It runs great, but at idle a little rich. It is a 383 auto, 650 Edlebrock, Edlebrock performer intake, MSD Street fire ignition, MSD distributor, and MSD wires.
I adjusted the carb idle with a vacuum guage. It was 9 inches when I started, and tweaking got me to 11.5 inches.
I have not checked the timing, yet.
I decided to (finally) get around to pulling a plug off each bank. The plugs are Autolite, marked '86'. They look good (electrode is square), but slightly sooted. Still running rich, so I will look into carb jets a little later.
Question for today: Is Autolite 86 a good plug for my application. I searched the forums before I posted and I see NGK and Autolite mentioned, but wanted to get an experts opinion. I'll check the gap on the two plugs and if they look good I'll work on carb jetting next.
FYI: The seller had a cabin in the White Mountains (Arizona), and mentioned to me that this was his car that he drove up to the cabin (big car show there twice a year), and needed it a 'little rich' for the mountain driving.
Thanks for all of the replies. Take care, Bill

 

[lewtot184]

86's are a little warm. about like a j13y or j14y. I'd do some jetting/float level checking. fuel pressure may be an issue too.

 

[Frank Mopar]

First thing after the plugs is to get the correct springs on the metering rods in the carb. It goes by vacuum and you will be a happy camper

 

[Billccm]

Thanks for the replies. I pulled four plugs and they were all a little sooted. Gap was precisely 035, so I need to look at the carb next.

I'm returning to summit racing my second time spark plug wires. Can't get a set that fits. Going to try firecore next.

 

[Billccm]

Lots of contradicting info on spark plug gap. I've read keep 035 per the factory specs, and take it to 050 if you have MSD. I dug out the Street Fire ignition manual, and it says spark plug gap is really important, etc, etc, then mentions to open the gap in 005 steps and check performance. Yea, right I'm sure we all take the spark plugs out 20 times and tweak the gap in 005 increments. I can't believe they actually wrote that in the manual.

A few threads on the A body forums say 040; what is your take on this gap?

To reiterate, 68 383, Edlebrock Performance intake, Edlebrock 650 carb, MSD distributor and Street Fire ignition and coil.

Thanks again!

 

[lewtot184]

I've never found any performance gain by increasing plug gap. i'd use .035" as a minimum and .040" as maximum.

 

[Billccm]

I've never found any performance gain by increasing plug gap. i'd use .035" as a minimum and .040" as maximum.

Are you running MSD, or Orange Box ignition?