Oil fuel mix ratio

[Y2K350]

Looking for recommendations. Previous owner was running 30-1 oil fuel mix on 91 pump gas with an octane booster. Pulled plugs and they look to me like it was running way rich as they are black. Engine has been ported,polished and case matched. Old owner thinks that the domes in the cool head are 19cc. Main jet in carbs are 300’s. Exhaust is toomy t5. What are your thoughts?????

 

 

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[hoppedupandcutdown]

Octane booster is junk. And it will jack with the plug color.

I run 20cc domes on 91 at 1200 ft about the same as you.

300 main should not be rich if you are ported, I'm not ported w/T5s and run 280's and I'm a little rich but don't foul plugs.

Most run 32:1 or 40:1. Oil to fuel is not how you determine "rich" Just pick one and stick to it, jet accordingly

I'd check the dome cc's for sure and not run smaller than 20cc on 91

[locogato11283]

I run 32 ounces of Klotz to 5 gallons of fuel. Never had an issue. Race gas 4mm Serval.

[kawa110]

32:1
Caster oil
Weed eater with 87 octane and super tech to “race motors” with vpc12 and maxima


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[Keno]

If old plugs, then who knows. 

Pretty easy to take the head off and check what domes are in there. SHOULD be scribed in the edge of the dome.

[ClaudeMachining]

Check uccr, you dont need to remove head.

Or open the head and check dome size.

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