Lead additive

I recently decided to throw some lead additive in my tank thinking it would be beneficial since i dont have hardened seat in my iron heads. Well i ended up with a run on condition when i shut it off that i never had without the additive. I used motor medic lead substitute. Why did i get this condition? Engine is 11.5 iron headed solid roller, forged pistons. Makes about 575 flywheel. I run it on 94 all the time and it runs great. Occassionally ill run 50/50 94 and sunoco 110 race gas from the pump.
Thanks
Bob

Sounds to me like you now have deposits in the chambers that are causing the "glow plug" effect. Aside from that, I think running 94 octane in an 11.5 to 1 iron head probably makes for a pretty hot chamber to begin with.

I'd pull the heads, clean 'em up and do the seats. Otherwise, I'd resign myself to running better fuel...and stick with ONE fuel to keep the tune where it belongs. Changing fuels and/or blends can make a big difference in AFR and timing requirements.

Thanks Maverick . So it would be best to run the 110 all the time? It runs great with the Sunoco 94 so im gonna stick with that unless i run the 110. I was just reading that there really is no need to run the lead additives. Most of them seem to contain petroleum distilates which are bad . I may take your advice and pull the heads this fall.
Bob

If you're happy with the way it runs on 94, then stick with it...apparently the tune is pretty good for that fuel. Definitely freshen the heads with new seats, tho.