race gas revisited, why and when? Options

[Trekkor]

Bought a five gallon jug of leaded 110 octane "VP" brand racing fuel. (IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif)

My motor seems to have higher than stock compression. Lowest is 160 PSI.

My speed shop guy says the valves will like the lead. (IMG:http://www.914world.com/bbs2/html/emoticons/chowtime.gif)

Maybe I just like throwing money out my open windows at speed... (IMG:http://www.914world.com/bbs2/html/emoticons/huh.gif)

KT

[ArtechnikA]

QUOTE (trekkor @ Apr 9 2005, 08:17 PM)

The acceleration is smooth then the power COMES ON after about 4500rpm's in a BIG STRONG way. (IMG:http://www.914world.com/bbs2/html/emoticons/clap.gif) Drove it out to the track today. I only noticed a little popping and sneezing out the carbs on cruising speed. Say 3000rpm's KT

cool. that's where your cams come in.
but it has nothing to do with your ignition advance curve...

this is not a seat-of-pants thing.

the best way to find out what you've got (besides probably 5* too much advance) is to pull the dizzy and have it checked out by someone with a distributor machine. the correct curves are published in the factory workshop manuals; if you have the distributor number (ideally, the Porsche number although the Bosch number isd better than nothing...) we can track down what the curve *should* be.

lacking that, the best thing to do it watch the timing marks with a timing light, which i understand is a PITA on a /6 (BTDT). the next time i install an engine in a /6 i'm going to put different-colored paint dots every 5 degrees from Z1 to 35* si can see right away what it is i'm looking at... anyway - you need to verify that the advance comes in -relatively- smoothly. there are a couple of little bumps but basically it's pretty smooth. what it should *not* do is come in very quickly at too low rpm (like the dizzy in my E does - it's basically all in by 2500 and i have to be pretty careful with lugging. i'll fix it when the engine comes out...)

the popping and sneezing sounds you have a bit of the standard transition-to-mains Weber flat spot. i would try to go up a couple of steps richer on the emulsion tubes.