Besides trying to get past emissions here in Chicagoland, I have been playing with WOT timing and fuel trims. My primary objective at this point has been to eliminate detonation at WOT. I have done this following the procedure of slowly eliminating knock retard degrees while dropping WOT timing and richening up WOT fuel. Now I have gotten to the point where I am getting 0 spark counts at WOT and having 0 knock retard degrees. My question is, now that I get no spark counts at WOT, how many degrees of knock retard should I plug into a final bin as "insurance" against things like bad fuel or some other unforeseen problem. The heads I am using are the TFS23d with 64cc chambers. I've settled on 34d total coming in at 3600rpms.

 

In one step atta time, try dropping 2 degrees at time, until you feel or can find a lose of performance. You want to have the min amount of advance that allows the max amount of perforance. As opposed to the most amount of advance without detonation. There should be a few degrees difference between the two, and that's enough to allow a tank of fuel being a little stale of a bad hair day, without having to hit the K/S.

 

Bruce,

Good to hear from you again. Hope you had an enjoyable trip to the Southwest. If I understand correctly, you're suggesting that the "insurance" should really be built into the main spark curve rather than using the knock retard tables as the "backstop". :hail: Anyone have experience with these heads?

 

Trip got cancelled.

You can use the K/S for insurance it's just that it takes out more then enough timing to stop the detonation. So it might pull 3-4d when 2d different in the table would have stopped it. Long term it's easier on the engine to be back a few degrees from borderline detonation. BUt, again, you have to have the fuel right.

34 for 64s sounds close. But, everything seems a touch high to me.

 

Bruce,

You're right about the fuel. Right now I have it set at 11.9:1 for anything above 3200rpm. But I don't know that's right yet. Not sure it even gets there since I don't have WB on it yet. Still wrestling with getting past emissions. Hoping to do another pass today and see where I stand. Feel pretty good about the cal I have plugged at the moment. Found out I had a small vacuum leak at the PCV. Crack in the plastic connector to the manifold hose.

 

You knew about the WB years ago.....
Hmm, didn't we even have it on your car?.
Dunno how much of a difference it would have made with the sniffer thou.