Need help from some pros

[Rob Petrie E395]

Originally Posted by Footbrake

Although I'm just a bracket racer I thought maybe some of you professionals could help me out. All of a sudden my car has slowed down. 2 weeks ago I was going consistent 8.18's,8.19's in the eighth mile. Last week car started going 8.40's, 8.39's with almost 3 mph loss also. So I thought , maybe the track, air, etc. you know the deal. Last night car went the same 8.45,8.42,8.39, still down on mph also.
First round I dialed 8.38 figureing I could just run it out and still be good with no worry. Well I broke out with a 8.372. Is this car telling me that it's too rich and wants to run faster as the night gets cooler?
If I advance the timing 2 degrees will this lean it out a little and tell me if that's the case, or do you think something else is going on here? It's a 454 motor with the timing set at 35 degrees right now.
Any help is greatly appreciated. I'm beside myself with this problem. Thanks-Russ

You stated that you thought it might be the weather and it very well could be. what was the DA for each run, if you are 2/10 off in the same air conditions you most likely have something going on. But if the 8.18 is at lets say 1000da and the 8.39 is at 3000da you could be ok the engine is just giving up .01 for every 100 feet or so in density altitude. just my .02 but more info would be needed to say if the weather or something else is to blame.