Well finally heading to LVD track 1st time this year.Caltracs,aluminum rims,softer clutch,RANCHO ADJUSTABLES and new 27 QTP dot slicks with no tubes are new this year. Looking for starting air pressure on the 7" rims. Old tires were 26 8.5 et drags and ran around 19 lbs on 7" ralleys. Car is 3280 lb 66 5 speed nova and hoping to better last year 12.46 111mph 1.77 60foot best. Any opinions on air pressure are appreciated. thanks much, AL

If you were hooking at 19psi on a shorter tire you should be able to add an additional lb with the larger contact patch and very soft QT Pros.

The mph posted suggest some loss of traction, and with the addition of the Caltracs I wouldn't be surprised if you could get into the 1.6s, 60 foot times. Minimum psi for a car your weight falls at around 16psi and that's what I'd use as a conservative starting point. Work up from there a lb at a time until a drop in 60' times, then start tuning the Caltracs.

After your first run, your tires will pick up 1-1.5 psi. This is why some people mistake a big burnout for added mph when they have simply raised the psi via heat. More air pressure equates to less rolling resistance and the goal should be to raise psi until 60s go away or uneven tread wear.

Again, I wouldn't start adjusting the Caltracs until I see the first drop in 60' times with incrementally added pressure. Making multiple changes after a run just leads to a tremendous amount of frustration.

Best of luck, keep us posted.

I don't think a 1.77 in a mid 12 second is too bad. A 1.65 second 60' is generally more like the 60' of a 11 second @ 115 MPH car. I doubt it is going to go more than low 12's at 111 MPH.

My bro in laws 69 Chevelle runs 11.90's at 111 with a 1.64 60 foot. So I guess it can be done!

Unless the loss of traction is causing an erroneous jump in mph, there are likely a couple tenths to cut off the ET. A previous post suggested the same car went the same ET with a 1.9x 60' time. The taller tires should help a steep starting line final ration and help mph at the top end.

Well had a surprising day with goal met and a best of 11.97 at 113.86 mph and 60 footers between 1.67 and 1.70. Launches were 4000 with small bog at 1.67 60 foot, to 5000 launch and spinning 1.70 60 footer.Started at 16 lbs and went to 15 lbs with still good stability through traps.Other 2 runs were 12.01 and 12.02 so pretty pleased with new caltracs consistensy and getting into 11"s 1st day out with new clutch,ranchos and caltracs.Rickster tells me 11.7 is in the future with tuning,launching and cooler weather which i think is great for this 9.8:1 327. THANKS AL

Congrats!

That's definitely a good day out. I'd try to keep your inflation rate at 16+ as any lower and you're likely to get some distortion of the contact patch. As soon as you start developing any tire wadding from lower pressure you create an inability to get proper heat into the tread surface. Add in the extra rolling resistance of lower pressure, and you're likely losing some speed down track.