I didn't break anything which is good :TU: but only one issue excluding the brutal heat. made 5 runs between 6:37pm and 7:51pm. On all 5 at approx 5300rpm in 3rd gear, it was like I hit a rev limiter. Then the car was back to normal. it was a split second, but just enough that my speeds and ets were off. But considering the heat I can't complain too much. When the sun started to set and it got a little cooler, the hesitation (didn't seem like a bog of the carb though) was a little less pronounced. If I remember correctly, I think some people have said the Carter mechanical fuel pump has been known to not provide enough pressure at high rpm. Yes, I'm running a Carter. I also only had 1/8 tank of gas and it was sloshing. Or maybe it was the heat. o No: Or maybe it was a combination of all 3 o No: Any ideas? My 60 fts got better though then a couple weeks ago. I tried brake torquing at the line to approx 1300rpm and my 60s were 2.30, 2.26, 2.27 then identical 2.240 and 2.240. :TU: One run I was squared off against an 05 Mustang GT. I got him at the line and we were neck and neck the entire track with him every so slightly nudging ahead. Then the hesitation on my car and I was done. his 14.26 @100 to my 14.53@91.99
Chris, I got your call. Having phone problems again I think your right on the money with the problem you had. More fuel in the tank is an easy baseline and cheaper than a new fuel pump and full tank Good job on lowering the 60 ft. Lower et's are around the corner. Matt
Most of the Pure Stock people run full or almost full tanks when they race. I had the exact same problem you describe here on my car at Martin. Threw in 5 more gallons and it cleared right up. Thanks to Rusty for that one. Easy to forget some things. Gauge showed 1/4 tank, but what does it know? :laugh: :laugh:
Thanks. I had no problems with 1/4 tank from a couple weeks ago. guess I need to keep at least that much in there. I was comparing my timeslips from my last 2 runs 14.48 and 14.47 to my 14.31 run from a couple weeks ago and they are very close. the 2 yesterday were a tick better at the start, but you can see that advantage start to go away at 330, 1/8, then 1000. So it looks like with a low fuel level in the tank, the higher rpms are causing fuel starvation. Sooooo, put more fuel in the tank. simple fix, we like that :laugh:
Dave and you other pure stock guys....how about the tip on how you restrict the return line on the stock pumps.
What's the theory on restricting the return line -- the returning fuel aerates what's in the tank too much? Chris, if it was a flat-on-your-face stumble, not just a couple cylinders mis-firing, then I agree it's probably fuel delivery. In my experience, when you have such a problem, the symptom will be remarkably consistent (this many RPM in this gear), like you observed. I think anything over a quarter tank should be fine. It seems hard to believe that at the top of 3rd gear all the fuel is still sloshed to the back of the tank. Let's face it, our cars don't pull that many g's. Keep in mind it's easy to fool yourself into thinking you've fixed a fuel problem. There may be one major cause, and several other minor contributing factors. If you addres one of the minor factors (add fuel to the tank, replace the fuel pump, etc) the problem may seem to go away, but you are probably still on the hairy edge of it happening again (which also means you'll be running leaner than desired). Example: My W-30 had a fuel problem come and go for a while. It wasn't until I dropped the tank that I found the root cause. The sock on the pickup was folded across the opening such that all the fuel was being sucked through an area on the sock the size of a dime -- which means all the dirt in the tank was also trapped on that small area. Whoever installed the send unit was careless and didn't get the sock straight.
