When your street car is faster than their all out racecar that's a nice feeling. Oh that's classic !!! :laugh: I absolutely love that !!! :laugh: John Biggs.
Just to let you know, way back when (15 years ago) I tried my Dodges 26" X 9" tires compared to my 32 X 14s I used to use and got absolutely no difference (.02) between them at our SHORT TRACK. I think he should try some shorter tires anyways, with those times and the new compounds these days it should hook better no matter what. Mickey Thompson has down to a 20.5" diameter slick, if you could borrow some to try first it would be best. And you should keep the sway bar if you want it to handle on the street, it won't make a big difference at the track unless you tune the rest of the suspension too. Looking forward to see what happens, with all these ideas everyone has you'll be busy. <!-- / message --><!-- sig -->
I see your running your timing at 35*. read the timing post on the board, it may help to back it down a bit.
Well heres an update. Maybe I found part of the problem. I took Jims advice to heart and started looking for a fuel supply issue. I was running a holley HP125 electric fuel pump with no return. I had a mallory regulator and the parts to convert it to a return type fuel system. I plumbed the return line and dropped the fram canister type filter for ahigher flow inline filter. I also planned to update the carb inlet lines to -8 hose instead of the chrome 3/8' lines. I was a little surprised to see how restrictive the float bowl inlet were compared to the -8 inlets I am upgrading too. Attached are some photos of the old and new inlets.
I am also installing jet extensions. It looks like this is something I should have done some time ago.
I was able to get the car back out to the track this weekend. My first couple runs had to be aborted due to low fuel pressure. I had adjusted my new fuel pressure regulator to 5.5 psi at idle but the pressure dropped significantly during the run down to about 3 psi or so. I adjusted the pressure regulator all the way up as high as it would go (about 6psi at idle) and it still dropped to 4.5 psi during the run down the track. I was able to get a few full passes although the tires still wouldn't stick coming off the line. My best pass was a 12.09 at 113 with a miserable tire spinning 60ft time of 1.80. My AF ratio down the track hovered around 12.3:1 . I noticed a miss while running and after driving home I found that number 8 plug was fowled. I tested compression in #8 and #7 (which had a clean plug) #7 tested 190 psi while #8 only managed 165psi. I squirted a little oil in #8 and retested and it popped up to 190psi so I think the rings must have been washed down from the fowled plug, so I may have been running 12.0's with one fowled plugo No:
Your mph is reflective of a high 11 sec. run. Once you solve your traction issues you'll be there for sure. John B. :TU:
I agree. My car runs high 11.80's at only 111 mph. Now I still have just a stock fuel system with a stage 1 pump. And I do believe that it starts to lay down on the top end. I'm actually going to try and shut off the return line to the fuel tank this year and see if that helps.
I pulled my MT ET street slicks off yesterday and they appear to be about completely worn out. I assume that the fake tread cut in the tire serves as a wear indicatoro No: Maybe thats were my traction is going. I'm probably going to have to buy some new tires now. I guess I might go with the MT drag radials. So the question is, should I go with a shorter tire or the same size tire and deeper gears if nessesary?
With 3.50 gears and 28" tires, 114 MPH is 4788 RPM with no converter slip. With 26" tires, that becomes 5156 RPM. I say go with the P275/50R-15 MT ET Street Drag Radials.
I am just finishing up my 3 week work rotation in the arctic and will be back home in a couple days. When I return I will be heading back out to the track to see if I can get my car to perform like it . After consulting with a few experienced people (thanks Jim Weise and Chris Skaling) I suspect that I have a fuel supply problem caused by a weak fuel pump and or insufficient tank venting. I also had traction problems that I can attribute to my slicks being at or beyond maximum wear. I have procured a Mallory 140 gpm pump and a better pair of slicks. Thanks to Joe Iacovoni and Tom Hearsey.
I can't wait to see how you make out:3gears: Did you find out if Rick or Dave has the slicks? If not I will make some calls to track them down, let me know if I can do anything eles to help out:TU: Thank you to Rick Henderson for picking the slicks up, they are going to a good cause........Chris
Well I installed the Mallory 140 pump and adjusted the regulator to 6.5 lbs, now the pressure only drops maybe .5 lb under hard acceleration. Thats got to be a bit of an improvement from the 4 lbs it was dropping too. Friday its off to the track to see what happens.:3gears:
Friday won't come soon enough:laugh: Did you get the slicks? With it running, can you turn it up to say 7.5 psi? I can't remember if I asked you, I'm sure I did but how is the pump wired, hot and ground side. Did you check the voltage at the pump? I can't get past why you couldn't turn the pressure up. Check this out, cable drive fuel pump......... http://www.chevelles.com/forums/showthread.php?t=213898&page=5
Yeah Chris, I can turn the pressure up higher no problem. Should I be looking for 7.5? I had to turn the regulator way down to get 6.5. I believe there was something wrong with the holley pump. I'm driving up to Ricks in the morning to pick up the tires.
Sounds like the old pump was screwed up, is this the same pump you were using in the past with your engine grief? Just for now if it will idle nice, 7-7.5psi until you get to the track and see how much it drops. Maybe stick a half a tank of fuel in it also. How did the tank vents look?Chris
