Would like some thoughts used a 5000 CTC converter would stall right at 5000 5100 from what I seen yesterday.

Overall I was happy with my car yesterday best run was a 10.56 @ 125.95 in to a real strong cross wind but elevator shaft air. 70 deg, low humidity and 29.3 barometer (sea level setting) (102.6 Canadian local correction 30.2 inches local correction by local weather) track is at 620 feet and my cheap weather station said 575 feet (not a corrected factor like a tag or others give) Like a cool crisp fall day. no track spray to speak of and lots of street cars so I would hook go 4 feet spin then seem fine the rest of the way down.

But seem to drive through the converter in drive for 13% converter slip (if that is what I was feeling shift was firm but RPMs did not drop like normal)

Too much stall for my 3600 lb car and motor??

Funny Ran 10.60 @ 125.17 7400rpm out the end put the timing back 5 deg from 42 and rpm out the end dropped 400 and mph only dropped .6 10.68 @ 124.42 7000rpm then put timing back up to 40 and out the end rpm went up 450 with 1.5 mph gain 10.56 @ 125.96 7450 slip seemed to be 13% then 8% then 13% over those three runs??? all short times were 1.49 (felt if I had no spin they would have been 1.43 to 1.44?? but you take what the track gives! LOL!!!)
Guess go back to last years 4000???

Thanks for any thoughts

Oh
1968 GTX Weighs just north of 3600 with me in it
452 cubic inches
Dana 4.56
11.5 to 1 (94 pump gas)
Normal shift RPM 7500 to 7600
Hand ported Indy SR welded runners opened to max wedge so turned into 440-1 2.25 intake 1.81 ex.
roller 272/282 @ .050 duration .694/.715 lift with 1.6 rockers (cam 110 LSA and in at 100)
Phoenix 29.5 X 11.5 (30.2)

Just wondering would a little more line pressure help a bit with the converter sip if it is that close to the edge where it is 13% normal 8% then back to 13%???
need some help hear guys!

Unless you have digital read outs of driveshaft and engine speeds, the % of slip is easily miscalculated. Also, some converters just work well with a good amount of slip. Mine I am sure is very high, but yet the car does well. My trap rpm went up over 400 rpm after I had the converter loosened but the ET got better by .o5 or so.
I trapped 7800 rpm, 33 inch no growth radial slick, 4.56 gears. Comes out to 10 percent.

Ok thanks guys I raised the line pressure two turns and am going to make some TT's tomorrow and see how it all works. then I'll have to decide to live with it or pull it check everything and put my 4000 back in.
Works fine on the jack stands!!

When you say you're seeing the slippage vary from 13% to 8%, etc., is that showing up as differences in the MPH or only the indicated RPM?

Mine is extremely consistent in RPM vs MPH from pass to pass. I can tell how the atmospheric conditions affect the car's MPH on it's first pass of the day by where the RPM is going through the traps.

well normally mine is like that too but when it felt off to me was when the RPM was up and when it felt solid it was down may have fried the clutches when linkage was off and it had major slip in drive on second run. some debris so I'll make a couple hits tomorrow and then pull it out if it's off it clutches are burnt it is likely from when linkage was off. still not happy with shifter think I'll buy a new one this is 10 years old and at least needs a cable???
Thanks again!

Pulled the pan Friday and it seems when the shifter linkage was off and it slip baddly in drive it burnt some clutches, was some debris in it. I up the line pressure a tad and went to a TT day yesterday.
Hotter first run was 83 deg and last was 85 baromiter fell to 29.1 (sea level setting) humidity was not to bad and we had a head wind.
By my little weather gauge altitude was 724 to start and 762 last run this in not corrected track is about 600 feet

1st run 10.59 @ 126.2 felt great 7000 out
2nd run 10.56 @ 125.75 felt a little slip 7150
3rd run 10.64 @ 123.8 slippping 7400
all 60's 1.44 to 1.46
4th turned timing back run was terrible 60 spun bad and slipped in drive for a 10.89 @ 122. 7400 out the end
5th let tranny cool and went in the gambler 1.44 short 6900 out the end for a 10.69 @ 123 into a stiff head wind (red light LOL)
6th let it cool good again put timing back up and 10.57 @ 125.6 1.44 60 foot 7000 out the end.

Seems if I when I go up and the tranny is less than 120 it don't slip if it is over 140 it slips this was more of a test on ther converter knowing I had done some damage to the clutches Thursday!
Have to pull it today and replace the clutches and steels
Shifted at 7600 into drive drops to 6500 solid shift and seems to hold there as car catches up then pulls up nice from there when it's cool?? any more thoughts.

Converter seem fine is the highest stall I have ever had.

I don't think there is anything wrong with the stall number, but the variation in finish line rpm/slip is distrubing. Hopefully that is your trans high gear clutch and you take care of that.

I have also seen a 727 do weird things with the fluid only a little bit (1/2 qt) too low. I think that is aeration of the fluid when the valve body gets exposed and the seals spray instead of being submerged in fluid.

Thanks going to down a pot off coffee and get it out.
replace the clutches and steels and back in to race on Friday.
New shifter cable too!!! Weird if you hook it up the normal way with shifter in park and tranny in park it won't start and of course drove in N and slipped bad in drive.
put shifter in 3rd and tranny in third it works but I guess I had already burnt it up. 10 years with this shifter and it's the first time I had to set it up that way but cable is 5 or 6 years old.

It ends up it is the band that is hanging up. Its warped and I should have seen that seen it was hanging up last time but thought I had it too tight even though I could clearly see it was hot on one side but I cleaned it up and put it on anyways. Think it got warped last fall when the sprag was hanging up (case wear)
i had one warp before and did the same thing???
I have a performance flex band hear I may use clutches look good no marks on steels??
I will have to check everything before putting it back together
Going to change out the servo too to a billet if I can get one quick!!

Glad you found the problem
Not a whole lot of input for you on this one

Need a sounding board as much as some advice with the band warped like that it does not adjust up right. you can be too tight on one side, or too loose on the other and it slips applying second which is what happened this time.
since I have had two of the solid bands do this in the past 7 years think I'll just go performance flex!!!
Thanks again.

Part of the problem if not all was the shift leaver on the transmission the cable goes into. it was worn and even fairly tight could work one way or the other.
new one, a new band, reset clearances and back in adjustment is bang on for park and third.
For good measure borrowed a buddies Valve body (he doesn't know it yet! LOL)
goes through the gears and starts in N and P so off to try it this week end.

Everything seems fine now with new shift lever and 2nd gear band.
Ran a best ever Saturday of 10.470 @ 128.36 at 90F too but a tail breeze 6.659 1/8 th @ 102.66 60' was 1.481
The re set best ever for this motor sunday
10.451 @ 128.27 with a tail breeze was 90F with worse barometer but may have been a stiffer breeze.
1/8 mile was 6.64 @ 102.71 60' was 1.477
right around 7050 to 7150 when I let off at the end of the quarter (well past) so seem same as my 4000 stall maybe 8% slip???
Thanks for any help that was offered