racing my 66 Comet

[Posi67]

First rule of running tubes in your Slicks is "don't run tubes". if you insist the rim screws are a must as you've found out. The tire will turn and tear off the valve stem. I've never run tubes and normally my tires turn about an inch then stop. Swap side to side and it goes back where I started. This isn't gospel and I'm convinced the type/brand of wheel makes a difference.

That aside, congrats on getting out and making some runs. Some work on the 60' times and I think you'll be having fun. I don't/won't run 1/8th mile so it will be interesting to see how the car runs full 1/4. 

[Stangman]

Hey Posi 67 just curious as to why you wont run 1/8 mile? Dont want to hyjack post.

[gt350hr]

  Jim,
    The 60 and MPH are better than the ET which "I" feel is off by about .3. My idea is it's "laying down" after the launch , but the horsepower is strong enough to run good MPH.
   Posi67 is right about tubes. I have 10x28 Goodyears and haven't run tubes for over twenty years. My car likes 14-15psi and "I" don't use screws . My 1.48-1.50 60s haven't shown any slippage on the rim , something I check every time I look at the air pressure in the tires.
   Not bad times for the heat ( 2-3 tenths quicker in cooler weather for sure).
  Randy

[Jim Comet]

We had rev limit and shift point issues on all runs. Our shifts were off by 500 plus rpm's and we were bouncing off the rev limiter which we were unable to raise above 6500 rpms. I am pretty sure that when I fix these, it will run consistent low sevens.

[gt350hr]

  Agreed now that I see what you were fighting! Good luck , it will go faster with a few more tweaks.

[57 lima bean]

The M/T 28.5's will be coming your way on 8 inch wheels (4/4) ....

[Jim Comet]

Well we figured out the shift light, rev limit and 2 step today. I also installed a one wire 140 amp alternator so no more charging issues either. Here is a time slip with the numbers (car #115). Jim

[Stangman]

Nice!!! Your really starightning things out.

[WerbyFord]

Great story with a great timeslip. Once again I missed the prediction - spending too much time Gonkulating NHRA history on HAMB.
So many Mouse combinations, all the NHRA nationals ended up infested with rodents.

First I had to hunt for the engine link, I forgot all about having already read it. Too much going on.
http://fepower.net/simplemachinesforum/index.php?topic=7119.0;all

On your 1st runs (July 27) the comment about the car laying down seems just right per the Gonkulator - good 60ft, good 1/8 MPH, slow 1/8 ET.
Gonkulator said about 7.10 ET. I used an extra full second on the 1-2 shift and that brought things in line, likely not what really happened but somewhere around the 1-2 shift the car fell asleep and then woke up again.
I calculated a DA=2643 ft on your July 27 runs, or about 95% power vs the typical weather I assume in the Gonkulator.

On your next runs (Aug 10) I had to have everything about "right on" in the Gonkulator and then things lined up pretty good:
1.48
4.41
6.89 at 98.6
10.88 at 122.97 (or 123.89mph measured the "old way").
I get a DA=2046 ft for that day, or abou 97% power vs a typical Gonkulator run.

SAE Gross Sea Level Air (ok stop laughing everybody) is about 4% better than what I use for Gonkulator air or about 7% better than the air you had. Here is what the Gonkulator gets for your car on an SAE Day if you can ever find one:
1.46
4.32
6.75 at 100.6
10.66 at 125.4 (or 126.4 out the back door)
A Magazine-Worthy story for sure.


NOTE: "Gonkulator Air" as I normally use is my guess for my 1st trip to Milan back in 1975:
64 F
50% RH
29.92 Barometer
500 ft elevation
1000 ft DA
100% Power (I like to think of air in terms of %Power instead of DA, so an SAE Day is 104% Power, Jim's day above is 97% Power, etc. Since 3% power is about 1% trap speed, it makes the conversions pretty easy.)
Funny I remember that 1st trip to Milan like yesterday, a little chilly crawling under the car on the entry road in the morning to unbolt the headers, cold enough my girlfriend stayed in the car to keep warm and fell asleep (she woke up in a hurry). Nice day later on, I didn't get hot so I know it was in the 60s.
About the best Michigan Summer race weather you could hope for.
So when I give a generic "gonkulator result" unless I know the track & weather, that's what I'm using.

[gt350hr]

 Nice going Jim matches what I suggested in reply #9. Cooler weather later in the year could be worth a couple more tenths , getting you closer to my original 6.60s ( 1/8th) prediction.

[Stangman]

Or my 6.78. 

[BattlestarGalactic]

Glad to see you got it working well!  The 1/8 and 1/4 numbers are very in line.  Nice 60ft.

[Jim Comet]

My son is shifting @ 6700 rpm. Based on the dyno info, it would probably run faster if he were to shift @7100-7200rpm but I am still getting used to spinning a motor this high. Jim

[e philpott]

Reply #2 my 6.9? at 102 if it hooks , lol

[BattlestarGalactic]

Nobody but you can decide at what to shift it at.  If you want to do fast, shift it higher.  If you are happy with it...shift it at 6700.