car slowing between first two rounds ?

[d2racer]

now i know all or most cars fall off between the first pass and all the rest

most of my cars , almost all mopars , have fallen off between .02 and .03 from the first to second pass depending on heat etc.

but my stang seems to fall off .08 religiously no matter what i do , does not matter weather , track , time of dy etc.... if the first pass is an .01 the second will be a .09

it will then run the slower number consistently the rest of the event ?
tried different carbs , ign and timing

mild cammed 302 , dynamic c-4 , 410 spool , good consistent 60 ft

only thing i can think of offhand is it has a big converter built for a fast 8sec pro car , supposed to stall at 5500 in his car , it was free so i use it , it launches at 3200 in my car and mile an hours okay for my combo , 12.04 at 111 , and when i try smaller converters the car slows down so i always put it back

but maybe when its hot and the fluid thins it slips more ?? mile an hour stays consistent but its driving me crazy

any ideas?????

[jays64II]

i dunno Tony. in most cases i've always picked up because all the fluids are warmer/thinner. are you warming it up by driving it around and gettin everything good and warm? Do ya have a weather station? any big differences in DA or such ?

[d2racer]

yea , i always cruise around a while , run it thru the gears , always have , every car.

and this has been going on all year , every event , all weather , any time off day

its always exactly .08 too not 7 or 6

even had a bracket event where we had one time shot , dialed .08 slower first round and ran dead on with a 1 !!!!

but it sucks for 12.0 qualifying .

just wierd and annoying , got me scratching my head

gonna try to get a track day and play with timing maybe

maybe put synthetic oil in the rear?

[Gameracing]

Does the MPH fall off also or just lose ET, look at your short times, subtract to get incrementals, you'll see where it is

[jays64II]

what george said. look at the increments and see where the difference is coming from. if you lose .04 in the 60' or the 1/8 it will be .08 at the traps

[d2racer]

okay , i checked my records last 4 times out and it's pretty consistent at least ?

it falls off ;

60 ft --.02
330ft--.05
660-1/8th- .06
and all done by the 1000 at a drop of .08

just think that too much of a drop from first to second pass , and then it will run dead on that number , give or take .01 depending on weather , for the rest of the night .

never had any of my mopars drop that much , and not sure what , if anything i can do about it .

temp diff on the line is only about 10 degrees , maybe get it hotter before that first pass ?.
no thermostat , just a restrictor plate

[Gameracing]

Try putting a heat insulating spacer between carb and manifold

[jays64II]

damn george ! i was gonna say to put a 1/2" 4 hole-er on there myself. ya beeat me to it !

[tire fryer]

Go back to the MoPar's

[Road Runner Kev]

Go back to the MoPar's

I AGREE!!!


Tony if I had to guess I'd say it was a trany problem. Sounds like when it gets hot it slips more at the line. A loss of .o2 at the 60' can easily add up to .08 at the stripe. Maybe converter or your rear end clutches slipping too. If engine temps are the same or even slightly hotter car should be consistent unless you are letting it cool down 10 degrees from your first pass. My car makes the most power @ 195-200 water and oil temp, @ 180 water it is .10 slower.

[d2racer]

damn Kev , i knew it was gonna happen , i signed a contract on dads condo this afternoon , ran home and called CJ- they sold the trailer yesterday !!!!

maybe the guys backs out???

[Road Runner Kev]

Damn Tony that sucks! Hey now you know how I feel about your Dodge. Karma's a bitch ... ain't it!

Glad you got a contract, I know that was weighing on you.

Did you ever get to do any more tuning on the new carb?

BTW, Dave and CJ "taged" my trailer at the last race. I like it though so it's gonna stay LOL.

[d2racer]

Damn Tony that sucks! Hey now you know how I feel about your Dodge. Karma's a bitch ... ain't it!

Glad you got a contract, I know that was weighing on you.

Did you ever get to do any more tuning on the new carb?

BTW, Dave and CJ "taged" my trailer at the last race. I like it though so it's gonna stay LOL.

ha! yea they tagged me too and its staying lol

no tuning yet , bee too busy to get out , maybe fri nite . you gonna be at outlaws on the 6th for 12.0???

[Road Runner Kev]

hell yea I'll be there!

[Leakygasket]

if you run a msd box with no alternator
and run only on battery
and dont charge it between rounds
you will slow down.
if you run msd box and an alternator
use an extra voltage regulator and wire it directly to the msd box only.
If temps at the line are the same every run and it still does it buy the biggest trans cooler you can.

[botmbulb]

I have 3 questions: Is the car trailered? Does it have an electric water pump/drive, or is it crank driven? Does it have aluminum heads?

[d2racer]

yes its trailered , yes it has aluminum heads , it still has the stock water pump and pulleys .
have not been out last 3 weeks to test yet since the one outing with the new carb .
want to see if its still as consistent hot now that i made it richer

i suspect the trans fluid or converter , just wierd how it will drop exactly .08 from first to second shot then run that number , +or- .01 all nite

[adamsvega]

the test will be to power brake it with the engine cold on and off to get the trans hot but not the carb and intake /fuel before the first pass to test the trans (i doubt it, if its that ya loose each pass ) next you can warm it up on a jack to the return road temps . and eliminate that first good pass. what type of boosters and manfold do you have . ???? you might want to give it the glass half full approach and see why it picks up cold !! a fuel line insulation (return?) trans temp is too hot ??? need a rear fanned cooler and long alum lines .
carb getting hot needs a insulating spacer and some tuning ... dist. timing weights /advance sticks hot . dual plane intake with no air gap will heat up with oil temp !!!

[d2racer]

its got an air gap manifold , and i drive it aropund the pits for 15 mins or so running it thru the gears but i never beat on the trans before first round so maybe ?

i switched from a 650 demon to a pro-systems 750 holley with annular boosters , first time out it was .12 quicker but still fell off .08 to second round then held that number
i went up 2 sizes on jets and the car picked up .04 and is consistent and only fell off .04 from first to second round then ran that number 2 more rounds

i can live with that but i'm gonna try really heating the trans next time out

[adamsvega]

You gonna have to tune a air gap like it is a sigle plane .. i would warm up the thing on jacks cycling rpm,gear and the water pump till you got it over the temp that you come back the return road and see if it gets rid of the cold /manifold problem .