Took my car to the strip today and really had no ideal what to expect, but figured I would run some mid 7's and maybe 2 second 60's. This is in a backhalfed 70 Chevelle that weighs I'm guessing 3400 lbs.

1st pass no time slip but dead hooked
2nd pass 1.38 6.92 92.11
3rd pass 1.35 6.90 94.79
4th pass 1.41 6.95 95.92
5th pass 1.53 7.98 63.70 engine misfired whole run?
6th pass 1.54 7.15 96.01

The first three passes I was on the rev limiter ( 6500rpm) 50 yards before the finish line. I turned the limiter up to 7000rpm and was going through the traps at 6900rpm which helped mph but my sixtys fell way off, I think the track just went away on me.

The suspension hasn't been touched, 4 link settings are just as the directions tell you for first time. Coilover spanner nuts were only hand tight and the slicks I used were my buddies throw aways. To say the least I'm estatic about the 60 ft times. Here's the combo;

468 12.5:1
990 heads 2.25 in. 1.88 ex.
402A6LUN 612 in. 630 ex 255* in. 263* ex on 104 centers
Victor single plane ( oval)
1050 dominator
400 turbo
514 rear

wow...good numbers...strange...but good. I run 1.56 60 foot with 7.02 at 97 MPH in the 1/8th

I think the track needs to check their 60ft timers, nothing against you but you're not making enough power (shown by 1/8th mille e.t./mph) to 60ft that quick.

I dunno . . . I would personally expect more like a 1.45 sixty with that ET, but maybe with 5.14 gears and the right converter it could be done. Especially if his MPH is off due to a misfire or rev limiter on the top end.

Too much RPM in the traps for the cam. That's my $.02. 60' is good cause of the gear.

I think the results are very believable. Guys, he has a back halved car with 5.14 gears and probably a decent size of slicks. So, bang off the line, then have to drag those high friction tires all the way down the track. Too few passes to know for sure, but if the higher mph pass was with spin off the line then that would explain both the slow 60' and the higher mph. The times in my signature were off a tire spinning 1.6x 60' time with 8.9" tread width E.T. Streets. I want the 1.3x 60' times, but without the extra drag of wide slicks on a back half car.

Thomas

Hey Bob, lets be optimistic here maybe the finish line timers were off. Did I mention I was shallowed staged? Just kidding, This is the first time I've set foot in a drag car so my knowledge of E.T. slips is limited. I do know the mph and et are slow for that 60 ft. Here is the 330 ft time on the quickest pass maybe it will shed some light.

1.35 60ft 4.343 330ft

My buddy raced at this track Friday night and had his quickest 60ft, his normal 60 is around 1.45, he ran a 1.41 but in very good air so I'd say the lights were pretty close Friday.

I will say the car seems to fall off a little once I get passed half way. I really don't want to turn this engine much over 6500rpm, would a 4.88 gear change improve the top end yet still 60ft good? Ken

mph does not vary much whether you hook or spin, 4 passes from friday night:

1.415-4.239-6.65@101.95-8.74@115.56--" rear QA1's set at 6/12 clicks

1.408-4.214-6.62@101.81-8.71@115.95--" stiffened the shocks 2 clicks

1.634-4.553-6.98@101.51-9.08@115.41-10.80@116.52 went full stiff and spun the tires, didnt know they left 1/4 mile timers on.

1.410-4.229-6.63@102.09-8.73@115.83-10.409@125.24-

pass number 3 the 60ft was off by over 2 tenths, yet mph stayed the same.

A friend of mine just swapped from 4.11's to 4.88's this week, 33x10.5x15 slick, 60fts dropped from 1.43-1.45 to 1.40-1.42, his car (3300lbs Malibu) is about a tenth quicker than mine, runs 6.5x @ 102-103 mph 1/8th.

Okay, apparently Bob doesn't want to cut you any slack and all passes should have the about the same mph. If you were very experienced I might not expect so much mph variation, but otherwise I've seen plenty of guys get results just like Ken, with cars that were still in the process of getting dialed in.

Tell us more, like the size of slicks.

Thomas

I dont think you'd see much difference between 4.88's and 5.14's. I don't mean to give you a hard time, just seems way outta whack to me :confused: Got any pics of the launch? What size tires? What converter? It must be way too loose to be turning those rpms in the 1/8th. I've never run steeper gears than 4.11's.

That seems a little quick in the 60' to me also, none the less I am sure the car is fun.

That seems a little quick in the 60' to me also, none the less I am sure the car is fun. I think with that much gear everything seems to line up. The converter slippage seems unusually high, how tall are the slicks? Going back to around 4.56 gears should drop your RPM a fair amount but 4.88s won't help much. You might have to change converters to get all the way down a quarter mile or go back to 4.10 gears.

As a couple of others have said ... nothing wrong with that 60', ET and MPH. The car just leaves like a rocket ... And no offense ment by any means but it just doesnt make the power to carry it on down the track. Look at that MPH for that ET .. really low wouldnt you say ? thats what tells you it left great

it's always good to get out and make some initial shakedown runs and not have any serious issues to contend with.

Given your engine combination, I'll take a WAG and say your engine should be in the 575-625 hp range once fully tuned. That kind of power in a 3400 lb car (w/driver) has the potential to run low 10's in the 1/4 mile which would be 6.40's to 6.50's in the 1/8 mile.

I too am curious why the 60's and ET's/mph don't match up.

What area are you from and what track where the runs made at?

it's always good to get out and make some initial shakedown runs and not have any serious issues to contend with.

Given your engine combination, I'll take a WAG and say your engine should be in the 575-625 hp range once fully tuned. That kind of power in a 3400 lb car (w/driver) has the potential to run low 10's in the 1/4 mile which would be 6.40's to 6.50's in the 1/8 mile.

I too am curious why the 60's and ET's/mph don't match up.

What area are you from and what track where the runs made at? Over on a truck site i saw a '75 short bed that had been lightened quite a bit, had a high powered blower motor and fairly steep gears which reportedly ran a 1.00 sixty foot. So freaks do occasionally happen. The truck ran a quarter mile of mid 8.40s @ 163 MPH so it must have had a little too much gear in it and a monster motor. I think i remember it being a big inch small block. P.S.... After studying the claimed time slips i'm kind off skeptical as to the claims as two of the fast trucks eighth mile speeds look way to slow for the E.T.s they posted. Any vehicle capable or low five second eight miles should be traveling near 140 at the eight mile clocks and two of the faster trucks are showing only 122-123 MPH with quarter mile speeds in the mid 160s. Don't think i buy a 44 MPH gain in the second eighth.

I do think the car is way down on power. When I first got this car running it would destroy the tires when shifting into high gear to the point I had to lift or clean out some ditches. All at once it wasn't spinning at all in high gear and with the ole assmeter I could feel the difference. I took the car to a chasis dyno where it peaked out at 304 hp and 340 ft. lb torque, I knew for sure at that point something was wrong.

Since then I've checked (this gets lengthy here) compression, valve lash, timing, fuel pressure, carb, distributor. I've replaced plugs, plug wires, coil, ignition box, fuel pump and anything else aside from taking the engine apart and have found nothing wrong.

So now I'm thinking it can't be the engine then move on to convertor, trans, rearend. Pull new convertor out and have it cut apart, says he can find nothing wrong. Take fresh transmission back to the builder and tell have pull it apart again and checked everything, nothing. I pull rear gears for the fun of it and everything looks fine.

The thing about all of this is the engine runs flawless, no misfires or bogging.
I finally decided to take it to the track and just see what it would do, I really expected it to run in the mid 7s because this engine just felt weak up top. I was very suprised it ran in the 6s first time down and couldn't believe the 60 ft. times.

After I've had time to think about I can't help but believe the convertor is slipping alot. Both my buddies run 513 gears in they're sbf and only turn they're engines around 6200-6300 and they're mph is right at 100. I'm turning 6900rpm and my best mph was 96. My tires are 29.5x13.5 I think that comes to 92.6 inches in circumference, can someone figure the amount of slippage? Ken

I live in Tennessee in between Knoxville and Chattanooga. These runs were made in Maryville TN. at the 411 Dragstrip.

I almost forgot the convertor will footbrake to 3400 and flash to 5500, it's pretty loose. Ken

Over on a truck site i saw a '75 short bed that had been lightened quite a bit, had a high powered blower motor and fairly steep gears which reportedly ran a 1.00 sixty foot. So freaks do occasionally happen. The truck ran a quarter mile of mid 8.40s @ 163 MPH so it must have had a little too much gear in it and a monster motor. I think i remember it being a big inch small block.

No way that truck went 1.00 60' and then only an 8.40 in the 1/4 no way in he!!

No way that truck went 1.00 60' and then only an 8.40 in the 1/4 no way in he!!

my friend's plymouth runs mid 8s (depending on which track) and 1.0 sixties. IT CAN BE DONE

Hmm, could I be wrong ?? damn not again. A plymouth? 1.0 60'..... no I am not wrong.

I have never seen anything like it, but I guess stranger things have heppended.

No way that truck went 1.00 60' and then only an 8.40 in the 1/4 no way in he!! The truck that i was thinking about is over on Dragtruk.com. It was the second one owned by a Kelly Perkins and only weighes 2300 lbs., has a fiberglass body and is one of three in the 1.0 range. Believe it or not !!! My son's car won't do it either but does weigh 3560 lbs. I saw a low nine second Vega that was unusually fast for the first sixty feet but don't remember what it ran right now.

After checking some responses I called to make sure. Turns out I stand corrected! It was 1.26, further making harold's sight more rare!

Okay, time for the math:

Theoretical "no slip" speed
With no tire growth; (6,900 x 29.5 x 2.96)/(5.14 x 1,000) = 117.22 mph
With 1" tire growth; (6,900 x 30.5 x 2.96)/(5.14 x 1,000) = 121.19 mph

vs. Actual 96.01 mph

Which leaves you somewhere in the 18.1% to 20.78% rpm loss.

Given that the trans and converter checked out good my next suspect would be an over optimistic tachometer. I think it is quite possible that you are not turning the rpms that you see on the tach. Lacking that I would be looking at the converter and trans again.

Thomas

Okay, time for the math:

Theoretical "no slip" speed
With no tire growth; (6,900 x 29.5 x 2.96)/(5.14 x 1,000) = 117.22 mph
With 1" tire growth; (6,900 x 30.5 x 2.96)/(5.14 x 1,000) = 121.19 mph

vs. Actual 96.01 mph

Which leaves you somewhere in the 18.1% to 20.78% rpm loss.

Given that the trans and converter checked out good my next suspect would be an over optimistic tachometer. I think it is quite possible that you are not turning the rpms that you see on the tach. Lacking that I would be looking at the converter and trans again.

Thomas I'd think the converter is way messed up. 96 MPH while running 5.14 gears should only be running 5650 RPM instead of 6900 with a 29.5" tire. I would also think you must have a fuel delivery problem to have gone from roasting the tires to laying over at speed and showing such low numbers on the chassis dyno. You might be spinning on the rollers which sometimes happens if the tires aren't inflated enough. I also don't know how those people who checked your converter could have declared it to be O.K. as it is slipping over 18%, that is not O.K. in anybodies book. Our loose 8" converter only had about 10-11% slippage until we overpowered it with nitrous. You could also change tachs to check yours. What did the dynojets tach show? Have another converter company look at that converter as it is not working like it should be.

I always like to emphasize the potentially easy to fix problems first - please change out your tach with a known good one to see if the rpms change. Alternatively check it against a fancy timing light that has a digital readout of rpms.

After that Harold is probably right that it is your torque converter letting you down.

Thomas

provell, she is diffently hooking and with that sixty foot i would be thinking 6.50s in the 1/8th but the mph is about right for 7.0s .we got the new engine in and sunday we went and run to see if everything was okay and see what it was gonna do .67 nova 2880 before the cage was put in. 456 gears and 28 x10 slicks 60ft 1.501 330 4.449 1/8 6.945 mph .098.00 second pass 60ft 1.500 330 4.451 1/8 6.944 mph 98.13 third pass 60ft 1.55 330 4.499 1/8 7.000 mph 97.84 as you can see our 60fts are off some due to track conditions test and tune track.and no race at all this week due to bracket finnals in jackson s.c.our 60fts are any where from my best of 1.44 to 1.48 due to the track.hopefully sat .night it will run some 6.80s .just my guess as some others it may be your fuel pressure it happen to me once and burnt a piston from being lean .really didnt find it till the pump quit and put a new one on

i have my shift lite set at 6200 and it also comes on just before the traps if thats any help to you

Thanks guys for the input. The shift light is set at 6000 rpm and comes on the instant the tach reaches 6000 rpm so its good at that point. The shift light also gets its readings from the ignition box and not the tach, but I do have another tach I could try.

The converter would seem to be more logical since the et,s are so far off. Is there anyway to theoretically figure how the car would run with a converter that only slipped 8%-10%, if there was and that time was close to what the car should run based on the 60ft time, then we would know for sure it is the converter. The converter I'm using is not a brand name just a guy thats very popular with the drag racers and seems to have a good reputation.

Harold, funny you should mention a fuel delivery problem. When the car seemed to have lost all it's power I had change fuel pumps. It had a cheap Procomp on it that was still working fine but was leaking fuel between the motor and pump. I replaced it with a Holley black pump and also several different regulators before I got the fuel pressures to stabilize. The car never seemed to run the same after this swap. This prompted me to put a fuel gauge inside the car so I could watch the pressures while driving down the road. I'm pulling my pressures straight off the rear bowl and the fuel pressure never drops below 7lbs. It also has 1/2" fuel lines from tank to carb. I've also took the carb apart to make sure nothing had got sucked into it during the swap. I thought for the longest time it was something in the fuel system but if its keeping a constant 7 lbs of pressure in the bowls it must be working correct. Ken