what am i doing wrong?

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onehellofadart

onehellofadart

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hey guys i need your sugestions, my 1970 dart 340 swinger with my *** in it weighed 3500 lbs on e-town scale at nats. my motor was dyno'd @ 425hp w-35 degree of timeing @6300 rpms. has 3" exhaust. 727 trans rebuilt to stock with 3200 stall converter, and shift kit. i have frame connectors, an 8.75 rear with hvy dty posi unit, 3:91 gears , and mosler axles, caltrac traction bars , and 15" rubber all around. bf goodrich drag radials on rear. also qa-1's in all corners.when i first got her back from shop i put 300 miles on her before going too track. i now have about 600 miles on drive train. 1st time out i stood at tree with revs just high enough too keep plugs clean , about 1000rpm. my shift points were 5400 rpm, best time was 14.832.
at e-town nats first 2 runs tires were @ 15lbs of air and launched at 1000 rpm. best time was 14.333. last run of day i went down too 12 lbs of air and threw a borrowed spare tire in trunk, lef at 1200rpm, launched good and hard.(see 1st photo link in general boards"onehellofadart pics at e-town).ran 13.83. shift points were 5600 rpm, motor pulled smooth all the way down, with nose up.
what am i doing wrong, motor man says i should be doing low 12's. will going too 1500 rpm launch, and shift point of 5800 bring me there? any suggestions will be appriciated, except weight cracks.

tony
 
You should be going much quicker than that.

What's the cam? Why are you shifting at 5400 if the dyno showed max power at 6300? What's the torque & horsepower curve look like?

Does it spin out of the hole? What's your RPM at the finish line? What the MPH?

What does it do at the launch... Does it bog, or do the RPMs climb right up?

With a mild 360 in my Duster, I'm running low 12's. I would think you should be close to that as well.
 
If your HP is at 6300 I see no point in not taking the motor to 6400 to6500 on shifts and 6600 to 7000 in the traps. If you make your 425HP at 6300 you are making less than that at 5400 and 5600. Depending on the cam you could be making as little as 325 at 5400 and 5600.
 
That was my thinking. I wanted to see what cam he had in there, so I could put his combo into Desktop Dyno to see what the horsepower & torque curves looked like, to see where it was making power. And then plug that motor into Desktop Drag to see what it'd run.
 
mikel, and midtex, i'm bringing the rpms up a little each time out. new motor, and drive train lots of cash spent. want to break it in good. haven't gotten trailer yet, though i did sell my vette and bought a dodge p-up too tow it,afraid of long walk home. will get specs on cam when i get home. motor guy told me not too go above 5900 rpm, might be for his own protection. also have dyno print out, but don't know how to get it up on this screen. car launches pretty good no spin, and rpms come up right away, no bog. can't get myself too look at tach going through traps, as much as i tell myself too do so before launch.
tony
 
What cam do you have? And what heads? Ported? Flow numbers?
 
edelbrock performer alum heads opened too max. no flow #'s
don't remember cam. have info at home, at work right now.
 
onehellofadart said:
edelbrock performer alum heads opened too max. no flow #'s
don't remember cam. have info at home, at work right now.
Click to expand...

Do you know any of the cam specs? 450 lift? 508 lift? Long/short duration? If you give me something to go on I can plug it into Desktop Dyno and see what it has to say.
 
no i don't . will post them tonight when i get home. what rpms would you like off dyno sheet if i can't post sheet.
 
onehellofadart said:
no i don't . will post them tonight when i get home. what rpms would you like off dyno sheet if i can't post sheet.
Click to expand...
Cam specs, head specs, valve size (intake/exhaust), compression, piston type, carb cfm, intake type, exhaust type (header tube size, mufflers, etc).

The more information you've got, the better.
 
ok mikel here goes.

comp. cam hyd intake .488 exhaust .491,
duration intake 230, exhaust 236.

heads: edlebrock rpm performer alum. 2.02 intake ,1.6 exhaust
ported , and polished . all opened too max and
portmatched . intake mani to head intake to exhaust to
headers.don't know flow

intake mani : edelbrock ld340

compression: 10.5:1

piston: je

rings: hand filed .040

carb: davinci 860(so i'm told. find no marks except 7915 on bowl).

exhaust: hooker jet hot coated in and out 1.69 tubes to 3" exhaust into
flowmaster 40's

trans: 727

torque conv: 10" 3000 stall

rear: 8 3/4 w hvy posi unit, 3:91's mosler axles

tires: front, 185/65/15 kuhmos , rear bfgoodrich drag
radials 235/60/15

dyno results: this the 3rd pull out of six, can't find 4,5 &
6 which had the 425hp results.
3500rpm 357.1 tq, 238hp
4500rpm 403.7 tq 345.9hp
5000rpm 391.3 tq 372.5hp
5500rpm 378.8 tq 396.6hp
6000rpm 356.3 tq 407.0hp
6200rpm 350.7 tq 414.0hp
6500rpm 317.2 tq 392.5hp
this was dyno'd with a 700 holley

timing: 35

hope i gave you enough info.

tony
 
motor guy told me not too go above 5900 rpm, might be for his own protection. also have dyno print out,
Click to expand...

Seems odd that he flogged it on the engine dyno, but doesn't want you to do the same in the car. How much total running time do you have on this engine? Are the rings seated, or can you tell?
 
I don't want to see you kill the motor but I take my 3/4 ton tow truck to 5500 when I jump on it. It's power is at 3000. If you take it easy nine out of ten passes who is to say it wont beak on the tenth. If it was my car I would at least take it two 6300 to 6500. Do it near your house from about 3000 rolling. If it breaks it breaks. I dont think it will. You have good parts and unless the builder messed something up I don't see an issue. Breaking in a motor is not a 100+mile proccess. The half an hour between 1500 to 3000 works just fine. I am sure later on tonight you will hear from a lot of people that have spun weaker motors in the 6k range. Tose heads like rpm. I dont want to lead you wrong here but I don't think I am that far off.
 
If you were getting 425hp @ 6300rpm, you should be spinning that thing to 6300rpm at the track. If it blows up at that rpm, then you need to go and talk to the engine builder. Even a 4 sec dragsters not going to run in the 4's if they only run it 6000rpm.
 
midtex,and hawaii, that is why i posted this thread. i wanted too hear opinions. did you see where i said it was loseing torque, and hp over 6200rpm. is this normal? if i'm loseing tq, and hp doesn't mean i'm out of my power range? won't she start breaking up?
 
i have a feeling it is realy a 760 davinci. he said 860 and miss placed receipt.
if he dyno'd it with a 700 holly , why would he jump too a 860?
it starts easy, does not bog, it gets up and goes. pulls all the way through.
 
If you dyno'd your engine and it showed peak hp at 6300, your engine should have no problem running at that rpm. The peak is where everything is running optimum thats why it will start falling off past that. This is a normal condition. As long as all the parts you used to build the engine are rated for that rpm, you will not have a problem. In a basically stock 340, 6300rpm should not be a problem as long as the valve springs are matched to the cam you are using so you don't float the valves. If your peak hp was at 6300rpm and your engine builder told you not to spin it past 5900rpm, you should ask him why because if the engine was built right there shouldn't be a problem.
 
he said don't go over 5900 for fear of floating a valve. i've been out of the sport for around 30 years. prob thought i couldn't react fast enough too shift light.
 
Well if you're confident of your driving ability, go out there and let her rip :D Set your shift light to 6000 if you want to practice first or if you have a rev limiter set it to 6500. Just to be certain I'd ask him if the springs came in a kit with the cam, if not what are the specs of the springs he used and specs he installed them at. At least you'll have a little more peace of mind when you're out there racing.
 
its a comp cam with comp springs. all matched. i planned on going too 5900 rpm next time out. i'll go for 6000 instead. again though, the dyno sheet says i'm loseing hp and tq over 6200, if so will it still pull, or will it start too break up?
 
It'll pull strong up to whatever the dyno showed as the peak hp. You should be a little above that going thru the traps. You might even want to try shifting it a little higher and check your timeslips. Try going up a 100rpm and see what it does for your et. The dyno tells you what the engine will do by itself on a stand, once its in your car you have all kinds of other variables that will affect your et. Thats where the engine and chassis tuning comes in :roll:
 
Ok... Assuming the cam is installed straight up, and using stock Edelbrock flow numbers, you should be launching at 3000, shifting at 6300, running 12.34 @ 110 MPH.

That's just a quick run through Desktop Dyno/Drag. I can tune it a little later tonight to get more exact. DD says max HP is 381 @ 6000, tq is 377 @ 4500.
 
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