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#1
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I have a '73 charger with a hi-po 400in it. it doesn't move off the line but once the rpms go up the engine really kicks in. i have set the carbeurator back in case it was running too rich. this did not fix the problem. The exhaust no longer smells like gas, and i still have this problem. when i hit the gas at 15-20 or 60-70 mph the car does not hesitate at all. the secondaries kick right in and it takes off.
Just to illustrate this problem, my friend has g-tech, and we ran my car. It ran the 1/4 mile in 15.73 s @ 99.1 mph. And the 0-60 time was 7.24 s. Does anyone have a diagnosis for this hindering problem? |
#2
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HEY CHARGER NOT ENOUGH INFO. WHAT GEARS DO YOU HAVE AND WHAT CARB , MANUAL OR VAC. SECONDARIES ?SOUNDS LIKE YOU HAVE HIGHWAY GEARS (3.23) AND TOO MUCH CARB TOO SOON FOR THIS HEAVY OF A CAR. POST YOUR INFO AND I'LL CHECK BACK...PRO...(UGLY AS U BUT FASTER 2)
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#3
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We need more information, you could have too tall of gears, vaccum advance not working, partially clogged exhaust, or the wrong exhaust, to much carb., a bad torque convertor, all kinds of things can cause what is happening to your rig. Get back to us with more info. Thanks and go hard
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#4
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Most likely your compression ratio is down. These engines were only factory rated around 8.2 to 8.5 to 1 and actually came in at around 8.0 and usually less. I have actually measured 2 of the stock 400's that were 7.7:1 upon teardown. A low numerically rear end gear ratio will contribute to a real soogy bottom end. Best cure? Get into the short block and raise that cr to about 9.00:1. That makes more sense then adding a set of steep gears to a street driven car
The Old Hippie Hisself |
#5
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the carb is a 750 edelbrock performer series carb pn 1407.the gears are 3.23. the measured cr is 8.5:1. the torque converter is stock, but an 11" tci breakaway 2500 stall converter is on the way.the car is sluggish off the line, but i can't launch it either. there is a 2 second delay off the line. and if i powerbrake it it almost or sometimes does stall.the max i can bring the revs to when launching is 1400 rpms. i myself think it is the converter. what do you think?
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#6
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If you want better take off you will have to lower the gears a bit. 3.55 are good but 3.91's would be better, it will wind a little more on the highway. The new converter will also help a lot.
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#7
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Squad, it is not a rearend problem. Remember when I said I can't launch. This would not be a problem in the rearend.It is either a timing, fuel, or torque converter problem. And if it is the latter it will be prevented soon. The problem is a delay in acceleration, period. It is not that it is just slow out of the hole, it barely moves out of the hole. After the revs get going the car flies. Just look at the 99.1 mph trap speed on a 15.73 1/4 mile time. Does any one have an idea on the diagnosis as far as fuel and timing go? The carbeurator is a vacuum secondary 750 cfm edelbrock carb, part 1407. I have leaned it up a bit.(4 full turns)and that didn't seem to help much.
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#8
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REMEMBER START WITH THE BASICS, WHICH IN YOUR CASE IS VERIFY COMPRESSION, ON A GAUGE YOU SHOULD READ A MINIMUM OF 100 PSI, IF LOWER YOU CANT JET A WORN MOTOR. YOUR 750 IS A GOOD CHOICE BUT I CAN GUARANTEE YOU ITS TOO RICH RIGHT OUT OF THE BOX. I'VE BEEN BUILDING RACE CARS FOR CUSTOMERS FOR 12 YRS. AND JETTING THEM WITH A GAS ANALYZER, BY TURNING YOUR MIXTURE SCREWS YOU ARE EFFECTING MIX BUT NOT IN THE APPROPRIATE MANNER, MIX SCREWS ARE TO BE SET FOR HIGHEST VACCIM READING AT IDLE. SO START HERE TIMING SET TO 10 TO 15 DEGREES INITIAL(AT IDLE) RETARD 2 DEGREES AT A TIME IF YOU HEAR PINGING,IF YOUR TIMING WAS OFF YOU PROBABLY WILL PICK UP A HESISTATION (WHICH YOU MAY ALREADY HAVE)TRY MOVING THE ACCELERATOR PUMP ROD TO A HIGHER HOLE THIS WILL INCREASE YOUR SHOT IF IT BOGS WORSE GO THE OTHER WAY, I IMAGINE YOU'LL NEED TO CHANGE YOUR JETTING, PRIMARIES HAVE .101 DROP TO .98 AND DROP SECONDARY JETS .03 ALSO IF YOU GET SOME IMPROVEMENT BUT STILL SMELLS RICH GO .03 AGAIN REMEMBER IF YOU RUN RICH VERY LONG YOUR PLUGS ARE TRASH DONT CLEAN THEM ..EVER REPLACE THEM THEY WILL MAKE IT IMPOSSIBLE TO JET CORRECTLY.ALSO CHECK FOR VACCUM LEAKS ,COVER PRIMARIES WITH A RAG ABOUT 90% OF THE OPENING AT IDLE IF IT STARTS TO DIE YOUR GOOD IF RPM GOES UP YOU HAVE ALEAK SOMEWHERE. A DECENT RULE OF THUMB FOR CHECKING JETTING IS TO PULL OFF A VACCUM LINE (A LIVE SMALL ONE AT CARB) AND IDLE SPEED SHOULD CHANGE ONLY SLIGHTLY, IF IT GOES UP YOUR TOORICH IF IT STARTS ACTING LIKE ITS MISSING YOUR TOO LEAN.HOPE THIS HELPS POST AGAIN WITH YOUR RESULTS I'LL CHECK BACK...PRO...
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#9
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OH YEAH FORGOT , YOU MAY HAVE A SLOPPY TIMING CHAIN, EASY CHECK,TURN CRANK BY HAND WHILE WATCHING DIST ROTOR THEN THE OPPOSITE WAY IF YOU TURN MORE THAN AN EIGTH TURN ITS JUNK AND CAN CAUSE THIS. HOW MANY MILES ON MOTOR? ..PRO..
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#10
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4 k on the motor
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#11
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You've answered the question yourself, you said that once it's rolling, it flies. You need to check the color of the trans fluid. It sounds as though you have a bad convertor. This would cause a poor launch but would do fine once it is running. Sounds like you have checked every thing else. The stall could also be the problem of the convertor. If someone gave you a truck convertor, lower stall than a car, you would have trouble, and the stall would be about where you said. So go after the convertor. Good luck.
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#12
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I thank all of you for your help, and I will keep you posted after the converter is installed.
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