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Old 07-23-2003, 01:03 PM
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Launching a car.

My camaro seems to launch wierd. (BTW i have exhaust appointment next week) its off the headers atm, i dont drive it much atm. ANYWAYS its got a Th350 with shift kit and 3.73 limited slip,and a 2200-2600 stall convertor. If i rev the car up to the point just before i spin tires and let off the brake and mash it, it takes off pretty hard but then at like 30 it plants you in you seat even more, why is this? I thought it would pull real hard from the take off, or is it cause of the stall convertor? Maybe im just spinning and cant tell, cause the car is so loud? Like i said it pulls real hard taking off but once i hit 30 it will plant you arse back even more.

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Old 07-23-2003, 02:05 PM
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I would check my carburetor tune to start with. Sounds like you are running a double pumper or vac secondary carb with too light a spring. Either way, your carb is too big in the beginning of your launch and is losing it's signal to suck gas from the venturis. Once your speed increases, the gas begins to flow and it kicks up the power output.
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Old 07-23-2003, 09:50 PM
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Its a Edelbrock 600cfm, it sh9ould be in tune, i just thought it MIGHT have been the car getting into peak trq or something.
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Old 07-24-2003, 01:05 AM
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Man, my setup is so similar to Rubberman's it's crazy! I have the same setup, but 3.08's in the rear (70 nova), and it does the same thing! I have the same carb also, where would this spring be in the carb, and where can I find the spring that I would need?


I thought that it was just hitting it's stall point where it stops slipping......
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Old 07-24-2003, 04:18 AM
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Never launched a car, but here at the plant, you should see when a Freightliner Century Class Rig jumps the rollers on the dyno and breaks the chains. There isn't a dry pair of skivvies in the house!
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Old 07-24-2003, 06:26 AM
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man that would be scary
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Old 07-24-2003, 06:44 AM
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Everytime your car gets to it's stall point. A stall point is the rpm's that the motor can safely turn before stalling out the car, thus stall speed.

Hi-Stall speed converters don't just help you on the launch, If were running something like a 3000 stall everytime that you would need to speed up a little bit & were doing under 3000 rpm's the Torque converter would speed up & grab at it's stall point. So you might get some "Grabby" sensations.

Also starting off on steep hills with really loose stalls is fun too. The stall you are talking about is really almost stock, I bet that thing isn't 800 rpm's past the stock stall speed.
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Old 07-24-2003, 08:07 AM
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They told me that the stall speed of the stock convertor that came with the tranny was like 1300 or so, this one (before my tach broke) was stalling around 2500 or so, but yeah its not real high.
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Old 07-24-2003, 08:53 AM
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Quote:
Originally posted by Adrenaline_Fiend
Man, my setup is so similar to Rubberman's it's crazy! I have the same setup, but 3.08's in the rear (70 nova), and it does the same thing! I have the same carb also, where would this spring be in the carb, and where can I find the spring that I would need?


I thought that it was just hitting it's stall point where it stops slipping......
I really don't think it is the torque converter 'kicking in'. They slip more than a stock converter but there shouldn't be any 'jump' in their operating range.

My comments were based on a Holley carb with vacuum secondaries. The Edelbrock uses mechanical secondaries with an air flow actuated flapper valve. Secondaries only open when air flow pressing on the flapper valve overcomes a counter balance weight. Principle of your problem is the same, some part of your carb is not flowing gas very well in the bogging transition period. There isn't much published on tuning Edelbrocks and I have only worked on one before and we got it going pretty well with a couple changes of rods and jets. Here is a web site that appears to give a lot of useful tuning info. See if they tell you anything that will help.

http://www.telusplanet.net/public/gi...delbrock_1.htm
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Old 07-24-2003, 09:24 AM
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Sounds to me like at 30 MPH your engine is just starting into its "power curve." The power curve of an engine is where it starts its optimal output of power based on engine RPM's, your carburetor, rear end gearing, tire size, octane of the fuel you are using, etc, etc. It will stay running really strong through the power curve until it reaches the "other side" of the power curve, then it will begin losing power, but not RPM's. If you look at any dyno readout, you will see what I am writing about.

Benji
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Old 07-24-2003, 10:20 AM
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Have you ever noticed what rpm you are in when you feel the extra torque kick in? I could see it also being that the tires are spinning since you say you smash the throttle right off the line. When I launch, I do exactly what you say at stop, but when I release the brake, I give it gas smooth and graudually (it's still pretty quick though). Smashing the throttle will cause wheel spin off the line.
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Old 07-24-2003, 12:16 PM
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i think if you cant hear then you probably are smokin the tires, but i think it's also what benji is saying, that you are just getting into the cam's powerband.
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Old 07-25-2003, 01:56 AM
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My engine seems to have the least power from about 1800-3000 rpm's. At 3000 it has it's best power.
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Old 07-26-2003, 03:25 AM
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im not sure what model your camaro is but if its a 3rd gen then ive had the same problem. it wasnt in my carb(i run EFI) it was my stok rear suspesion. the stock suspension on any of the 3rd gens that i have ever owned have been some of the worst for deflecting under torque-its not that their set up wrong it s more that things back their flex very easily. i always thought of suspension upgrades to be for the people with monster power but about 2 years ago i learned the difference. what would happen is i would launch the car and at around 30-35mph my car felt like it just received a shot of NOS. i thought it the power band so i spent a long while messing with my ecu(i got a programmable FPP unit) but this didnt help. i then had a friend stand outside the car and watch the right rear tire. from his observation we learned that the right rear was moving almost 2inches forward inside the wheel well. since i still had stock suspension my first mod for the fix was poly..bushings. these helped keep the geometry correct but i was still having problems after that. something in their was bending--WOW is the first thing i thought. i didnt really think that street driven cars could launch hard enuff to bend the heavy metal suspension peices. i didnt want to spend alot of money on expensive suspension parts so i just droped the stock peices and did some welding to stiffin them up.---the problem was cured

if you want info on where to weld some metal to stiffen the stuff up email me at 25thferret@sbcglobal.net-ill be happy to helpout a fellow f-body lover
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