'72 Chevelle Acceleration Problems
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Teching In
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'72 Chevelle Acceleration Problems Hey guys,
Im new to the forums and at the whole car thing. I dont know much about my car me and my dad just built for me. I have a '72 Chevelle SS 350.
It has been bored out thirty over, holley carbeurator(sp?) unsure what number, cam, roll n rockers, forged flat top pistons, hooker headers, flowmaster exhaust, and real cowl induction hood(has the slit that flips up and sucks in air when you stomp on the gas, but i need to buy a few more parts to get it working right). Its a fresh motor we had built right before we put it into the car. Oh, and it has a low gear in the rear end, a 4-10 i think, if that gear doesnt exist then i dont know what it is, all i know is that when im going 60 mph im turning 2500rpms.
I figured with all that stuff it should be quick atleast. But when I took it for a test drive, i floored it. I noticed my pedal wouldnt go down very far, and it was very very slow. I didnt feel it down shift or kick into the passing gear or anything so i wondering whats wrong. My dad says he doesnt think the carb is opening all the way but i dont think he wants to fix it because he doesnt want me going fast. Also, my friend said something about a kickdown cable or something.
As you can see I dont know jack about cars or anything and my friend is into new stuff so he doesnt know much about the old muscle cars so any help/advice you could give me would be greatly appreciated.
Im new to the forums and at the whole car thing. I dont know much about my car me and my dad just built for me. I have a '72 Chevelle SS 350.
It has been bored out thirty over, holley carbeurator(sp?) unsure what number, cam, roll n rockers, forged flat top pistons, hooker headers, flowmaster exhaust, and real cowl induction hood(has the slit that flips up and sucks in air when you stomp on the gas, but i need to buy a few more parts to get it working right). Its a fresh motor we had built right before we put it into the car. Oh, and it has a low gear in the rear end, a 4-10 i think, if that gear doesnt exist then i dont know what it is, all i know is that when im going 60 mph im turning 2500rpms.
I figured with all that stuff it should be quick atleast. But when I took it for a test drive, i floored it. I noticed my pedal wouldnt go down very far, and it was very very slow. I didnt feel it down shift or kick into the passing gear or anything so i wondering whats wrong. My dad says he doesnt think the carb is opening all the way but i dont think he wants to fix it because he doesnt want me going fast. Also, my friend said something about a kickdown cable or something.
As you can see I dont know jack about cars or anything and my friend is into new stuff so he doesnt know much about the old muscle cars so any help/advice you could give me would be greatly appreciated.
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Hey welcome to the forums i also have a 72 chevelle ss with a 350....... One thing you dont want to forget about these cars is that they are HEAVY! You need some serious torque to get it moving because of the weight issuie. But it could be a million things that are holding you back. I know you dont know much about cars but this is a very good place to learn. Also if you can find out what kind of heads are on that motor? Some aluminum heads that flow pretty well should get it moving more in the direction you want. If your exhaust is brand new then i would probly just leave it alone, but as everyone will tell you up front most of the flowmaster mufflers flow very poorly might want to switch out to something else could pick up another 20-30 hp.......
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From: Florida
Originally Posted by violent_celerity
wow....someone that doesnt know jack about cars getting a 72 chevelle ss....
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From: Gainesville, Florida # of drag strips runs: ?!?!?
A '72 Chevelle Malibu was my first car. Oh, the memories.....
The pedal not going down all the way could be a # of things:
-Is the carpet (or a floormat) bunching up around the pedal making it hard to completely press it down?
-The cable could be binding (this can happen when using a stock length cable on an aftermarket intake with a taller plenum that stretches it).
-Does it have a return spring (or springs) that are stiff and restrict opening?
If these all check out, have someone check for full throttle under the hood when you are in the driver seat. Have the car off, and mat the throttle in one quick motion while a buddy checks under the hood (mat the gas, and have him/her check to see if the arm can go any farther than your initial pressing of it. If so, you can try and fix the reason).
Also, going 60 mph at 2500 (unless you have a bum tach reading, really tall tires or an overdrive transmission), you are more than likely running between a 3.42 and 3.73 gear ratio.
Good luck getting her fixed!
Derek
The pedal not going down all the way could be a # of things:
-Is the carpet (or a floormat) bunching up around the pedal making it hard to completely press it down?
-The cable could be binding (this can happen when using a stock length cable on an aftermarket intake with a taller plenum that stretches it).
-Does it have a return spring (or springs) that are stiff and restrict opening?
If these all check out, have someone check for full throttle under the hood when you are in the driver seat. Have the car off, and mat the throttle in one quick motion while a buddy checks under the hood (mat the gas, and have him/her check to see if the arm can go any farther than your initial pressing of it. If so, you can try and fix the reason).
Also, going 60 mph at 2500 (unless you have a bum tach reading, really tall tires or an overdrive transmission), you are more than likely running between a 3.42 and 3.73 gear ratio.
Good luck getting her fixed!
Derek
First check the carb throttle linkage to make sure your butterflies are opening all the way. With the car off Take the air cleaner off and using your hand actuate the throttle linkage (pull the throttle cable like stepping on the gas does) look straight down into the carb and make sure the butterflies are fully opened e.g. straight up and down
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Launching!
Joined: Feb 2007
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From: Phoenix,AZ
Originally Posted by Strokinit383
Whats that supposed to mean??? The guy comes here for help and guidance and you have to say something like that...come on. If you dont have any useful input then dont post.
BTW: didnt mean to sound like an *******, hes just one hell of a lucky person.
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Teching In
Joined: Nov 2006
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From: TN
I have a 64 Impala with a 350, 10.2 to 1 compression, a performer rpm intake manifold, 1.94/1.60 heads, a holly 750, 4.10 gears and I am riding on 60 series 14 inch tires(torq thrust) and I am at around 3400 to 3600 rpm at 60 mph. Also My car is damn near the same weight as yours if not a little heavier and with my setup I have no complaints at all. I am hitting high 13's at around 103mph with a stock stall and a very very mild cam
Sounds like linkage or the carpet. Both are easy to fix, you just need someone in the car to press the go pedal all the way down, as stated above. Once the pedal is on the floor, try to push the linkage on the carb back further, if it turns more your not getting wide open throttle. Check to see if the pedal can move further down, if not, shorten the linkage at the carb, which should raise the petal to give more travel.
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Teching In
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Wow, I appreciate all the help guys, didnt expect this well of a response.
Ok, i had already check for carpet being holding back the gas petal as well as the full throttle. Metal goes down all the way. Those were my intial thoughts. So im thinking maybe the butterflies are not opening up all the way. Im not sure about the heads though, but im pretty sure they are aluminum, but i dont know the brand.
The 3:73 sounds right though.
The flowmasters put on were supposed to help theyguy said, my dads friend owns The Exhaust Shop here in birmingham.An H-pipe is how he ran it. But then again, I dont know thats why im asking you guys. Are all flowmasters bad?
Violent, no harm no foul dude, i get that alot. The reason im a getting this car is because my dad owns a classic car business, where he buys and sells older musclecars. He had acess to many parts and he wanted me to build the car from the ground up so that I would appreciate it and take care of it. So he bought me a clunker that ive been working on for the past 2 and a half years. We had to fully restore it. He offered to let me swap it for like a '01 or 02 corvette but I really want my car because ive put so much work into.
Ok so, what ive kinda concluded so far, is that I might need to shorten the linkage at the car to open the buterflies in the carb once i check them.
Ok, i had already check for carpet being holding back the gas petal as well as the full throttle. Metal goes down all the way. Those were my intial thoughts. So im thinking maybe the butterflies are not opening up all the way. Im not sure about the heads though, but im pretty sure they are aluminum, but i dont know the brand.
The 3:73 sounds right though.
The flowmasters put on were supposed to help theyguy said, my dads friend owns The Exhaust Shop here in birmingham.An H-pipe is how he ran it. But then again, I dont know thats why im asking you guys. Are all flowmasters bad?
Violent, no harm no foul dude, i get that alot. The reason im a getting this car is because my dad owns a classic car business, where he buys and sells older musclecars. He had acess to many parts and he wanted me to build the car from the ground up so that I would appreciate it and take care of it. So he bought me a clunker that ive been working on for the past 2 and a half years. We had to fully restore it. He offered to let me swap it for like a '01 or 02 corvette but I really want my car because ive put so much work into.
Ok so, what ive kinda concluded so far, is that I might need to shorten the linkage at the car to open the buterflies in the carb once i check them.
Last edited by 1972ChevelleSS; May 10, 2007 at 04:31 PM.
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Originally Posted by 1972ChevelleSS
Wow, I appreciate all the help guys, didnt expect this well of a response.
Ok, i had already check for carpet being holding back the gas petal as well as the full throttle. Metal goes down all the way. Those were my intial thoughts. So im thinking maybe the butterflies are not opening up all the way. Im not sure about the heads though, but im pretty sure they are aluminum, but i dont know the brand.
The 3:73 sounds right though.
The flowmasters put on were supposed to help theyguy said, my dads friend owns The Exhaust Shop here in birmingham.An H-pipe is how he ran it. But then again, I dont know thats why im asking you guys. Are all flowmasters bad?
Violent, no harm no foul dude, i get that alot. The reason im a getting this car is because my dad owns a classic car business, where he buys and sells older musclecars. He had acess to many parts and he wanted me to build the car from the ground up so that I would appreciate it and take care of it. So he bought me a clunker that ive been working on for the past 2 and a half years. We had to fully restore it. He offered to let me swap it for like a '01 or 02 corvette but I really want my car because ive put so much work into.
Ok so, what ive kinda concluded so far, is that I might need to shorten the linkage at the car to open the buterflies in the carb once i check them.
Ok, i had already check for carpet being holding back the gas petal as well as the full throttle. Metal goes down all the way. Those were my intial thoughts. So im thinking maybe the butterflies are not opening up all the way. Im not sure about the heads though, but im pretty sure they are aluminum, but i dont know the brand.
The 3:73 sounds right though.
The flowmasters put on were supposed to help theyguy said, my dads friend owns The Exhaust Shop here in birmingham.An H-pipe is how he ran it. But then again, I dont know thats why im asking you guys. Are all flowmasters bad?
Violent, no harm no foul dude, i get that alot. The reason im a getting this car is because my dad owns a classic car business, where he buys and sells older musclecars. He had acess to many parts and he wanted me to build the car from the ground up so that I would appreciate it and take care of it. So he bought me a clunker that ive been working on for the past 2 and a half years. We had to fully restore it. He offered to let me swap it for like a '01 or 02 corvette but I really want my car because ive put so much work into.
Ok so, what ive kinda concluded so far, is that I might need to shorten the linkage at the car to open the buterflies in the carb once i check them.
Teching In
Joined: Mar 2007
Posts: 32
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From: The boondocks, Missouri
Originally Posted by Villain281H
Also, going 60 mph at 2500 (unless you have a bum tach reading, really tall tires or an overdrive transmission), you are more than likely running between a 3.42 and 3.73 gear ratio.
Flowmasters are crap for any real performance.....I speak first hand on this as I gained some power by replacing the Flowmasters on my car with some Dynomax Ultraflows, which is essentially a straight pipe thru a muffler with alot of packing.
All Flowmasters do make the car sound good, but a good sounding car doesn't mean it's running at it's best.
When you put the engine together did you make sure the cam/heads/carb/timing/stall were in order and would work together? Do you have the right compression ratio for all the parts you used?
Yes if you have too big of a cam and not enough compression it will be a pooch. If the heads are of a poor flowing type it will be a pooch. You need to verify all the parts used in your engines build and then post back.
If your carburetor is a vacuum secondary type the secondary butterflies won't open when you wing it in the drive way. They only open when the engine is under load and actually needs the extra air, such as while moving down the highway. This however does not hold true for a mechanical secondary type carb such as a Holley double pumper.
An excellent chelle board to ask your questions (and get alot of responses) is www.chevelles.com/forums
Launching!
Joined: Feb 2007
Posts: 263
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From: Phoenix,AZ
Originally Posted by 1972ChevelleSS
Wow, I appreciate all the help guys, didnt expect this well of a response.
Ok, i had already check for carpet being holding back the gas petal as well as the full throttle. Metal goes down all the way. Those were my intial thoughts. So im thinking maybe the butterflies are not opening up all the way. Im not sure about the heads though, but im pretty sure they are aluminum, but i dont know the brand.
The 3:73 sounds right though.
The flowmasters put on were supposed to help theyguy said, my dads friend owns The Exhaust Shop here in birmingham.An H-pipe is how he ran it. But then again, I dont know thats why im asking you guys. Are all flowmasters bad?
Violent, no harm no foul dude, i get that alot. The reason im a getting this car is because my dad owns a classic car business, where he buys and sells older musclecars. He had acess to many parts and he wanted me to build the car from the ground up so that I would appreciate it and take care of it. So he bought me a clunker that ive been working on for the past 2 and a half years. We had to fully restore it. He offered to let me swap it for like a '01 or 02 corvette but I really want my car because ive put so much work into.
Ok so, what ive kinda concluded so far, is that I might need to shorten the linkage at the car to open the buterflies in the carb once i check them.
Ok, i had already check for carpet being holding back the gas petal as well as the full throttle. Metal goes down all the way. Those were my intial thoughts. So im thinking maybe the butterflies are not opening up all the way. Im not sure about the heads though, but im pretty sure they are aluminum, but i dont know the brand.
The 3:73 sounds right though.
The flowmasters put on were supposed to help theyguy said, my dads friend owns The Exhaust Shop here in birmingham.An H-pipe is how he ran it. But then again, I dont know thats why im asking you guys. Are all flowmasters bad?
Violent, no harm no foul dude, i get that alot. The reason im a getting this car is because my dad owns a classic car business, where he buys and sells older musclecars. He had acess to many parts and he wanted me to build the car from the ground up so that I would appreciate it and take care of it. So he bought me a clunker that ive been working on for the past 2 and a half years. We had to fully restore it. He offered to let me swap it for like a '01 or 02 corvette but I really want my car because ive put so much work into.
Ok so, what ive kinda concluded so far, is that I might need to shorten the linkage at the car to open the buterflies in the carb once i check them.
Teching In
Joined: Nov 2006
Posts: 46
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From: TN
I'll tell ya something. My impala is a decently quick car for it's size and having a basic sbc setup but in the end for me I would not care if it was fast at all. Some cars are made to cruise and they do it well. I get more looks, questions, compliments, and thumbs up than my buddies Eclipse which has around $20,000 worth of performance **** on it(fully built/stroked evo swap with a BB GT42 making around 420whp on pump gas and 21psi/near 600whp on race gas and 32psi) and his car looks, sounds, and yells "I'm a race car"
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My guess is that the kickdown linkage isn't installed properly. Does this have a TH350? More than likely it does. The linkage has to be properly adjusted where it attaches to the bellcrank (lever) on the carb. You have a Holley so unless you have the correct pieces (a speed shop should have the proper pieces for the carb) it probably isn't hooked up. Also, depending on what intake manifold you have you may need a different throttle kickdown bracket. This is what holds the kickdown cable off of the manifold and properly aligns it with the bellcrank on the carb. You'll also need the proper pieces to attach it to the carb.
If you have a TH400 then it's a different story. This tranny utlizies a switch which attaches to a bracket that is mounted to the left rear carb mounting stud. The wire plugs into a socket on the right side of the tranny.
BTW: No 72 Chevelle was sold as an SS with a 350 engine. All of the SS's were big block cars. On the other hand in 1972 Cheverolet did make a "Heavy Chevy" which had everything a big block car had (tach, gauges, buckets, and heavy duty running gear like a 12-bolt etc) but it used a 4-bolt main 350 with a 4bbl carb. This was to get around the insurance premiums that were being charged on the higher horse power cars at the time. This may be what you have. Additionally, the "Cowl Induction" hood was functional only on the 70 model but could be fitted to a 71 or 72 and made functional (the opening is vacuum operated). 71 and 72 SS Chevelles had a non-functioning hood.
If you have a TH400 then it's a different story. This tranny utlizies a switch which attaches to a bracket that is mounted to the left rear carb mounting stud. The wire plugs into a socket on the right side of the tranny.
BTW: No 72 Chevelle was sold as an SS with a 350 engine. All of the SS's were big block cars. On the other hand in 1972 Cheverolet did make a "Heavy Chevy" which had everything a big block car had (tach, gauges, buckets, and heavy duty running gear like a 12-bolt etc) but it used a 4-bolt main 350 with a 4bbl carb. This was to get around the insurance premiums that were being charged on the higher horse power cars at the time. This may be what you have. Additionally, the "Cowl Induction" hood was functional only on the 70 model but could be fitted to a 71 or 72 and made functional (the opening is vacuum operated). 71 and 72 SS Chevelles had a non-functioning hood.
