Thanks for the POWAAAHHH!
10-18-2016, 01:41 PM
#1
Dementer sole survivor
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Thanks for the POWAAAHHH!
So ever since I got my 68 corvette a year ago I thought it was a dog. Don't get me wrong, it had some get up and go above 2500 rpm but really couldnt spin the tires easily. I thought it might be a bit under powered since it had a 72 motor and 235 60s on it. If you blipped the throttle at any speed, it would jump, but it just didn't seem like it was an LT-1 motor. Not that I remembered any way. I remembered a wild animal from my younger years
I have a 72 Lt-1 with a performer air gap, hei, headers, 2 inch pipes to side pipes, edelbrock 600 1406 model, muncie m21 with 3.70 gears. It only has 9:1 compression from 76cc heads. I bought some 64cc heads that are sitting on the shelf until spring, it will give me about 10.25:1. I've also been looking at 750 carbs but read it will only really give me a bit more top end, which isnt the quest. But It should roast the tires pretty easily as is, but won't. It will put you into the seat once your moving, down shifting and going to floor will make you smile but that nagging of nothing off the line is lame.
I thought it was a week carb, bad timing, miss adjusted valves. It was all that. I have it timed to be 36* all in at 2500 rpm, mechanical solid lifters properly adjusted, and I finally put in the 1405 jets and rods, which really made a difference at low rpm. I had the 1406 rods and jets a couple stages up in the band but that really didnt help. I was getting about 16 mpg no matter how I drove. The vacuum is steady at 15hg. Still no big smile off the line. No squeal, just a bit of a grab and launch, but it should have that little bit more. So I kept looking for the beast.
Now I've been reading alot from you guys, and adjusting and manipulating and the other day I found a thread and somebody was saying they thought their vette should have more. So they checked the throttle cable and it wasn't pulling to WOT. I thought to myself " Self, you shoukd make sure you're getting full throttle." I knew I wasnt because I was hitting the floor with the pedal and thought it wasnt pulling far enough cable. I just never really followed up until this morning
So I thought I would try to move my cable attachment point but the set screws interferred. While I was there I pulled the throttle to where my current full throttle positon was and it kind of picked up a bit of pressure, and stpoped. That was my current full throttle. So I pulled the arm further and it continued further. The pressure was the secondaries openning. WTF
All summer long I have been hot roddng around having a hell of a time, smiling big, thinking life was good, and I wasnt even opening the secondaries. Holy crap I had to fix this fast. So I pulled the gas pedal out and put it in the vise. I gave it a gentle nudge with a 15" wrench to give it a bit more room above the floor. While I was there I went up 2 levels in the power range with the rods and put it all together.
So I survived the test drive but I think I broke my face from the biggest grin I ever had.
Now I have to be carefull off the line because she now has the power of a Grizzly. Wow. Just blipping the throttle to the floor after a rolling start will spin the tires. I went down a deserted road to light them up and from popping the clutch and going to floor the rearend came loose, so I backed off the throttle and she straightened out so I went back in again, spinning away again. Now thats what I remembered from my uncles Vette when I was too small to really see over the door. On my way home I was leaving a stop sign under normal acceleration as a car was coming so I got on it just a little and she broke loose for a short distance.
Now I'm power hungry, what a great feeling. Life is good
I have a 72 Lt-1 with a performer air gap, hei, headers, 2 inch pipes to side pipes, edelbrock 600 1406 model, muncie m21 with 3.70 gears. It only has 9:1 compression from 76cc heads. I bought some 64cc heads that are sitting on the shelf until spring, it will give me about 10.25:1. I've also been looking at 750 carbs but read it will only really give me a bit more top end, which isnt the quest. But It should roast the tires pretty easily as is, but won't. It will put you into the seat once your moving, down shifting and going to floor will make you smile but that nagging of nothing off the line is lame.
I thought it was a week carb, bad timing, miss adjusted valves. It was all that. I have it timed to be 36* all in at 2500 rpm, mechanical solid lifters properly adjusted, and I finally put in the 1405 jets and rods, which really made a difference at low rpm. I had the 1406 rods and jets a couple stages up in the band but that really didnt help. I was getting about 16 mpg no matter how I drove. The vacuum is steady at 15hg. Still no big smile off the line. No squeal, just a bit of a grab and launch, but it should have that little bit more. So I kept looking for the beast.
Now I've been reading alot from you guys, and adjusting and manipulating and the other day I found a thread and somebody was saying they thought their vette should have more. So they checked the throttle cable and it wasn't pulling to WOT. I thought to myself " Self, you shoukd make sure you're getting full throttle." I knew I wasnt because I was hitting the floor with the pedal and thought it wasnt pulling far enough cable. I just never really followed up until this morning
So I thought I would try to move my cable attachment point but the set screws interferred. While I was there I pulled the throttle to where my current full throttle positon was and it kind of picked up a bit of pressure, and stpoped. That was my current full throttle. So I pulled the arm further and it continued further. The pressure was the secondaries openning. WTF
All summer long I have been hot roddng around having a hell of a time, smiling big, thinking life was good, and I wasnt even opening the secondaries. Holy crap I had to fix this fast. So I pulled the gas pedal out and put it in the vise. I gave it a gentle nudge with a 15" wrench to give it a bit more room above the floor. While I was there I went up 2 levels in the power range with the rods and put it all together.
So I survived the test drive but I think I broke my face from the biggest grin I ever had.
Now I have to be carefull off the line because she now has the power of a Grizzly. Wow. Just blipping the throttle to the floor after a rolling start will spin the tires. I went down a deserted road to light them up and from popping the clutch and going to floor the rearend came loose, so I backed off the throttle and she straightened out so I went back in again, spinning away again. Now thats what I remembered from my uncles Vette when I was too small to really see over the door. On my way home I was leaving a stop sign under normal acceleration as a car was coming so I got on it just a little and she broke loose for a short distance.
Now I'm power hungry, what a great feeling. Life is good
Last edited by Rescue Rogers; 10-18-2016 at 01:47 PM.
10-18-2016, 02:08 PM
#2
Melting Slicks
Member Since: Aug 2004
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Probably a dumb question, but i do not understand some of your terminology. Are you saying the back 2 barrels of the carb were not opening?
I ask because I am having that issue with my 72 base engine. It has the Rochester Quad carb.
I ask because I am having that issue with my 72 base engine. It has the Rochester Quad carb.
So ever since I got my 68 corvette a year ago I thought it was a dog. Don't get me wrong, it had some get up and go above 2500 rpm but really couldnt spin the tires easily. I thought it might be a bit under powered since it had a 72 motor and 235 60s on it. If you blipped the throttle at any speed, it would jump, but it just didn't seem like it was an LT-1 motor. Not that I remembered any way. I remembered a wild animal from my younger years
I have a 72 Lt-1 with a performer air gap, hei, headers, 2 inch pipes to side pipes, edelbrock 600 1406 model, muncie m21 with 3.70 gears. It only has 9:1 compression from 76cc heads. I bought some 64cc heads that are sitting on the shelf until spring, it will give me about 10.25:1. I've also been looking at 750 carbs but read it will only really give me a bit more top end, which isnt the quest. But It should roast the tires pretty easily as is, but won't. It will put you into the seat once your moving, down shifting and going to floor will make you smile but that nagging of nothing off the line is lame.
I thought it was a week carb, bad timing, miss adjusted valves. It was all that. I have it timed to be 36* all in at 2500 rpm, mechanical solid lifters properly adjusted, and I finally put in the 1405 jets and rods, which really made a difference at low rpm. I had the 1406 rods and jets a couple stages up in the band but that really didnt help. I was getting about 16 mpg no matter how I drove. The vacuum is steady at 15hg. Still no big smile off the line. No squeal, just a bit of a grab and launch, but it should have that little bit more. So I kept looking for the beast.
Now I've been reading alot from you guys, and adjusting and manipulating and the other day I found a thread and somebody was saying they thought their vette should have more. So they checked the throttle cable and it wasn't pulling to WOT. I thought to myself " Self, you shoukd make sure you're getting full throttle." I knew I wasnt because I was hitting the floor with the pedal and thought it wasnt pulling far enough cable. I just never really followed up until this morning
So I thought I would try to move my cable attachment point but the set screws interferred. While I was there I pulled the throttle to where my current full throttle positon was and it kind of picked up a bit of pressure, and stpoped. That was my current full throttle. So I pulled the arm further and it continued further. The pressure was the secondaries openning. WTF
All summer long I have been hot roddng around having a hell of a time, smiling big, thinking life was good, and I wasnt even opening the secondaries. Holy crap I had to fix this fast. So I pulled the gas pedal out and put it in the vise. I gave it a gentle nudge with a 15" wrench to give it a bit more room above the floor. While I was there I went up 2 levels in the power range with the rods and put it all together.
So I survived the test drive but I think I broke my face from the biggest grin I ever had.
Now I have to be carefull off the line because she now has the power of a Grizzly. Wow. Just blipping the throttle to the floor after a rolling start will spin the tires. I went down a deserted road to light them up and from popping the clutch and going to floor the rearend came loose, so I backed off the throttle and she straightened out so I went back in again, spinning away again. Now thats what I remembered from my uncles Vette when I was too small to really see over the door. On my way home I was leaving a stop sign under normal acceleration as a car was coming so I got on it just a little and she broke loose for a short distance.
Now I'm power hungry, what a great feeling. Life is good
I have a 72 Lt-1 with a performer air gap, hei, headers, 2 inch pipes to side pipes, edelbrock 600 1406 model, muncie m21 with 3.70 gears. It only has 9:1 compression from 76cc heads. I bought some 64cc heads that are sitting on the shelf until spring, it will give me about 10.25:1. I've also been looking at 750 carbs but read it will only really give me a bit more top end, which isnt the quest. But It should roast the tires pretty easily as is, but won't. It will put you into the seat once your moving, down shifting and going to floor will make you smile but that nagging of nothing off the line is lame.
I thought it was a week carb, bad timing, miss adjusted valves. It was all that. I have it timed to be 36* all in at 2500 rpm, mechanical solid lifters properly adjusted, and I finally put in the 1405 jets and rods, which really made a difference at low rpm. I had the 1406 rods and jets a couple stages up in the band but that really didnt help. I was getting about 16 mpg no matter how I drove. The vacuum is steady at 15hg. Still no big smile off the line. No squeal, just a bit of a grab and launch, but it should have that little bit more. So I kept looking for the beast.
Now I've been reading alot from you guys, and adjusting and manipulating and the other day I found a thread and somebody was saying they thought their vette should have more. So they checked the throttle cable and it wasn't pulling to WOT. I thought to myself " Self, you shoukd make sure you're getting full throttle." I knew I wasnt because I was hitting the floor with the pedal and thought it wasnt pulling far enough cable. I just never really followed up until this morning
So I thought I would try to move my cable attachment point but the set screws interferred. While I was there I pulled the throttle to where my current full throttle positon was and it kind of picked up a bit of pressure, and stpoped. That was my current full throttle. So I pulled the arm further and it continued further. The pressure was the secondaries openning. WTF
All summer long I have been hot roddng around having a hell of a time, smiling big, thinking life was good, and I wasnt even opening the secondaries. Holy crap I had to fix this fast. So I pulled the gas pedal out and put it in the vise. I gave it a gentle nudge with a 15" wrench to give it a bit more room above the floor. While I was there I went up 2 levels in the power range with the rods and put it all together.
So I survived the test drive but I think I broke my face from the biggest grin I ever had.
Now I have to be carefull off the line because she now has the power of a Grizzly. Wow. Just blipping the throttle to the floor after a rolling start will spin the tires. I went down a deserted road to light them up and from popping the clutch and going to floor the rearend came loose, so I backed off the throttle and she straightened out so I went back in again, spinning away again. Now thats what I remembered from my uncles Vette when I was too small to really see over the door. On my way home I was leaving a stop sign under normal acceleration as a car was coming so I got on it just a little and she broke loose for a short distance.
Now I'm power hungry, what a great feeling. Life is good
Last edited by crawfish333; 10-18-2016 at 02:20 PM.
10-18-2016, 02:10 PM
#3
Melting Slicks
Same story with me too!
Same story with my 68 454 too. Played with everything, the guy I bought it from said it was kinda of slow too. Finally looked down the holes of the q jet while the wife pushed the accelerator pedal all of the way down and dang the mechanical secondaries were not even cracked open. 
So played with the throttle cable, played with bracket and finally did the same, pulled the accelerator pedal arm out and bent it just a tweak and all is good now. Big difference when the secondaries are working!
Next time, I think I will check for this first
So played with the throttle cable, played with bracket and finally did the same, pulled the accelerator pedal arm out and bent it just a tweak and all is good now. Big difference when the secondaries are working!
Next time, I think I will check for this first
10-18-2016, 02:15 PM
#4
Drifting
Same story with my 68 454 too. Played with everything, the guy I bought it from said it was kinda of slow too. Finally looked down the holes of the q jet while the wife pushed the accelerator pedal all of the way down and dang the mechanical secondaries were not even cracked open.
So played with the throttle cable, played with bracket and finally did the same, pulled the accelerator pedal arm out and bent it just a tweak and all is good now. Big difference when the secondaries are working!
Next time, I think I will check for this first
So played with the throttle cable, played with bracket and finally did the same, pulled the accelerator pedal arm out and bent it just a tweak and all is good now. Big difference when the secondaries are working!
Next time, I think I will check for this first
Wes
10-18-2016, 02:31 PM
#5
https://www.corvetteforum.com/forums...r-problem.html
I offered this very solution there, but nobody seemed interested.
Last edited by Faster Rat; 10-18-2016 at 02:34 PM.
The following 2 users liked this post by Faster Rat:
doorgunner (10-18-2016),
Rescue Rogers (10-18-2016)
10-18-2016, 03:57 PM
#6
Dementer sole survivor
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If it was, thanks for the inspiration!!!
10-18-2016, 04:02 PM
#7
Dementer sole survivor
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Some carburetor s have vacuum secondaries that open as the carb draws more air/ creates more vacuum. Not sure how the vacuum plumbing works on those models.
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crawfish333 (10-18-2016)
10-18-2016, 04:03 PM
#8
Dementer sole survivor
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Come on weekend!!!!!. I need a drive!!!!!.........! BAAAAAAADD!!!!
10-18-2016, 07:55 PM
#10
Dementer sole survivor
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Yaaaaaa. About thaaatt, yaaaa. 
Theyre new last February, I think I can rotate them in the spring and get another summer out of them, buuuuut that will get me closer to those redlines I always wanted
Theyre new last February, I think I can rotate them in the spring and get another summer out of them, buuuuut that will get me closer to those redlines I always wanted
10-18-2016, 08:27 PM
#11
Nam Labrat
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I have all the power I need as is......without getting me-self in twouble!
10-18-2016, 09:41 PM
#12
Dementer sole survivor
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Awwww DG ya know ya wanna do it. Come on. I'll do it for ya. The first one is free. It won't hurt, we'll go slow. Naaa, its not addicting, they said so on the internet!!!!!
Last edited by Rescue Rogers; 10-18-2016 at 09:44 PM.
10-18-2016, 11:09 PM
#13
Melting Slicks
Well, .....
Well, just because you can make your secondaries open does not mean you have to choose to do so
I suppose you really could keep your foot out of it if you wanted to.
I suppose you really could keep your foot out of it if you wanted to.
10-19-2016, 01:08 AM
#14
Nam Labrat
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Last edited by doorgunner; 10-19-2016 at 01:08 AM.
10-19-2016, 07:43 AM
#15
Dementer sole survivor
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What could possibly go wrong??!!