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1979 corvette power trouble.

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Old 01-22-2015, 11:09 PM
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FlippinCorvette
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Default 1979 corvette power trouble.

Lately my vetted had a problem.
I only get about 1/3 to 1/2 my power most if the time. Doesn't matter how want it is or cold. Sometimes I get all my power.
Usually I get it if I drive it a very long amount of time and floor it a while.
When it does the lack of power It also gets alot quieter. Please help
Old 01-22-2015, 11:17 PM
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The13Bats
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Hum...could a cylinder be dying? could be fire could be fuel....

When my vw trike would lose one or two jugs thats 1/4 or 1/2 the power and man do you feel it, on the trike a plug wire fell out of the dizzy, perhaps you are loosing fire in a wire...
Old 01-23-2015, 05:36 AM
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tonak
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Stuck choke?
Old 01-23-2015, 07:24 AM
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7T1vette
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Could be your floor mat is getting under the accel pedal and the throttle carble/linkage is not fully opening the carb. You need to have someone in the car depressing the accel pedal [fully] while you look down into the secondary venturi to see if the throttle plates are vertical (or not). Engine OFF, of course.
Old 01-23-2015, 07:32 AM
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tokim
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Originally Posted by 7T1vette
Could be your floor mat is getting under the accel pedal and the throttle carble/linkage is not fully opening the carb. You need to have someone in the car depressing the accel pedal [fully] while you look down into the secondary venturi to see if the throttle plates are vertical (or not). Engine OFF, of course.
My first thought also.
Old 01-23-2015, 07:46 AM
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FlippinCorvette
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Thank you everyone ill see if these leads find it I really appreciate the help!
Old 01-23-2015, 07:51 AM
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FlippinCorvette
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I forgot a super important detail!!!
I can put in neutral and it will rev normally, the sound isn't quiet like it is in gear when it is short on power. No matter what when I put it in neutral it has the sound like it has all it's power
Old 01-23-2015, 03:46 PM
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Any new ideas??
Old 01-23-2015, 04:09 PM
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The13Bats
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Well, I doubt that it's something under the gas pedal,

So it revs fine in netural, no load,

you say it losses sound, so I really believe you are loosing cylinders but not all of them, so again it's fire or fuel...
a choke issue could do it,
Bad wires, rotor, cap plugs, coil

So you say when you get on it a while it clears the problem?
have you taken a look at your spark plugs see what they have to say about it....
Old 01-24-2015, 08:40 AM
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Tooonz
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I agree with Bats more basic information is needed.
Old 01-24-2015, 09:16 AM
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LS4 PILOT
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First guess is plugs or wires or both. Wires are old grounding intermittent , plugs fouling . Then I d investigate the ignition . Good steady current flow .
Old 01-24-2015, 12:35 PM
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Exhaust plugging up?
Old 01-24-2015, 10:51 PM
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7T1vette
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I doubt that Bats is right. (Back at ya, dude....)

We are all just offering suggestions that might cause your problem. NONE OF US knows what the real cause might be. And, the carb not opening fully is a very common problem (whether Bats knows it or not).
Old 01-27-2015, 02:54 PM
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The13Bats
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Originally Posted by 7T1vette
I doubt that Bats is right. (Back at ya, dude....)

We are all just offering suggestions that might cause your problem. NONE OF US knows what the real cause might be. And, the carb not opening fully is a very common problem (whether Bats knows it or not).

I actually wondered if you were joking about carpet bunged up under the pedal as far as this thread was concerned, because this problem isnt there all the time, IE not there in neutral.
I do know carpet or things can get under the pedal, I assumed ( my bad ) most people are in tune enough with their vettes that they would feel a difference in their foot as they pressed the pedal, it would "feel" different if something was under the pedal, well, it would to me.

While I will not agree it's commonly caused by bunged carpet you are very correct and affirming it many shops that set up overdrive state sometime like 60-70% of carbureted cars have a carb that doesn't fully open due to cable/linkage, I also read on this forum the pedal can bend where the cable attaches and cause the carb not to open all the way.

But again, after reading what the op said I still personally feel that his issue is related to a fire and or fuel problem not carb opening all the way ( not that he doesnt have that issue in addition to this ) because he doesn't have the problem in netural for example.

Feel free to doubt I am right I could be dead wrong...my ego can take it,
I was just giving my opinion trying to help the fellow, like you say none of us know for sure what is wrong.
I wasn't dissing you in any way sorry you got all upset, not my intention, ....
Old 01-27-2015, 03:18 PM
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FlippinCorvette
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Gonna leave it with a buddy of mine over the weekend who restores and mods all of his own vettes (he has many) I have faith he will figure it out
Old 01-27-2015, 03:38 PM
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Peterbuilt
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Default My guess!

Could the spring for the secondary air valve spring be adjusted to tight?

Or as Tonak says, the choke not working correctly and preventing the choke linkage 'lockout' from disengaging.
Old 01-27-2015, 09:00 PM
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Originally Posted by Peterbuilt
Could the spring for the secondary air valve spring be adjusted to tight?

Or as Tonak says, the choke not working correctly and preventing the choke linkage 'lockout' from disengaging.
Something that is not happening when in netural
On my solex vw stuff I have seen some choke issues come and go...


Originally Posted by FlippinCorvette
Gonna leave it with a buddy of mine over the weekend who restores and mods all of his own vettes (he has many) I have faith he will figure it out
I bet he does get it going right for you, also from your other post ask him about hopping it up a little...

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Old 01-27-2015, 10:42 PM
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FlippinCorvette
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Originally Posted by The13Bats
Something that is not happening when in netural
On my solex vw stuff I have seen some choke issues come and go...




I bet he does get it going right for you, also from your other post ask him about hopping it up a little...
Ill ask his opinion about what I should do!
Old 01-28-2015, 04:14 PM
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The13Bats
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Originally Posted by FlippinCorvette
Ill ask his opinion about what I should do!
I had two 81's put over 100K on one as a daily driver, I admit the stock engine wasnt any kind of beast, I do understand why you desire more kick out of your 79, but take your time, be honest with yourself what you really want and how you will really use the car, more isnt always better...my 66 for example, I dropped in a 327 that was likely 300-350 hp it was a little beast to live with as a daily driver, so like I say take your time planning out what you really want, it will save $$$ and headaches.
Old 01-29-2015, 04:22 PM
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Originally Posted by The13Bats
I had two 81's put over 100K on one as a daily driver, I admit the stock engine wasnt any kind of beast, I do understand why you desire more kick out of your 79, but take your time, be honest with yourself what you really want and how you will really use the car, more isnt always better...my 66 for example, I dropped in a 327 that was likely 300-350 hp it was a little beast to live with as a daily driver, so like I say take your time planning out what you really want, it will save $$$ and headaches.
thanks man!


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