1973 Corvette lacking power
Thread Starter
Intermediate
Joined: Dec 2012
Posts: 34
Likes: 2
1973 Corvette lacking power
Hello everyone. I haven't been able to make any significant progress on my '73 in 9 months; due to me being at school. But I have a rebuilt TH400, new pump, new tranny lines, new shift control cable. After taking it out for a drive, the car seemed to lack power. I'd get to about 20 mph and if I tried to push on the gas hard, the car wouldn't go anywhere. It came to me that the gasoline was most likely bad. So as of 05/17/14 I drained all the bad gas in the tank, but not all that was in the fuel lines and filter, as well as a needed engine oil change.
Put new 91 octane gas and going to put a fuel system cleaner in on sunday. Been adjusting the modulator and thats about it. Frustrating to constantly jack the car up and not feel any results. Can anyone give me some pointers, or anyone have a problem similar as this?
Put new 91 octane gas and going to put a fuel system cleaner in on sunday. Been adjusting the modulator and thats about it. Frustrating to constantly jack the car up and not feel any results. Can anyone give me some pointers, or anyone have a problem similar as this?
Instructor
Joined: Oct 2013
Posts: 105
Likes: 1
From: Ventura
Hello everyone. I haven't been able to make any significant progress on my '73 in 9 months; due to me being at school. But I have a rebuilt TH400, new pump, new tranny lines, new shift control cable. After taking it out for a drive, the car seemed to lack power. I'd get to about 20 mph and if I tried to push on the gas hard, the car wouldn't go anywhere. It came to me that the gasoline was most likely bad. So as of 05/17/14 I drained all the bad gas in the tank, but not all that was in the fuel lines and filter, as well as a needed engine oil change.
Put new 91 octane gas and going to put a fuel system cleaner in on sunday. Been adjusting the modulator and thats about it. Frustrating to constantly jack the car up and not feel any results. Can anyone give me some pointers, or anyone have a problem similar as this?
Put new 91 octane gas and going to put a fuel system cleaner in on sunday. Been adjusting the modulator and thats about it. Frustrating to constantly jack the car up and not feel any results. Can anyone give me some pointers, or anyone have a problem similar as this?
Thread Starter
Intermediate
Joined: Dec 2012
Posts: 34
Likes: 2
TH400 was rebuilt by a shop. Rebuilt to original specs, only modification was a deeper pan, and the transmission guy applied the correct longer pick-up tube. I don't believe the throttle cable has changed much since when I left it, but won't hurt to check. When I shift into second gear, the car has a little bit more pick up. However, I did notice something peculiar when I shifted into second. There was a hissing noise; I believe it was the vacuum because I adjusted it before going on my drive. But when I put back into third, the hiss stopped and the lack of get up comes back. All factors are being considered.
Safety Car
Joined: Jan 2009
Posts: 4,000
Likes: 299
From: New York
What do you mean no power ? Is it revving at all in first gear if you put it in manually and leave it there ? Is it hesitating ? If you floor it does it rev and go or does it not rev ?
In park can you race the motor ? How is it in reverse can you hit it and spin tires or feel it pull hard ?
In park can you race the motor ? How is it in reverse can you hit it and spin tires or feel it pull hard ?
Thread Starter
Intermediate
Joined: Dec 2012
Posts: 34
Likes: 2
What do you mean no power ? Is it revving at all in first gear if you put it in manually and leave it there ? Is it hesitating ? If you floor it does it rev and go or does it not rev ?
In park can you race the motor ? How is it in reverse can you hit it and spin tires or feel it pull hard ?
In park can you race the motor ? How is it in reverse can you hit it and spin tires or feel it pull hard ?
Safety Car
Joined: Jan 2009
Posts: 4,000
Likes: 299
From: New York
Engine is fine. When i have it in park I can rev it no problem and it runs healthy. The shifts are nice and smooth, no sign of major internal problem. What I mean by not having any power, is when I try to floor or it even a little bit, it doesn't rev and go, just seems stuck.
I also would check the linkage connection it is possible your not in gear completely or applying 2 gears at the same time because the detente is not moving the valve fully.
And lastly on an out side chance the trans filter could have fallen off or could be plugged the th400 filters use to cause issues.
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Thread Starter
Intermediate
Joined: Dec 2012
Posts: 34
Likes: 2
It sounds like a plugged exhaust which will do exactly what you are describing.
I also would check the linkage connection it is possible your not in gear completely or applying 2 gears at the same time because the detente is not moving the valve fully.
And lastly on an out side chance the trans filter could have fallen off or could be plugged the th400 filters use to cause issues.
I also would check the linkage connection it is possible your not in gear completely or applying 2 gears at the same time because the detente is not moving the valve fully.
And lastly on an out side chance the trans filter could have fallen off or could be plugged the th400 filters use to cause issues.
Exhaust isn't backed up because they're currently aren't any pipes, open headers.
That is the last thing I am going to check. Taking the pan off and checking if the pick-up tube hasn't slipped out.