Few probs with a 1971
Thread Starter
Instructor
Joined: Jul 2006
Posts: 150
Likes: 0
From: Cherry Point NC
Few probs with a 1971
OK, before I begin this project:
http://forums.corvetteforum.com/show....php?t=1571994
I need to fix a couple drivability probs with the stone stock 1971 corvette.
1) It doesn't have power brakes. Is there some kind of conversion kit so I can install power brakes?
2) The power steering is a little sloppy. There is about 2 inches of play in the steering wheel before the car starts to turn. Is that normal, or can I do something to tighten up the steering response?
3) I tried to advance the timing a few degrees today, but I had some trouble. The stock crank pulley only goes up to 12* advance on it's timing scale.
At idle, the timing was at exactly zero. As I advanced the throttle, the timing increased, until it was off the scale. I advanced the distributor to 3* at idle, and as RPM increases the spark still jumps off the scale. How much total timing have I added? Do I need an aftermarket damper to tell?
I took all the play out of the throttle cable, and the carb opens to more than 50% when I floor the pedal. It's alot more powerful now.
I bled the brakes, and it stops alot better than it did, but it still feels spongy and crappy. There are no leaks in the system. I guess I'll have to bleed them some more. This is my first non power brake car. Are the brakes supposed to feel spongy?
http://forums.corvetteforum.com/show....php?t=1571994
I need to fix a couple drivability probs with the stone stock 1971 corvette.
1) It doesn't have power brakes. Is there some kind of conversion kit so I can install power brakes?
2) The power steering is a little sloppy. There is about 2 inches of play in the steering wheel before the car starts to turn. Is that normal, or can I do something to tighten up the steering response?
3) I tried to advance the timing a few degrees today, but I had some trouble. The stock crank pulley only goes up to 12* advance on it's timing scale.
At idle, the timing was at exactly zero. As I advanced the throttle, the timing increased, until it was off the scale. I advanced the distributor to 3* at idle, and as RPM increases the spark still jumps off the scale. How much total timing have I added? Do I need an aftermarket damper to tell?
I took all the play out of the throttle cable, and the carb opens to more than 50% when I floor the pedal. It's alot more powerful now.
I bled the brakes, and it stops alot better than it did, but it still feels spongy and crappy. There are no leaks in the system. I guess I'll have to bleed them some more. This is my first non power brake car. Are the brakes supposed to feel spongy?
Melting Slicks
Joined: Dec 2005
Posts: 2,441
Likes: 0
OK here go's:
1) Yes there are conversions available, probably VB products.
2) 2" is way too much, check your tie-rods ends, idler link, and relay rods, ball joints for wear, you might as well evaluate the whole front end. Also, the steering box has an adjustment on top.
3) The timing spec should be around 8 degrees, no need to go that far. Also, you need to have the spark vacuum advance disconnected to set correctly.
The brakes could need attention, they're notorious for drawing air past the seals if the caliper run-out is out of spec, very tight tolerances.
Finding the throttle plates opening only 50%, priceless.
1) Yes there are conversions available, probably VB products.
2) 2" is way too much, check your tie-rods ends, idler link, and relay rods, ball joints for wear, you might as well evaluate the whole front end. Also, the steering box has an adjustment on top.
3) The timing spec should be around 8 degrees, no need to go that far. Also, you need to have the spark vacuum advance disconnected to set correctly.
The brakes could need attention, they're notorious for drawing air past the seals if the caliper run-out is out of spec, very tight tolerances.
Finding the throttle plates opening only 50%, priceless.
Last edited by shafrs3; Dec 13, 2006 at 10:53 PM.
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
You can buy a master cylinder/vacuum booster assembly from Advance Auto for ~$90.00. You will probably have to bend the brake lines or replace them to fit the MC. Figure on spending an unpleasant afternoon installing the booster nuts under the dash. All you have to do besides install the booster/MC is connect a vacuum line from the intake manifold to the booster.
Check out Lar's paper on ignition timing. You should be able to get the timing set correctly with the original damper.
Bleeding the brakes can be tricky. There has been a lot of debate on the forum regarding the "correct" sequence. I used what is supposed to be the factory sequence and it worked well for me. The sequence is different than most conventional bleeding sequences. From memory it is:
LR outer
LR inner
RR outer
RR inner
LF
RF
To make matters worse, if the disk runout is excessive the calipers will suck air in (without leaking fluid) and become spongy again.
Rick B.
Check out Lar's paper on ignition timing. You should be able to get the timing set correctly with the original damper.
Bleeding the brakes can be tricky. There has been a lot of debate on the forum regarding the "correct" sequence. I used what is supposed to be the factory sequence and it worked well for me. The sequence is different than most conventional bleeding sequences. From memory it is:
LR outer
LR inner
RR outer
RR inner
LF
RF
To make matters worse, if the disk runout is excessive the calipers will suck air in (without leaking fluid) and become spongy again.
Rick B.
Advanced
Joined: Feb 2004
Posts: 88
Likes: 0
From: MAYWOOD MO
Manual brakes on a 71 stop the car very well when in good condition. I would work on making sure the stock system is function properly. Just my 2 cents.
The adjustment on the steering box is easy and can make a world of difference. If you search I know there's a good write up on setting it up properly.
If you buy a dial-back timing light as recommended in Lars' timing paper, you can read any advance you want. You simply turn the dial on the light until it shows 0 on your damper.
The adjustment on the steering box is easy and can make a world of difference. If you search I know there's a good write up on setting it up properly.
If you buy a dial-back timing light as recommended in Lars' timing paper, you can read any advance you want. You simply turn the dial on the light until it shows 0 on your damper.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
OK, before I begin this project:
http://forums.corvetteforum.com/show....php?t=1571994
I need to fix a couple drivability probs with the stone stock 1971 corvette.
http://forums.corvetteforum.com/show....php?t=1571994
I need to fix a couple drivability probs with the stone stock 1971 corvette.
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
My manual brakes will easily lock up all 4 wheels. The pedal is very firm - you might check for leaks or re-bleed them. They do take more effort though, but I like the feel...
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Tech Contributor
Joined: Aug 1999
Posts: 15,187
Likes: 4,008
From: Connecticut, USA
Check the front suspension BEFORE going near the steering box. Then with the car jacked up in front, have someone turn the steering wheel while you look at the rag joint, box input and the pitman arm( output).
When the box is on center,in the middle of travel, there should be no lost motion in the box. Turning the wheel should transfer through the box to the pitman arm. If you find lost motion then let me know and I'll give you some tips on adjusting the box. Look at the threads in the lash screw in the cover,can you see any threads above the jam nut?
Manual brake do work very good if the system is setup correctly. You have to understand the vette brake system to properly set it up. This is not intended as an insult but if this is your 1st vette the brakes can drive you crazy. You have to have under .002 runout in the rotors and .002 endplay in the bearings to have a superior brake system- power or manual. Since this is a newly purchased car it is possible the previous owner knew this and decided to sell vs repair correctly- not uncommon to happen.
Lars is Thors cousin, Zeus's nephew! He carries a mini Hammer of Thor and may be able to fly! He's been seen around the world,beer in one hand, Hammer in the other, corvette in front of him!
Gary
When the box is on center,in the middle of travel, there should be no lost motion in the box. Turning the wheel should transfer through the box to the pitman arm. If you find lost motion then let me know and I'll give you some tips on adjusting the box. Look at the threads in the lash screw in the cover,can you see any threads above the jam nut?
Manual brake do work very good if the system is setup correctly. You have to understand the vette brake system to properly set it up. This is not intended as an insult but if this is your 1st vette the brakes can drive you crazy. You have to have under .002 runout in the rotors and .002 endplay in the bearings to have a superior brake system- power or manual. Since this is a newly purchased car it is possible the previous owner knew this and decided to sell vs repair correctly- not uncommon to happen.
Lars is Thors cousin, Zeus's nephew! He carries a mini Hammer of Thor and may be able to fly! He's been seen around the world,beer in one hand, Hammer in the other, corvette in front of him!
Gary
Drifting
Joined: May 2006
Posts: 1,425
Likes: 0
From: Seattle Wash.
Here is the link to corvettefaq.com main page. This is where you will find a ton of information.
http://wiki.corvettefaq.com/index.php?title=Main_Page
This is the direct link to the Lars tuning info within the corvettefaq website.
http://wiki.corvettefaq.com/index.php?title=Tuning
You will want to scroll down to the 2nd section where it lists:
How to set timing
Quadrajet tuning paper
Those 2 headings will take you to PDF files that you can download or print. Very valuable information.
Take care and good luck!
