c3 guy needs c4 help
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Abby Normal
Joined: Dec 2001
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c3 guy needs c4 help
so the brother in law of a friend brings me his '91 L-89/auto and wants me to do a brake job for him. no problem, i can do brakes but not owning a c4 there are several questions i have. 1) the front brakes are wearing unevenly, is this due to the caliper not sliding as it should or something else? 2) from your personal experience, what is the best way to bleed the brakes on ABS system? same as i bleed mine on my '81? 3) car is way down on power, so i'm looking for obvious things like vacuum leaks. i find a fitting on the left side of the plenum between the 3 and 5 runners with about a 2" tube not hooked up. it would appear to be a vacuum port to something but what? 4) when running, it sounds as if there is a vacuum leak from under the drivers dash or the center console, anyone else heard a similar noise and what did it turn out to be? last question (for now), the sticker on the radiator shroud specifies plug gap of only .32-.35, why so low? the specs on my '81 are .40-.45 and both cars have HEI, i don't get it. thanks guys! :chevy
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Joined: Aug 2000
Posts: 14,130
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Re: c3 guy needs c4 help (clutchdust)
Ill try answering some questions....
As for the brakes wearing unevenly,it can be caused by the problems you mentioned but also dot overlook a bad brake hose or a sticking caliper on one side.
Ive always bled the brakes the standard way even with ABS as well,havent had any problems.
But if theres a specfic step for this year car,maybe someone will chime in and list it.
As long as you get the air out of the lines, it will be fine.The pedal will be good.
The vacuum port on the left side, if you mean the drivers side, DONT DRIVE the car if its not hooked up.
That pipe conects the PCV valve to the intake..there should be a curved rubber hose from the pcv valve to the intake (pipe) here..with that removed, thats a major vacuum leak and sucking in fresh outside air.
It would run leaner this way and not very good at all.
Also,For a TPI,to find other vacuum leaks, use carb spray and spray shots around the intake..when the rpm changes from the spray,you found the leak.
As for spark plug gap,follow the stickers specs for the factory type plugs.
If it says .35 then use that.Many people said they used .35 to .45 gaps with no problems.
These HEI set ups dont require much gaps to run well.When you add more powerful ignition parts,a module, coil and etc, you can try higher gaps then.
:)
As for the brakes wearing unevenly,it can be caused by the problems you mentioned but also dot overlook a bad brake hose or a sticking caliper on one side.
Ive always bled the brakes the standard way even with ABS as well,havent had any problems.
But if theres a specfic step for this year car,maybe someone will chime in and list it.
As long as you get the air out of the lines, it will be fine.The pedal will be good.
The vacuum port on the left side, if you mean the drivers side, DONT DRIVE the car if its not hooked up.
That pipe conects the PCV valve to the intake..there should be a curved rubber hose from the pcv valve to the intake (pipe) here..with that removed, thats a major vacuum leak and sucking in fresh outside air.
It would run leaner this way and not very good at all.
Also,For a TPI,to find other vacuum leaks, use carb spray and spray shots around the intake..when the rpm changes from the spray,you found the leak.
As for spark plug gap,follow the stickers specs for the factory type plugs.
If it says .35 then use that.Many people said they used .35 to .45 gaps with no problems.
These HEI set ups dont require much gaps to run well.When you add more powerful ignition parts,a module, coil and etc, you can try higher gaps then.
:)
