Hello to all !

As I said in my introduction, my 1987 C4 used to work like a charm, it was just perfect.

About a month ago, I took it in to a mecanic to change a ball-joint. When the mecanic came back from his "test drive" (turns out he drove 60+ miles), he told me the car was leaking oil really bad (even though it never lost a single drop in my garage...)

So I went up and ordered the 2 oil pressure switches, and also bought new plugs.

When I got the car back, it ran horribly; at least 2 cylinders didn't fire at all, the car smelled awful, and I kept hearing explosions in the converter. So I took it back in, and it turns out 2 of the plugs were bad.

While I ordered the new set of plugs, he put the old ones back in, but the car still ran less than perfect (several misfires, reduced power, a lot of shaking), so I decided to order new spark plug wires as well.

When he put it all in, it still ran the same, so I decided to change the distributor cap & rotor (it was suggested to me that bad plugs could damage a distributor cap?).

I changed it myself and found the car was running a lot worse after the repair (even though I carefully removed one wire at a time to avoid mixing up the firing order, and put the rotor in the exact same position as the old one was).

I found out that I had accidently rotated the cap while removing the screws, and by moving it back to the way it was the car runs better but not perfect. So I'm wondering if maybe the mecanic also rotated the cap to access the oil pressure switches, which would explain the misfires that appeared.

If so, can I through trial and error set the ignition right by rotating the cap millimeter by millimeter ? Currently the car runs at 600 rpm when put in "D" and 1000 rpm in neutral, which seems a tad high...

Thanks in advance for your help !!!

 

Have You ever watched the old American Movie from 1986 starring Mathew Broderick & other famous 1980's movie stars..............

Ferris Bueller's Day Off.

Parking lot attendants in Downtown Chicago take that Beautiful Vintage late 1950's- early 1960's Ferrari GTO for a "Joy Ride"...........
They get the car Air born too.............

I seen that movie in theaters in 1986 in high school...........

That was the most talked about scene in movie for some time to come.

And when that kid kicked the front bumper with the GTO Ferrari in reverse gear trying to get the mileage odometer down too..........

Car flew through the glass garage backwards & crashed 50 feet below into rich North Side Chicago's wildlife nature area below...........

Your stories & testimony this morning>>>>>> what likely happened to your Your C4 Corvette brings back flashbacks from that movie this morning.

60 mile test drive ?

He brought your Corvette back Broken & Hotrod beat up.





Brian

 

You can't change the timing without loosening the bolt at the bottom of the distributor shaft. I don't see how you could move the cap it is screwed in place.

 

hey loony , first of all you need to change your mechanic, i think this is happening
if you were able to rotate the cap maybe you are rotating the whole assembly
and your mechanic left the distributor hold down bolt loose ! please put the correct timing
(and you will need to disconnect the tan wire near the booster) its 6° on your automatic vette ..i think this is what's going on since you noticed a change when you rotate the cap ...

 

I recently watched that movie, and the ressemblance is indeed stricking
It hurt me to see that beautiful Ferrari getting beaten up likje that
even moreso with my vette !!

It did seem weird and hazardous to be able to move the whole assembly so easily...how do I know how to adjust it to 6° ?
Where is the hold down bolt located ?
Thanks!!

 

you need a timing light gun, do you have one ? try not to drive your car like that
when you get the light let us know , you need to unplug this before attempt any adjustments :
you will need a distributor wrench as well

 

The car is staying in my garage until all of this is sorted out.

I will try and get myself the two tools you speak of. I've heard of them, what's their use ?

 

check this video, the wrench is used to let the distributor base loose so you can rotate
the whole assembly , with your timing light gun you need to aim at the timing tab located on the pulley check this videos for reference :

your wire is on the opposite side


check this one to understand better

 

Interesting links

So I won't be able to set the timing right without these tools right ? I couldn't do like on the second video and try setting it "by ear" by slowly turning the distributor ?

Is the operation you described a complicated thing to do ? (I mean without risking to screw everything up :o)

This is all new to me and I appreciate the help

 

do it right do it once !

i can adjust timing in less than 5 minutes, its very easy
let us know

 

Alright, I'll get the timing gun and try to do this next weekend
Fingers crossed it'll solve all this !

 

i hope so , if you don't want to spend the $ you can rent it or borrow one
but they are cheap and its good to have your own tools , you might want to adjust
timing in the future again for whatever reason / upgrade . . . etc

 

I agree, it's probably better to buy one; after all I've decided to start doing basic maintenance work myself, so I might as well buy the tools progressively seeing as though shops where I live cannot be trusted...

 

Exactly wise move, you'll save a good bunch of $$$ in the long run !

 

You don't need the tool to CHECK timing, only to change it if it's not right. Check it with a timing light and then you'll know if you need to adjust it.

You mention turning the cap around. The CORRECT way is with the wiring (for the power, tach, etc.) on the driver's side.

I'll bet a buck or two that your spark plug wires aren't all in the correct holes in the distributor cap. Here's a little diagram I made. I laminated it and keep it in my toolbox:

 

I checked with the 87' shop manual to be sure that all the spark plug wires were in the correct order, but I'll double-check next saturday with your diagram just to be sure.
But if that were the case, wouldn't the car be running a lot worse ?

 

yes, terribly worse

 

I have the same problem my time is off. I will also try to fix this weekend.

 

here at my office video like are blocks. any body can post the url of this videos so I can see on my smart phone

 

any more details on how to turn the distributor. where is the screw that I supost to turn. more pictures will be very welcome