I have an 87 z28 (305) with an edelbrock 4bbl carb. There are a few problems I'm experiencing.

1) It runs well enough but the idle will sometimes rises on its own. That is to say the rpms slowly go up. Usually this only happens in the mornings. If i tap gas after a minute or so, it will on occasion drop the RPMS down to..1700 after about 10 minutes of driving it idles somewhere around 500-1000RPM. When I bought the car I was told that the carburator needed to be tuned. If anyone knows how to do that, I would really appreciate it. Also what is the proper idle speed for that engine? I think I read it was 1000 RPM.

2) Second, there is a whining sound when the car is in gear. Almost like a supercharger whine. It's most prominent at 40 MPH. And the faster I go the higher the pitch. Sometimes if I let off the gas while I'm moving it will kind of...bounce almost. A friend of mine suggested the drive shaft might not be aligned correctly, I think that it might be something in the transmission. I say this because when in neutral there is no sound. Oh, btw it is a 5 speed manual tranny. The engine has 145,000 miles...

3) There is a check engine light on, and I got a repair manual for that, once I figure out what the code is that it's throwing I'll post it up.

4) The speedometer while driving likes to float. that is it'll stay at 40 a little then rocket up to 60 then bounce around. Probably just a loose cable, but I thought I'd post it up anyway. I am a novice when it comes to repair so any and all help is appreciated. Thanks very much in advance.

-Camel

 

1) are you using manifold vacuum advance? If not, check for vacuum leaks. If the motor is mostly stock you can use an 800RPM idle.

2) neutral while rolling makes no sound, (like if you put it from 5th to overdrive, clutch pedal off, still makes the sound)? Then yes tranny/clutch related.

3)do a search on ALDL. Use a paperclip to pull the codes.

4) cable driven speedo for that year? Might need some oil. Might be loose. Could be the whining sound actually. Pull the speedo cable out of the trans and see if anything is visibly wrong

 

thanks for the help, will try all those and post results. you'll have to excuse me..manifold vaccum advance? i'll look for a picture and see if i am. i didnt buy the edelbrock so i have no idea what model or features it has..edit: also to answer your question, yes if rolling there is no whine in neutral, but at low speeds there is a quiet knock almost when i'm slowing down. forgot to mention that one.

 

you've skipped the computer controlled carb, and computer controlled distributor right?
So you have a vacuum can on your distributor? Is it hooked up to a manifold or ported vacuum source on the carb?

 

i took some pictures of the carb. maybe you can show me what i'm looking for. i really am a novice, and this is my first ever camaro and carbureted car so bear with my lack of experience. pics in a second

 

here are some pics.

 

Everything "looks" to be set up properly. Doesn't look like a stock dizzy, or at least cap.

Edlebrocks have a fairly decent reputation for being "good out of the box." They aren't finicky like Holley's when it comes to having to tune them and getting them really dialed in. I've done a few on some friends cars and haven't tuned any of them and they run fine enough.

Has the choke (the black round thing with the red wire going to it) been properly adjusted?

Edit: as for the whine, is the noise noticable in all gears, just one specific gear?

 

no it hasnt. at least not that i know of.

edit: whine is noticeable anywhere between about..20+ MPH in every gear. including first, if i mash on the pedal.

 

That's a teeny carb...
And a very crowded engine bay.. holy...

ok, edelbrock carb - that shoulda flagged me at first.
Your ECM is somewhat useless now.
Your distributor, i'm assuming is the non-cc style? I didn't get a good look.. Does it have a vacuum can on it?

 

I.e. one of these sticking out of it:

 

I wouldn't worry about the check engine light, considering that now you've got an Edelbrock carb the computer doesn't have anything useful to do anyway.

 

well here's a picture of the distributor

and a picture of it at another angle and some more of the engine bay.


judging by the pic provided...doesnt look like it.

edit: as for the edelbrock...well it wasnt my choice. I'd prefer a holly.

 

That's a stock computer controlled distributor. It needs to be changed if you plan on keeping that carb.

 

hmm, but it doesn't look like the stock one either...?

If you can find a part #, or brand on it, maybe post that.. But if it's got an extra electrical connection on it (for the EST... rectangular 4 wire plug coming out of the back...), then you'll need to replace the distributor with a non-cc one.
This may be effecting the idle speed.. If you dist is doing weird things with the timing.

I think you've got #3 solved.

As far as the noise... hmm, first thought is that your tranny is screwed...?
Maybe post that question seperately in the tranny forum..

 

could you point me in the right direction for one?

Ok, CC means computer controlled correct? So that would mean i need to find one that isnt. Alright. Thanks for the help guys. I really appreciate it. Any other theories on my other problems?

 

I don't see a vacuum advance can. Unless it's out of picture. Dig around the base of the distributor cap. It would be quite obvious.

Here's my dig on the situation:

Unless it's hiding and not visible, you need a vacuum advance setup. What you're running appears to be ESC-based still (computer controlled). Go to Edelbrock's website or search around here, try to find instructions on how to dial the choke in (basically loosen 3 small screws and rotate the cap either clockwise or counter clockwise). Between those 2 things, that should fix the engine-related issues. After that, don't mind the check engine light, since it probably has to do with the ECM being pissed off because the original intake setup is missing and really has nothing to control.