'82 C10 Engine Identification / High Idle Issue

[keegxwill]

Hey guys! This is my first post and it's a bit much.. 
I recently purchased a 1982 Chevy C10 pickup. This is my first old vehicle to own and I have little experience.

I knew it needed a bit of work when I bought it, but it started to become overwhelming a few weeks ago. The more I'm learning and digging, I'm finding that the PO lied about various things, and neglected to mention others, and I'm figuring out more and more nonsense that's wrong with it and realizing I paid too much, but so it goes. I guess that's happens with these older vehicles sometimes.

First thing, I'm still not sure what engine it has in it. The VIN says that originally it came with a 305, but the PO said specifically that it was a 350. I don't care which it is, but I need to know for proper specification purposes.
The engine code on the pad under the alternator reads "V0905PAC". The thing is, I can't find any listing of a "PAC" engine code suffix. So far, I've changed the spark plugs and wires and battery with ones that work for either application, but I'm sure I can't do that every time. Is there another way to tell what it is?


I am having a problem I can't pin down. I have high idle in park and neutral. In drive and reverse, it idles normally. I don't have a tach, so I'm not sure just how high the high idle is, but I know it's more than a couple hundred rpms. There's no smoke from the exhaust. Doesn't miss at any speed. Runs well otherwise.

I had originally believed that the problem lied within the carburetor, but I just replaced the carburetor with a brand new one and am having the same problems. It might still be carburetor problems, and my lack of common sense that is complicating the situation. I'm not sure. The carburetor is an Edelbrock 1406.
It's on an Edelbrock Performer (I think) intake manifold.
When I replaced the carb, I also put on an Edelbrock 2732 carb adapter, because I read somewhere it needed it, and it didn't have it already.
Vacuum guage read 15 with old carb before adapter.
It reads 17 with new carb and adapter.
I cannot find any vacuum leaks.

I have adjusted the IMS on each side until it bogs down and then I back it off to achieve maximum vacuum, but my idle speed screw is backed almost all the way out, and the idle won't go any lower. Fast idle cam is definitely disengaged.

Like I said, I have limited knowledge, but I want to learn. Does this sound like carb issues? Timing maybe? Ignition? I'm shooting in the dark here.

[VileZambonie]

Recheck the numbers listed there and get the casting number on top near the bell housing. What's your VIN#?

As far as your high idle, you must have a vacuum leak if you are not on the fast idle cam and the throttle is backed down. Are you sure the throttle cable is allowing the linkage to return? Did you hook up the brake booster to the port in the back of the carb?

[keegxwill]

The numbers on the pad under the alternator are correct. From what I've read, there are usually two sets of numbers, but I only have one set.

On the top of the block near the bell housing? I'll check there when I get back to the truck.
The vin is 1gcdc14h4cs142889. The H in there implies it's a 305.

I mean, I thought it was a vac leak. I can't find one, though. I've sprayed all over the thing with WD40. The brake booster is connected. It's a pain to Screw in with the metal line it uses. Yea, I've disconnected the throttle cable altogether. Same deal.

[Irish_Alley]

how much vacuum line is connected to the engine? if you unplug a manifold vacuum hose it should raise the rpms or kill the engine

[philo_beddoe]

I also had a high idle, the speedo cable had a kink in it.  Quick and easy to change, $19.95.  Vilezambonie mentioned to make sure that throttle is returning all the way, i totally agree!  If not a vac leak and the throttle is good (i had to replace throttle spring too).  Could just be an idle screw adjust?

[philo_beddoe]

.......and,,,test what irish mentioned.

[philo_beddoe]

Choke?? High idle screw??

[keegxwill]

I have PCV going to PCV port on carb.
Manifold going to manifold port on carb.
Vacuum advance going to timed port on carb.
Brake booster going to brake booster port on carb.
Manifold going to wipers (I think).

I've replaced PCV valve and all the aforementioned vacuum lines.
This is probably a dumb question- should I have any more? I've done my best to go through and reconnect anything that I've found capped or unplugged, but I feel like I find something else new everyday.
If I pull the manifold to manifold, it idles way bad, but doesn't kill it. Could that mean there is a leak and it's getting air from elsewhere?

I also had a high idle, the speedo cable had a kink in it.  Quick and easy to change, $19.95.  Vilezambonie mentioned to make sure that throttle is returning all the way, i totally agree!  If not a vac leak and the throttle is good (i had to replace throttle spring too).  Could just be an idle screw adjust?

This all started about the time my speedometer started bouncing around!
Does the speedometer affect idle? The problem I had was it started bouncing in 1st, then 1st and 2nd, then it stopped working altogether. I checked the gauge with a drill and it worked, so I replaced the speedometer cable (which looked alright) the other day and the little plastic driven gear (which had minor wear). I drove it around and could hear the cable spinning behind the gauge, but the gauge didn't move. I haven't pulled it all back apart.

I guess I just thought assumed the problems were separate. ..you know what they say when you assume something. 

Otherwise, high idle screw is backed out enough to make the choke sit real well. Choke took me a few weeks to adjust, but this morning it cold started flawlessly for the first time.

[philo_beddoe]

I'm a little rusty on all the ports, one of the smart ones can answer, like capt kaos....among others.

Sounds like your driving my truck!!  Had the same problem, i heard a funny squeaky sound, thought it was coming from the wheel. " Do you hear that, its a funny squeaky sound" remember the old lady from Christmas Vacation?  Ok, enough foolin around.

My cable was a little warped, had to replace. My needle bounces, but thats another very long thread. Must replace guage to stop bouncing.  No your speedo cable wont effect idling.  Could be vac leak, but doubtful.  Sounds like possible mix up of hose connections, maybe.

[VileZambonie]

Manifold going to wipers (I think).

What

[Irish_Alley]

I have PCV going to PCV port on carb.
Manifold going to manifold port on carb.      ≤<<<<<<<<how's this work?
Vacuum advance going to timed port on carb.    <<<<<< for a better running engine run this to manifold vacuum
Brake booster going to brake booster port on carb.
Manifold going to wipers (I think).  <<<<<like vile, what

[philo_beddoe]

Manifold to wipers??,  that one kept me up all night too!

[keegxwill]

I, in all my newb-ness, got some of that wrong. To clarify, I have included photos.

From elsewhere to carb I have:
- PCV going to PCV on carb.
- Brake booster going to rear port on carb.
- Vacuum advance going to timed port on carb. (Which I will change to full manifold port on carb today.)

From the intake manifold port behind the carb I have:
- Steel line going to transmission.
- Line going to manifold port on front of carb.
- Line going to deal on passenger side firewall, which turns into electrical connections, which go into firewall. What is this?
- Line going to what I thought was wipers (I know, I know..). It goes to a deal on the driver wheel well. I’m missing a wiper fluid tank deal, and I didn't pay much attention to it, so I figured that’s what that was.. Sorry. What is this?

Here are photos of everything for clarification.
http://imgur.com/a/Na1ct

[keegxwill]

I FOUND THE VACUUM LEAK!   

The steel lines going to the transmission, right before the modulator had a small pinch in it. I guess I just missed it the first time I checked. Replaced the line, retuned the carb and she runs like a dream now. Thank y'all for all your help!

Just wondering, though, for the sake of gaining knowledge, what are the two deals that have the vacuum hoses going to them? The one on the passenger side firewall and the one on the driver side wheel well. I know you experts must have an idea. 

[philo_beddoe]

I'm with you, i was wondering what they are also.  Someone will reply what they are soon.  Stay tuned...