sudden loss of power?

[countryboy279]

So i have a 1978 gmc k1500 pick up, 4x4,350,th350 trans.  waas driving to the store the other dday
and stopped at the store put the truck in park left it running came out five minutes later put it in drive and left when i was driving home i noticed it sounded a lot different and that it don't have as much power as it did it feelss like it only has have the power it did i was riving in snow and ice could s
Any help would be appriciated

[rich weyand]

Do you still have the thermostatic air cleaner on the engine, or is it one of those "two chrome pie plates" open-element deals?

[countryboy279]

It had the two chrome pie plates with the air filter in between and it had a rubber hose running from the bottom plate to the exhaust manifold but previous owner removed ot

[rich weyand]

The problem might be carb ice.  The big clue is that it was snowing; that is, that the atmosphere was condensing and freezing both at the time.

Read the first part of this thread:
http://forum.73-87chevytrucks.com/smforum/index.php?topic=27239.msg226597#msg226597

That open-element stuff is great for southern California, where they started.  For any place where it gets cold, not so much.

The nice part is that it's easy to pick up a thermostatic air cleaner.  People making mods (and who don't understand the issue) all go with the open-element thing, so you can find the stock air cleaners at the salvage yards.

The clincher will be if, after it warms up in the garage or outside, the next time you drive it, it's fine.

[countryboy279]

I let it warm up for about 20 minutes today before driving and it it still does it would it help if i replaced the hose that was removed because there are no salvage yards where I'm at and i have the hose in my tool box

[rich weyand]

Any heat to the carb will help if that is the problem.  Where was it parked over night?  What was the temperature?  Can you park it some place warmer?  Even an unheated garage will be warmer than outside.

Also check that the choke plate is opening all the way once it is warm.  If, for example, one of the wires falls off or loses contact with the choke, you will get the same symptoms you are seeing.

[countryboy279]

It was parked in the parking lot in -20 degree weather and it has been at least -10 degrees during the day and i don't have a garage to park it in also does the house provide heat from the exhaust im kind of new to this stuff

[rich weyand]

The heat stove is a sheet metal box around the manifold that warms up air for the carb.  The stock air cleaner has a door on it that either pulls air through the snorkel or, if it is cold, through a pipe that connects the bottom of the snorkel to the heat stove.  It heats the air going into the carb so the carb doesn't ice up.  The issue with icing is because liquids absorb heat when they evaporate (like sweat on a hot day; gasoline on your hands feels cold as it evaporates), and so the gasoline being used by the carb tends to refrigerate the carb.  Wrong atmospheric conditions, you get icing.

Check that the choke is opening all the way as well.  Run the engine for fifteen minutes (or just have the ignition key on for fifteen minutes), and then pull the top off the air cleaner and see if the choke plate is still shut (horizontal) or if it has opened (vertical).

Which carb is it?

[countryboy279]

Thanks for the advice i'll check it out and post also i don't what size of carn all i know. is its an edelbrock

[rich weyand]

That's OK, that's all I needed.  Check that the choke is opening after fifteen minutes.  Could be stuck or iced, or one of the wires came off, or the choke fuse blew.

[Irish_Alley]

Not to distract you from rich but do you have a catalytic converter?

[rich weyand]

Not to distract you from rich but do you have a catalytic converter?

1978 K-10 was the last year exempt from cats.

[countryboy279]

Yeah I don't have cats

[Irish_Alley]

Wasn't sure if someone put one on. Disregard lol

[rich weyand]

It was parked in the parking lot in -20 degree weather and it has been at least -10 degrees during the day and i don't have a garage to park it in also does the house provide heat from the exhaust im kind of new to this stuff

I just spaced into this.  Do you live in Minot or Fargo or something?

Whether it is the immediate cause of your problems or not, you need to put the stock air cleaner setup back on it.  Without carb heat, it will always run poorly in cold weather, and will run really poorly below 20*F.  All you need is the thermostatic air cleaner (with a working vacuum operated door and thermostat), the heat stove on the manifold (which it sounds like is still there), the heat riser pipe, and some vacuum line.  The air cleaner goes on with the heat riser pipe down to the heat stove, and the vacuum line goes from the thermostat to a vacuum port or t-fitting on a vacuum line.  That's it.

In the meantime, it would be really good if you could get it somewhere where it could thaw out.  Have you got a buddy with an attached garage where you could borrow a stall of his garage overnight?  An attached garage runs warmer than the outside due to capturing heat loss from the house.  Or maybe somebody who works at a garage or some company with an overhead door where you can get it inside over night?