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Help my truck run better in cold weather...

7

'73 K5

1/2 ton status
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Feb 17, 2000
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I've got an open element K&N filter, Edelbroke 600 w/electric choke, Performer intake and Vortec heads, etc. Runs great in warm weather but completely sucks in cold weather. Is there anything I can do to help it out without switching any major components. My mechanic buddy said something about it not having any "crossover" and that hurts the cold weather driveability. I'm kind of a retard when it comes to this. What is he talking about? Something with the intake or heads I think.
What about using a snorkel style air cleaner assembly with that air tube thing that goes from above the exhaust manifold into the air cleaner opening. I'm not explaining this very well but I hope you all understand. Thanks.
 
Standard type heads and intakes have an exhaust passage that goes from one head to the other through the intake manifold under the carburetor, the exhaust (crossing over) warms the intake to help the fuel stay in vapor form till it gets to the cylinders, performance engines block off, restrict, or don't have this passage to prevent the heating of the air charge when the engine is at operating temperature and suffer the consequences when it's cold.
Is the engine alright once it warms up, or does it run bad all the time when it's cold outside?
 
Hey Ryan! Where you been? Haven't seen you around for a while. /forums/images/graemlins/tongue.gif
 
To add to 95 Silverado's comment above, the hot air is kept in the crossover during warm up and cold weather operation by a vacuum operated heat riser valve. Generally it is installed on the passenger side exhaust between the exhaust manifold and the exhaust piping.

However, I'm pretty sure that your cold weather/poor running issues are being caused by your open element K&N. You already seem to understand how the factory thermatic air cleaner works, so I'll assume that you understand WHY it's needed.

A couple of years ago I replaced a bunch of vacuum lines/tees, but I was missing one tee so I left the line to the diverter motor disconnected. When winter came around, it took me about a week to figure out why the truck was running like crap for the first 10 minutes of driving. After I smacked my forehead and reconnected the diverter motor to the vacuum system, everything went back to normal. /forums/images/graemlins/smile.gif

If I were you, I would start by ditching the open element setup and using the factory air cleaner during the colder months.
 
Well, its kind of like 2 stages. When the engine is cold AND its cold outside its real bad. Once the engine warms up, it gets alot better, but its still kinda sucky. Compared to summer driving at least.
 
Hey K30. Yea, long time--no see. I was out of a job for a while and I didn't have any money to do anything to the Blazer so I quit coming around for a while. It was torture to read about all the stuff everyone was getting when I was double poor. Then I got a sweet job and bought a 5.0 Rustang...which took my attention away from this website for a while. After I got used to the Mustang, then I got the itch to do stuff to the Blazer again...so now I'm back. Good to see you're still here and up to 596749594 posts. lol
 
I just put the same carb and intake on my truck. 85 Silverado with a 305. Is there some kind of adapter that you can buy to use the original air filter housing? Mine hits the carb. Also, in my original housing, there is a screen I guess you'd call it in there too right before the intake. Hard to explain. It goes filter and then the screen. It's round and just smaller than the air filter. what is this thing and can I cut it off somehow?
 
When you say adapter, all you want to do is raise up the air cleaner stuff higher so it doesn't hit the carb right? I've got a spacer on mine right now that I HOPE will work with the stock air cleaner setup. I can't remember where I got it, but its just this simple black ABS looking riser. I'm using it now to clear the carb linkages, choke, etc. As for the screen thing, I'm not sure what you're talking about...maybe someone else can help.
 
Todd 91 - Please start off by filling in your profile. Name, location and truck info is pretty important. We have members all around the world and one of us might live right around the corner.

Now, to answer your question, the "screen" filter is a charcoal pre-filter. Unless it's required to be there because of local emissions laws where you live, go ahead and rip that sucker off. Your engine breathes a whole lot better with it gone. Mine was simply glued onto the bottom of the air cleaner housing with some sort of strong silicone/glue......
 
Sorry for adding a question, but it is the same subject. My truck 87, 305 ran great all summer, now that it is cold, it bogs down when I accel. and then speeds up. Rpm's and everyting drop like in 2nd gear and then picks up again in 3rd. All suggestions are helpful. Once again it ran fine until the temp dropped.
 
With no crossover, (Vortec heads don't have a way to run EGR OR hot air through the intake) I'm not sure how you are going to be able to keep the carb warm enough. One thing I'd suggest is make sure you are running a 195 thermostat. At least the coolant passing through the intake will be warmer, and will transfer more heat than a colder thermostat.

Of course that may not be your problem at all, is your choke working correctly?
 
CanmoreK5-I thought I had that profile filled out already. Back to that after this post. 85 Chev Silverado, 305. I'll rip that screen deal off once I can find an adapter for my old cleaner. Sounds like the better way to go.
 
Yea, the choke is doing fine. The cold weather thing started after the Vortec swap. And I do already have a 195 thermostat. Any other ideas than the air filter assembly swap?
 
You are at a bit of a crossroads it seems. Running THERMAC may help, but as you can see in that setup, it is a fairly sizeable restriction to air intake when its in use...so it may help with keeping the thing warmer, but hurt you on overall power.

I really don't know what else to try if the choke is working correctly. You could always go to some type of intake that you can plumb hot air into the crossover, but thats a goodly amount of money and work, for not a WHOLE lot of gain.
 
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