Want to build a good horsepower, good fuel economy engine for a 1978 c20 with stock 350. I don't know much and need help.

[Quinn_Hanifan]

I took a picture and some videos but im having a hard time uploading those

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[Quinn_Hanifan]

the top one, i tried your pencil trick and it worked for a bit but the engine still died when I left it to idle like It does normally

 

[Ricko1966]

the top one, i tried your pencil trick and it worked for a bit but the engine still died when I left it to idle like It does normally

The top one are the secondary air doors and are not supposed to open when you step on it only when the engine is drawing sufficient cfm. The choke is the lower one and it is open.

 

[Quinn_Hanifan]

The top one are the secondary air doors and are not supposed to open when you step on it only when the engine is drawing sufficient cfm. The choke is the lower one and it is open.

Ah okay

 

[Ricko1966]

How far have you driven this truck at one time. Has it ever seen 30 minutes continuous use?

 

[Quinn_Hanifan]

most certainly, the first drive home was over an hour, and when it was running better I've driven decently far, or for at least a while.

 

[Ricko1966]

K, so it doesn't get hot in 30 minutes of driving,that's a good sign.

 

[Quinn_Hanifan]

The temp gauge has always stayed under half, mostly staying at a quarter when driving for a while

 

[Ricko1966]

How did your current problem start?

 

[Quinn_Hanifan]

well thats what im trying to figure out, I'm not quite sure. I'm just trouble shooting at this point.

 

[Ricko1966]

Trouble shooting? Check compression,check vacuum reading, pressure test the cooling system or at least try to find an external coolant leak and read your old plugs.Look hard for vacuum leaks,lines off etc. Pull and plug the inlet hose at the fuel pump see if it runs good for a minute,locate the carbureator vent fill the carb through the vent with a mustard bottle, dish soap bottle full of gas see ifvit runs good for 30 seconds that way.

 

[CountKrunk]

How can you tell it's drinking coolant? You've been keeping an eye on the expansion tank?

Have you ever changed the oil? What does the oil look like?

 

[Rusty Nail]

Def gonna need moar pix??

 

[Quinn_Hanifan]

How can you tell it's drinking coolant? You've been keeping an eye on the expansion tank?

Have you ever changed the oil? What does the oil look like?

i have done all fluid changes and filter changes, including a coolant flush. oil got pretty dirty fast but I just added a couple of quarts because it was concerningly low. the expansion tank is what I noticed, it was pretty much empty even though I added more coolant to the proper level and such only a couple of weeks ago. no leaks or dripping fluids from anywhere that I know of.

 

[Quinn_Hanifan]

Would the timing have anything to do with the idle? i know when I add throttle just a bit it smooths out so that's why I thought it was the carb, but could it simply be timing?