1980 SBC 350 w/Quadrajet Carb

[alfredoleffew]

Hi Everyone,
I am trying to get my 1980 C10 Big10, SBC 350 w/quadrajet carb to start. It had been sitting in my neighbors yard from the early 2000's before I bought it this year in April. I've changed everything in the ignition system (plugs, cap/rotor, ignition cont'l mod, coil and plug wires) but I cannot get it to fire up. It does crank and build vacuum but then when I give it gas, it poofs out of the carb and the engine sounds different as its cranking. I checked the timing using the timing mark and checked the position of the rotor to verify TDC. It was very close to TDC so I adjusted it a little bit but still no luck.
I read that the ring on the harmonic balancer can come loose, hence giving an inaccurate view of TDC. Its getting fuel as I have changed the internal filter and fuel pump to carb line temporarily with rubber fuel line.

Any advice?

Also, my dad who once owned an '88 K-5 w/a SBC350 told me to check all the vacuum ports on the quadrajet because they could be contributing to it not firing up. Everything is connected/plugged except the hose in the photo that comes out the back of the carb and into a metal line the turns forward. I also would like help with routing the vacuum lines to the correct locations please.

 

[Trucksareforwork]

If you pour a little gas down the throat of the carb, you can help rule out the carb as an issue. The engine should at least fire with gas poured into the carb.

If you are getting some backfire through the carb, I would bet it's a timing issue.

But, with an engine that has been sitting that long, I would spring for new plugs and at least test the wires for resistance with a multimeter.

Then, I would try to start the motor with my friend on the key and one hand on the distributor so I could find a sweet spot on timing while its cranking. I'd dribble a little gas in it and see if it can fire. Then I'd try to sort the carburetor.

I doubt the harmonic balancer is off. That's a low-probability issue at this point.

 

[alfredoleffew]

If you pour a little gas down the throat of the carb, you can help rule out the carb as an issue. The engine should at least fire with gas poured into the carb.

If you are getting some backfire through the carb, I would bet it's a timing issue.

But, with an engine that has been sitting that long, I would spring for new plugs and at least test the wires for resistance with a multimeter.

Then, I would try to start the motor with my friend on the key and one hand on the distributor so I could find a sweet spot on timing while its cranking. I'd dribble a little gas in it and see if it can fire. Then I'd try to sort the carburetor.

I doubt the harmonic balancer is off. That's a low-probability issue at this point.

Great stuff, thank you.

 

[brooksman9]

Is the port capped off on the back where the brake hose hooks up?

 

[alfredoleffew]

Is the port capped off on the back where the brake hose hooks up?

It’s connected to the power booster

 

[fast 99]

If you pour a little gas down the throat of the carb, you can help rule out the carb as an issue. The engine should at least fire with gas poured into the carb.

If you are getting some backfire through the carb, I would bet it's a timing issue.

But, with an engine that has been sitting that long, I would spring for new plugs and at least test the wires for resistance with a multimeter.

Then, I would try to start the motor with my friend on the key and one hand on the distributor so I could find a sweet spot on timing while its cranking. I'd dribble a little gas in it and see if it can fire. Then I'd try to sort the carburetor.

I doubt the harmonic balancer is off. That's a low-probability issue at this point.

Or an intake valve sticking, any valve train problem such as flat cam broken valve spring, plug wires crossed. Does it have the small TBI distributor, did you get a Delphi cap and rotor? Some off brands will crossfire inside the cap. Does it crank even? When starter gets to a low cylinder or one not filling completely, it will speed up.

If timing is suspected bring engine up to top dead with a breaker bar and #1 plug out. Insert a screwdriver or long 1/4" extension in that hole. When piston stops advancing up should be near top dead on the damper. Look at rotor, is it pointing at the tower on #1?

 

[GTX63]

My first question is why did the previous owner stop driving it?
If for the sake of discussion, there were no mechanical issues when they parked it 20 years ago, things happen. Rings and valves can stick, needles and seats gum up, floats fail, etc. Compression may be low and mislead some to believe the motor is worn out when it just needs a little exercise.
The short and simple method is check for spark, and remove the fuel line to the carb; do not use the contents in the gas tank. Get a boat tank or a 5 gallon jug with fresh fuel.
I'd advise to not use starting fluid or brake clean, etc on a motor that has been sitting that long. Use some 2 cycle fuel with a little transmission fluid to help lubricate the cylinder walls.

 

[alfredoleffew]

After checking the timing over and over again, I finally got her to fire up. I set the timing mark to TDC once again and something told me to recheck the rotor (for the 5th time). Behold! 180* out of position. I have no idea how this happened but she fires up.
Now I have to move to the radiator after I dented it and caused a hole. I may as well change the proportioning valve since it’s stuck and without the radiator, it’ll be easy to access.