72 Chevy k20 350 won't start

[old Chevy guy]

Is it popping through the carb? You said something a ways back about it ticking or haveing a rocker noise. could have a bad cam and has an exhaust valve that isint opening. Ive had pushrods that pluged up. That how the oil gets up to the top and lubes the rockers. So the pushrod plugged and no oil came up and the top of the pushrod wore out and sounded like the cam was bad cause the pushrod was too short. Actually had that happen twice on 2 diffrent motors. Diffrent pushrod and rocker arm fixed it. Not saying thats it but something else to look at. Is it ticking now when running

[72chevydump]

Ok. It's in time. The vacuum for the brake booster wasnt hooked up so that was a big
Problem. Now I think I have the plugs fouled cause it's smoking alot of white smoke and won't idle for longer than 30 sec. I really should clean the carb too I just know if I take it off that when i put it back on it will leak. Is there anything I can buy that you spray in the carb while it's runnin to clean it out?
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[FrankieD]

Every thing might just be a coincidence and you have a deeper problem. White smoke is normaly caused by antifreeze or water Blueish would be oil, black would be gas, are you getting a lot of moisture out of the exhaust? Check the oil see if there is any bubbles or anything that looks like moisture. Take the oil fill cap off and look at it and see it it had any moisture on it . If you have any of these before you do anything else I do a compression test.

[old Chevy guy]

If you go to do a compresion test when you take out the plugs you may find one or more that is either wicked clean or rusty.That would be an indicater you might have a bad head gasket.If theres lots of white smoke see if it smells like antifreeze.

[72chevydump]

It was having rough idle and smoking alot until I hooked up the vacuum line from the booster and then the smoke went away for the most part. I think it needs to just get ran and all cleaned out from sitting. Maybe a fresh oil change since the valve cover was of for a while and with rainy weather and morning dew. Moisture was def getting on the rockers. The hood was closed but when it's misty or raining that moisture still gets everywhere.

Anyone ever use that seafoam stuff? I did some research and seems like it wouldn't hurt to dump some down the carb to really clean everything up.
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[FrankieD]

Seafoam is great stuff, you can get it warmed up pour it in the carb till it starts smoking and it will fog the neighborhood then shut it down and let it set a while then start it back up and drive it that will loosen up the carbon on the pistons and heads. You can also pour it in the gas to clean the carb.

[72chevydump]

Yes. I think I'm going to try both methods. Add to the gas and the carb. Along with seafoam I'm gonna get new plugs too. What plugs do these motors like? Do the favor a certain brand?
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[FrankieD]

AC seem to work the best

[72chevydump]

Hey guys sorry for the time lapse. I just rebuild the carb. Full of white muddy gunk. Just put the carb back on and fired her up. Started right up ran for 15 seconds and then shut off. Fired right up again ran for 15 sec and shut off. Started it again fired up went to give it some throttle and it just bogs and dies. So what now?
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[FrankieD]

Originally Posted by 72chevydump

Hey guys sorry for the time lapse. I just rebuild the carb. Full of white muddy gunk. Just put the carb back on and fired her up. Started right up ran for 15 seconds and then shut off. Fired right up again ran for 15 sec and shut off. Started it again fired up went to give it some throttle and it just bogs and dies. So what now?
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Is the choke set? when push the peddel to the floor be for starting cold it should be open between 1/8 to 1/4"

[72chevydump]

Yes. When I work the throttle under the hood the front flap only opens a little bit.
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[FrankieD]

Originally Posted by 72chevydump

Yes. When I work the throttle under the hood the front flap only opens a little bit.
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When you go wide open the choke plate should be open about 3/4" to 1"and the front throttle plates should be wide open. Every time you pump the throttle you should see gas squirt in to the carb. When you set the choke the fast idle should also set it has an adjusting screw on a cam lever, it that isn’t high enough that will cause the engine to die.

[72chevydump]

Alright everyone. She fires up and idles. . Now the only thing is it doesn't idle down. It runs at high idle or fast idle whichever you wanna call it. I had it runnin for about 15 min and then went to test drive and even after driving around the lot a few times when u come to a stop it still idles high.
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[webfoot]

Check the fast idle cam on the passenger side of the carb. If it is stuck in a 45 degree angle or so it will idle high. If it is warm click it down so it is parallel with the base of the carb and it should idle down. On mine it takes a good blip of the throttle to get it to idle down.

[72chevydump]

Originally Posted by chevytruckluver

Did'nt see wher you said if it were an HEI dizzy or not but if you do have points the gap should be .017 not .030 If you were to use a dwell meter to check the points the dwell should be set to 30
from what I have read here about your problem its sounding like a ignition problem, if it wont start on starting fluid it is probably not a getting spark.
good luck

Originally Posted by webfoot

Check the fast idle cam on the passenger side of the carb. If it is stuck in a 45 degree angle or so it will idle high. If it is warm click it down so it is parallel with the base of the carb and it should idle down. On mine it takes a good blip of the throttle to get it to idle down.

I will check the cam tomarrow. I know my buddies truck an 85 k20 with the 350 you "blip" the throttle and it idles down but on this it won't. That's why I don't know if something is stuck or what cause it's not doing what it should.

Summer is now pretty much here so can I disconnect the choke so it doesn't high idle at all? I'll just let it warm up a little longer.
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[webfoot]

These things get wore out. On my old (original) one I'd have to get out and manually kick it down for it to work. On the newer one I rebuilt it will idle high until I blip it pretty good. Removing the choke will not remove function of the fast idle cam. Or in your case, possible dysfunction.

[FrankieD]

You might just need to turn the fast Idle screw out

[72chevydump]

With the truck running I was playing around with the adjustment screws in he front and it didn't seem like anything was changing. At idle with the engine warm the front flaps on too of the carb are wide open. Even after I shut it off they stay wide open. What could be causing this? Also I took it for a test drive and it seems like all the power isn't there. Almost like the 4 bbl isnt kicking in. Any input?
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[webfoot]

It probably doesn't much good to play around with them if you don't know what they are doing. A good starting point 2 turns out from all the way bottomed out. In leans the idle out, out richens it. The "front flap" of the carb is the choke flap, and this should be open if the engine is warm. the secondary flap is vacuum operated and will not kick in until higher RPMs.

Power being down can be timing related or how the carb is set up. It takes some adjusting to get the secondaries to come in correctly.

[72chevydump]

When I was playing with the front screws I counted my turns and made sure to adjust them back to were they were after not noticing any changes. I will adjust the dizzy to try n get it to idle better.
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[webfoot]

Before you go adjusting it, do you know what it is currently set at?

[Cannonball1]

Adjusting the idle speed mixture screws won't help as long as it is idling so high. You need to get the RPM's down under 800-900 for them to have any affect.

[72chevydump]

Originally Posted by webfoot

Before you go adjusting it, do you know what it is currently set at?

I'm not sure. The only way I would be able to check is how many turns in it goes. Is that how I check?
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[72chevydump]

Ok here's the Situation I'm in.

After the truck is warm it's idling high. If I turn the dizzy to get it to idle better when I work the throttle it pops back through the carb. So with the idle sounding pretty good I tried adjusting the front 2 screws. What are those 2 screws? Because it seems no matter where I turn them it doesn't change anything? I think im close I havin it running good it just needs some fine tuning.
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[chevytruckluver]

Originally Posted by 72chevydump

Ok here's the Situation I'm in.

After the truck is warm it's idling high. If I turn the dizzy to get it to idle better when I work the throttle it pops back through the carb. So with the idle sounding pretty good I tried adjusting the front 2 screws. What are those 2 screws? Because it seems no matter where I turn them it doesn't change anything? I think im close I havin it running good it just needs some fine tuning.
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Step 1 get a timing light and set the timing, then tighten the dizzy.
Do not use timing to adjust idle speed
Step 2 make sure you have no vacumm leaks or misfires (any problems need to be fixed before you can proceed further) then adjust idle speed
After you have the idle speed set on a warm engine then you can adjust the 2 screws for the idle mixture. These screws will not have an effect on anything at speeds above idle.
Step 3 recheck timing
Step 4 let us know how it's going after that
Good luck
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