72 Chevy k20 350 won't start

[FrankieD]

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

I knew 30 was in there but was tryin to remember from back in the day. Still have a Dell Meter and an allen wrench on a flexable shaft for adjusting the points while it is running so you know I'm old

[72chevydump]

Ok so I tapped te key until both valves on #1 cyl were all the way up and the mark on the harmonic balancer was about an inch or 2 past the timing tab so I turned it back to 0(dead center on the timing tab). I could sorta wiggle both rockers so i knew they were both closed on comp stoke. I pulled the distributor cap and the rotor metal tab piece thing was pointing at 7 o clock. So I pulled all of my plug wires are started over with #1 wire going on the 7 o clock position on the cap. I followed the firing order starting with 1 and went in a clockwise rotation. I thought this is it here we go and nothing just cranks. So I pulled the #1 plug and had someone crank it while I check the spark. It is def yellow. So I assume I have a weak coil. So if my coil is weak and that is the problem why won't the spark it is giving off ignite? Is it getting to the cyl late and exhaust stroke already sucked out all the fuel vapors?
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[72chevydump]

Everywhere I looked sparkplug gap with points(what I have) should be .030-.035. Mine are gapped at .030.
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[FrankieD]

Should still run do your self a favor and get a new coil the gas today just don't burn like it did in the 70's

[72chevydump]

Ok so I got a coil. Installed it with the wire coming from the distributor to the neg on the coil and the other wire (I'm assuming 12v) to the positive on the coil. Still nothing just cranks. Didn't get to pull a plug and look at the spark yet.
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[FrankieD]

If the wires are correct and you are getting gas it should fire. Some thing happend when you installed the headers. Turn the key on and see if you have 12 volt to the coil then check the wire at the termanal block that has the small wire from the battery going to it and make sure it has 12V

[72chevydump]

The truck fired after the install that's why I don't know why it won't now. Could I have collapsed a lifter? When the motor is cranking its not a smooth crank it almost sounds and kinda feels like something is rubbing somewhere.
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[chevytruckluver]

even if you damaged something in the valve train on 1 cyl or even 2 it would still run.
It sounds like you have the dizzy and the plug wires correct. It will not start on starting fluid, still sounds like an ignition/spark problem. Did you check the voltage at the + term on the coil? Pull a plug wire off at the spark plug, then grab a spark plug and plug it into the wire, ground the plug to a good clean part of the engine or frame or a bracket, hit the starter and watch for a spark

[FrankieD]

Did you ever get it running ? If so what did you find

[72GMCK-2500]

Maybe theres no gas in it. My 72 k2500 wouldnt start or crank even with ether. Turns out my trusty fuel gauge was very incorrect. It read 1/2 tank and was empty!

[FrankieD]

Originally Posted by 72GMCK-2500

Maybe theres no gas in it. My 72 k2500 wouldnt start or crank even with ether. Turns out my trusty fuel gauge was very incorrect. It read 1/2 tank and was empty!

Hate when that happens

[old Chevy guy]

Just read this whole thread and now Im on the edge of my seat wondering what was wrong. If it didnt start just to throw in my 2 cents,if its a points distributer there should be 2 wires to the + side of the coil. 1 is from the ignition and the other comes from the starter and is a bypass to keep the coil voltage up while there is a starter draw. The starter cranking can drop the coil voltage down to 9 volts or less creating a weak spark in the start mode.Hence the second wire. If the ignition wire breaks the motor can start on the bypass but will die imediatly when you let go of the key. Hei is the way to go. Also if its points dont forget (everybody always forgets) the condenser can be bad and cause weak or aradick or no spark also. Hei is the way to go...sorry I think I already said that. Good luck and let us know what happend!

[72chevydump]

Hey everyone. Thanks for all your input. I have been so busy I haven't had time to work on it. Latest update I got a new coil. I haven't had the chance to try and start it and look at a plug to see if the spark got stronger or stayed the same. Quick refresher on what I changed.
Plugs, wires and coil.

Do points distrib just go bad? I can't even figure out why it doesn't even sound like it wants to turn over.

I only have 2 wires to the coil. 1 to the + and 1 to the - . I wonder if in the header install process I broke the wire coming from the stater to the coil. I'm pretty sure 1 wire goes from coil to distrib and the other goes down to a wiring harness. I THINK. But i am positive I only have 2 wires hooked up.

The tank was on fumes before I did the headers so I ran to the gas station and put 5 gal in it. The gauge reads half and after I put the gas in I only drove it 3 miles MAX. When I lookin in the carb an work the throttle I can see fuel squirt in.

Tomorrow I'm going to hook up a multi meter to the coil and check the volts, also I will look to see if I can find that missing 2nd wire that is supposed to be on the coil.

Thanks again everyone and keep the ideas coming this truck ain't gonna fix itself. Lol.
Quick question. Hei distrib- what are some good ones preferably in the cheaper price range?
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[old Chevy guy]

If your unsure about the coil wire you can always use a jumper right of the battery to the positive side of the coil,as a test. Just be careful because it will be wired hot and you wont be able to turn it off at the key with the wire on that way. As hei goes the factory ones are awsum and can usally be found at a resonable price. You might find one in the parts board here. Good luck keep us posted.

[FrankieD]

If you are having trouble finding the wire go back to post 14 and check the wiring diagram the wires are color coded. If you have trouble reading it go to view at the top of your computer and go to zoom and hit 400%. Good luck

[72chevydump]

Ok so heres what i found out today.

yellow wire going from coil to starter was cut in half so that wasn't even hooked up. I still didnt hook it up i just ran a jumper from + on the coil to + on the battery. the - on the coil goes to the bottom of the distrib. TRied to start it with the jumper hooked up but still no start.
Now on the starter. there is 1 big terminal and 2 small terminals. the big terminal, the wire goes to the battery. 1 of the small terminals isnt used and the other small terminal has a wire that goes into a mess of oily wire loom and electrical tape. I'm guessing that is my ignition wire that tells the starter to crank when you turn the key.

With the jumper hooked up i pulled a plug wire and checked the spark. with the jumper the spark was def stronger than without the jumper. but still no start.

So whats next guys? new distrib or what?

[old Chevy guy]

Not sure why it wont start but about the two small terminals on the starter,One has a bigger Purple wire that comes from the key switch and it engages the solinoid when the key is in the crank position your yellow goes on the other one.

[old Chevy guy]

Send me pictures of the truck maybe I should just come buy it. Just kidding...unless its nice.

[72chevydump]

IT'S ALIVEEEEEEEE!!!!!!

So I was under the hood working the throttle and lookin in the carb making sure it was getting fuel and it wasn't. And I noticed so orange rusty lookin spots in there so I pulled the line off the carb and cranked some fuel into a jug. IT WAS ALL WATER. It was more clear than spring water. So I pulled the line off the inline filter and drained the tank. I put 5 gal in the tank a while ago and the gauge read 1/2 tank. Well while draining it I bet I got a gal of water out. So today I went and got a new filter, a new gas cap( it was cracked and just jiggled, no seal what do ever) and a bottle of that water remover stuff. Put more fresh gas in it and filled the carb wit some gas and I touched the key and VROOOM she fired up.

It won't idle though. I have to hold it at 1/4 throttle just to keep it running and then it still dies. I'm thinkin the carb is gunked up. But man I'm extatic that it runs now.

I never cleaned a carb before so what does that entail?

Thanks so much for everyone's input. Hopefully I can get her runnin smooth and I'll be off hauling and dumpin on no time. Woooo I'm pumped.
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[72chevydump]

Oh yes and while I am holding the throttle it is running irratic. Popping and carrying on and then it dies. But it will stay running for like 30-45 sec then shut off but fires right back up
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[webfoot]

Sounds like a timing issue, that is a symptom of not enough advance.

Too bad you couldn't have gotten it running on water, I have lots of that and its cheap.

[72chevydump]

I never pulled the distrib. I know he wires are in the right spot. What else can I do to adjust the timing?
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[webfoot]

You might also be having problems with all the water that got in through the intake but you need to find out what your timing is set at, shoot for 10* btdc with the vac advance unplugged. Wires in the right spot is only a small part of the equation.

[FrankieD]

Probably water in the Float bowl, take off the carb and take the screws out of the top chech for any loose springs abd remember where they came from then turn it over in a pan see what comes out, shoot it up with some carb cleaner start at the bottom to make sure you clean the jets first. If you break any gaskets you will need to get a rebuild kit. If there is a tag still on it that you will need to get the right kit put it back on when putting it together.

[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