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Thread: Fixed my 1980 Chevy Silverado, now it won't start. Changed Spark Plug Wires.

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    Fixed my 1980 Chevy Silverado, now it won't start. Changed Spark Plug Wires.

    I'm trying to get a 1980 Chevy Silverado that has been parked for two years running again. (305 or 350) V8 2WD. It showed up in running condition but not good running condition. It would not pass inspection. I filled the dual 20 galon tanks and immediately found a leak. I dropped the tanks and replaced one. I was encouraged when the engine started up again after I installed two new sending units, new fill and vent hoses and new fuel lines. I got some lights to start working again and then my uncle the "Mechanic" told me I needed new spark plug wires. They were charred from having been left up against the manifold but the truck was still starting and running. He's advanced in years and no longer works on cars himself but I took his sagely advice anyway. He swears I have a 350 engine in this thing but the VIN says I have a 305. I can't tell the difference. I can't find the engine casting number but I'm still looking.

    I bought a set of bosch precut spark plug wires based on his 350 assumption and began to switch out cables. I followed instructions and did only one at a time. The very first wire had a matching length cable I could use. The very second cable I pulled was two inches shorter than the longest and two inches longer than the next shortest. I thought my uncle got the engine wrong. So I called the parts store and they said that was the right box for either engine. I packed it back up and returned it and instead got a set of universal spark plug wires that could be cut to length. That was an adventure in and of itself. After I managed to find the right kind of crimp-er for ignition wires and a you tube video teaching me how to use it I capped and booted all my wires.

    Next I located the firing order for a v8 chevy engine. 1-8-4-3-6-5-7-2 turns out it's the same for either 305 or 350. The starting position is the 6:30 position in a dist with points and 5:30 in an HEI dist. Doesn't matter though, I've checked and rechecked my cables and I've plugged them in using both starting positions. It started one time and ran rough. It would only stay on if I kept the gas floored. If I tried to let it idle it died. Never started again. It turns over but won't start.

    The one time it did start the order of my caps was wrong. Being new to do-it-yourself repairs I misunderstood the schematic. I put plug 1 in the starting position and then going in a clockwise direction plugged in the remaining cables in their cylinder numerical order. When you stop laughing realize that that's the only time it started. Someone explained the diagram to me and the firing order and now the cables are correctly aligned according to the firing order. Now, it will not start at all. Turns over and whines like the Millennium Falcon trying to escape Hoth but it simply will not start again.

    I ran out of daylight and didn't feel like breaking out the floods.

    I will locate the engine casting number and confirm my engine type when I have daylight again. Then update this post.
    I haven't removed the distributor.
    I haven't messed with the timing.
    I just changed the wires, capping and booting a universal set myself.
    It started and ran with the original burnt wires. Wish I'd left them alone now. Any help you can give me will be greatly appreciated.

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    New wires are a good ideal. You just have a lot of Gremlins to chase down before you are done.

    Check to see if the distributor wire is plugs in good, and clean. A bit of dielectric grease wouldn't hurt.
    Now check to see if the distributor is plugged in good and clean. One is a power wire from the harness the other is from the cap to body of dist.

    If it doesn't fire up. Turn it till the timing marks line up, pop the dist cap and see if its anywhere near #1 or 180 out, if so turn it again and use that as #1 for the plug wires. If the dist has been turned that can throw it off a bit too.
    Its easy to goof the wires.

    Dont forget the fuel filters.

    Ds

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    Senior Member Oldmech's Avatar
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    Quote Originally Posted by Down South View Post
    New wires are a good ideal. You just have a lot of Gremlins to chase down before you are done.

    Check to see if the distributor wire is plugs in good, and clean. A bit of dielectric grease wouldn't hurt.
    Now check to see if the distributor is plugged in good and clean. One is a power wire from the harness the other is from the cap to body of dist.

    If it doesn't fire up. Turn it till the timing marks line up, pop the dist cap and see if its anywhere near #1 or 180 out, if so turn it again and use that as #1 for the plug wires. If the dist has been turned that can throw it off a bit too.
    Its easy to goof the wires.

    Dont forget the fuel filters.

    Ds

    Good advise there. I have also found many distributors that were put in with the drive gear off a tooth or three, many times the person will just find TDC for number one cylinder and plop the wires on from where the rotor is pointing. It works perfectly fine but can seriously mess you up if you try to put the wires on correctly.
    Take number one plug out. Unplug the wires from your dist cap, put a finger over the spark plug hole and have someone bump the starter gently, dont turn it over, just keep bumping it until you feel or hear the HISS of pressure leak past your finger. Now take a light and look down at the harmonic balancer. Gently bump the engine again until the line in the balancer is lined up with the timing tab. THEN pop your cap off and see where your rotor is pointing. THAT will be where you want the number one wire to go. The cylinders on the drivers side starting at the front are 1,3,5, and 7. On the pass side of the truck, the cylinders from front to back are 2, 4, 6, and 8.
    You may have also moved the distributor itself when putting the wires on??? If so it will need to be timed with a timing light again, but you can usually get it close by ear. Unless you have done this often then make sure to get it timed correctly with a light soon!
    FYI.. everything that bolts to the outside of a 350 will bolt onto a 305, 327, 307, etc etc.. That was one of the reasons Chevrolet was so great, parts were cheap and easy to get.. For most of my life you could pull a small block out of... anything.. and make it work in..... anything! I have seen 80's trucks with everything from 283's to 400's in them. Also, the casting number for the block is on the drivers side rear cast into the engine block where the bell housing bolts up. a number like 3970010 is a general casting number for a 350.. 14010201 is a 305.. there are quite a few numbers, so once you dfind it you can look it up to see what you have, or post it and one of us will look it up for you.

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    And good point if something was jumping that would tell ya.

    DS

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    Senior Member zombie1969's Avatar
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    A 350 will have the timing tab off too the side and a 305 will have it at the 12 oclock position . The timing covers dont interchange because the 350 has a larger balancer . Good luck
    Sent using Boost mobile 4g htc evo.

  6. #6
    Senior Member Oldmech's Avatar
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    Quote Originally Posted by zombie1969 View Post
    A 350 will have the timing tab off too the side and a 305 will have it at the 12 oclock position . The timing covers dont interchange because the 350 has a larger balancer . Good luck
    Yep.. BUT.. you can put the 305 balancer and timing cover on the 350 or vice versa. you can even slap the 305 balancer on without changing the timing cover on the 350, and that opens a whole new can of worms when trying to time an engine.. fortunately it doesnt happen a lot, and as stated you can usually tell because of the different diameter. I have in the past dealt with many engine transplants where the 400 balancer and flywheel were bolted to a 350 and then the owner just couldnt figure out why it vibrated SO badly..

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    Forum Moderator Boudin's Avatar
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    It may be best here to just pull the distributor and bump it until you find TDC on the #1 cylinder and reinstall the distributor with the rotor pointing at the #1 cylinder. Sounds like you have the firing order correct and starting with the #1 cylinder, blug the wires in according to the firing order. This should get you close enough without a timing light and should require only moderate turning of the distributor to get it running right.

    It sounds like you are doing things correctly, but with so many places to make a simple error....it may be best to start from scratch so to speak. You might want to check for the plug wires to be correctly installed by simply checking the continuity of the wires with a multimeter. This way, you make sure they are conducting spark.

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    first it is normal for a replacement set to be a little longer than oem, i like it!....you have a running truck before you started making wires...i'm guessing there is a problem with them...start with the coil wire....if the dist was never pulled no need to mess with it
    4 wheels move the body
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    Forum Moderator Boudin's Avatar
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    I thought he had pulled the distributor. He's right....no need to pull it at this point unless you have pulled it during your repair process. If you have pulled it....you could be a few teeth off or 180 degrees out.

    I'm thinking the problem has to do with your wires, but I do know that mine will still run even though multiple wires are disconnected. I would check them all as see if there is a problem with their conductivity.

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    Finally fixed it. I misunderstood the instructions for finding TDC. After the compression stroke blew air out #1 spark plug hole I assumed that was TDC and plugged in my wires. It was **** and some contorting with a little hand mirror but I found my timing markers and TDC marker and advanced the pulley almost 180 degrees. THis time the rotor pointed at the opposite plug. I skipped the step that said to continue forward after compression stroke to find TDC. My bad. Fired right up once I moved all my plugs across the distributor.

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