Rebuilt 318 Refuses to Start

Small Block Mopar Engine

  1. 95dakotadude

    95dakotadude Well-Known Member

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    I have recently rebuilt my 318 after it spun a bearing. It is a highly modified engine meant for street/strip use.

    It will not start. We have spark, compression and fuel to the carburetor. It cranks and cranks but no start. Once in a while it will cough, but it's intermittent. I have put the long mark on the harmonic balancer to TDC and verified that the piston is actually at TDC on this point with a screwdriver and with the valve-cover off looking at the rocker arms. I've tried starting it from TDC with no luck. I've tried starting it ~8degrees advanced and retarded to no luck. We've always rotated the distributor all the way during these times to no avail. I am running a full MSD ignition system with a Holley 650 double pumper carb with 5.5lbs of fuel pressure to the rail.

    We are unsure if gas is actually getting into the cylinders though. It's going through the carburetor because I can see the gas squirting in it, but when I pull the plugs, they're dry. However, when I pull the carburetor which is sometimes full of gas from pumping it, the intake will have a little bit of gas in it. Sidenote: The carburetor is a newly rebuilt piece with less than 600miles on it.

    It still refuses to start and I've been working on it for like 3 days just on this stupid timing aspect. Does anybody have any ideas?
     
  2. 318willrun

    318willrun Stomper 4x4... we kept energizer in business

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    I'll just say, if you have air/fuel mixture, compression, and spark, it will run IF it's in time, and that included firing order. Start here......
     
  3. 95dakotadude

    95dakotadude Well-Known Member

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    Then it must be out of time still. But I'm lost. We've done everything that I know of and that I see online and I still can't get it right. Firing order is correct. 1 8 4 3 6 5 7 2 in clockwise order.
     
  4. DesertRat

    DesertRat FABO Gold Member FABO Gold Member

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    Information, the rotor rotates clockwise, check plug wires. I started mine for cam break-in at 34 degrees advanced and it fired on the first spin.
    That leaves fuel, check fuel level in float bowls. If all is good, all will be good. Good luck!
     
  5. circlepilot

    circlepilot FABO Gold Member FABO Gold Member

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    What 318willrun said..."timing"...I hope you got the timing marks on the cam and crank lined up. If all is right, it should go.
     
  6. 318willrun

    318willrun Stomper 4x4... we kept energizer in business

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    Why don't you try to pull the dizzy up an inch and rotate the shaft 180*
     
  7. 95dakotadude

    95dakotadude Well-Known Member

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    I don't have timing tape to go off of to make it anything that big advanced. All I have is the 5 above and below TDC from the timing cover. Unless there's another way you know about? I installed the timing chain dot to dot and spun it by hand once to ensure they'd still match up. I've also pulled the dizzy up and rotated it 180 multiple times. I have like 15 hours in on trying to time this thing lol
     
  8. 73Swinger18

    73Swinger18 ✱ⓈⓌⒾⓃⒼⒺⓇ

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    Firing Order.jpg
    Try throwing a match down the carb when cranking it :rolleyes:
     
  9. DesertRat

    DesertRat FABO Gold Member FABO Gold Member

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    Then you need to look at fuel, if you are convinced it is getting spark.
     
  10. 73Swinger18

    73Swinger18 ✱ⓈⓌⒾⓃⒼⒺⓇ

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    Have you verified your transition slots and idle mixture screws? Are you running a choke?
     
  11. memike

    memike Super Moderator Staff Member FABO Gold Member

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    I had a problem starting a new engine , all I had to do is put a tea spoon full of oil in each cylinder, simple I know, but it has happened to me a couple times, once on a 289 and not long ago on a 360.
     
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    • 95dakotadude

      95dakotadude Well-Known Member

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      I know it's getting spark. Swinger, I don't know much about carbs so I don't know what a transition slot is. Idle mixture I'm not sure what it's set at. I had the same carb and everything on the same engine previously before I built it and it ran fine; haven't changed a thing since then so I don't know why it wouldn't work now. I'm not running a choke but we have tried closing the butterfly valve to allow more gas etc.
       
    • 95dakotadude

      95dakotadude Well-Known Member

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      I had the same carb and everything on the same engine previously before I put new bearings in it is what I meant.
       
    • 318willrun

      318willrun Stomper 4x4... we kept energizer in business

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      I still think timing/spark related. If the carb ran good before, then to me it's not suspect. Something with the MSD....??????
       
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      • nm9stheham

        nm9stheham Well-Known Member

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        Boy this sounds frustrating for you.

        Hold the phone on the good spark....... That depends on how you are testing for spark. If you are pulling a plug and watching for spark across the plug gap in open air, that is a 100% invalid test. It takes a TON more spark voltage to jump a spark plug gap in a compressed fuel/air mixture than in open air.

        The way to test for spark is to remove a plug wire from the plug and set the bare metal end of the wire 3/8" from metal, like a fender or valve cover. The spark ought to be able to jump that large gap with a good blue spark.

        BTW, what cranking compression readings are you getting?

        Any way there could be a huge air leak in the intake manifold area, like under the carb or via a open PCV hose?

        How old is the fuel? A teaspoon of fresh fuel down the primary throats should make it fire off for a second or so and eliminate the carb and old fuel as an issue. But it sounds like the pumping has done that if the fuel is fresh.
         
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        • 73Swinger18

          73Swinger18 ✱ⓈⓌⒾⓃⒼⒺⓇ

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          The transition slot is where the carb transitions off the idle circuit. It should be square, or close to it. Too much exposed and you could be running rich and will cause other issues. I'd try setting your mixture screws 1.5 turns out from lightly seated. All the choke does is restrict air from entering the carb to make it run richer and aid in cold starts. It also sets your fast idle cam which maintains RPM at a higher setting while warming up. But if it all ran before, not sure if that's your problem. Would be worth looking at though. Is the MSD system a new install or previously verified good?
          slot.jpg
           
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          • jimjimjimmy

            jimjimjimmy lobsterman FABO Gold Member

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            you need to pour at least a half a cup of gas down the carb for a new engine to even think to start a few pumps wont do .
             
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            • 95dakotadude

              95dakotadude Well-Known Member

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              nm9s, to test spark I did the typical pull the plug out and touch it to a piece of metal and check for spark. I'll try what you said tonight when my dad gets back from work. The fuel is 93 octane and is roughly 4-5 months old. However, I did put a fresh 2 gallons in the tank (not sure how much is actually in the tank, no gas gauge) and we've tried more starting fluid than I care to admit just to try to hear the engine cough. The MSD ignition stuff all worked before and is all brand new. I just build the entire car not too long ago and it spun a bearing at 570 miles because of a stupid mistake I made while installing the engine. The only thing different from then is the new bearings. I don't have compression readings because I don't have the tool, but I know it's got good compression on #1 at least because when I spun the motor to find TDC on the compression stroke, it lets out a strong shot of air, loud enough to where you can hear the air in the cabin.
               
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              • TrailBeast

                TrailBeast Slightly Twisted Member

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                Have you checked the cranking vacuum?
                If the plugs are dry fuel may not be being pulled in.
                Even if the carb is ALL wrong you should still have an intermittent start and die if everything else is close.
                 
              • 73Swinger18

                73Swinger18 ✱ⓈⓌⒾⓃⒼⒺⓇ

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                It's a good idea to have a fire extinguisher around on the first start too. What nm9 said about the air leak happened to me before. In a rush, I left one of my vacuum ports open on the bottom of the carb and wondered why the engine wasn't starting all of a sudden.
                 
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                • jimjimjimmy

                  jimjimjimmy lobsterman FABO Gold Member

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                  dude if you were using starting fluid read post 11 and do it .
                   
                • 95dakotadude

                  95dakotadude Well-Known Member

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                  I will be trying all of these tonight when I go out with my Dad. He's been involved and I'd like to wait for him. What has us the most confused is why the spark plugs are completely dry even though the carb is filling up with gas. After reading post #17, I just ran out to the garage and made sure the carb had gas, gave it 3 pumps and it coughed for a second, and with every crank it shot out a mist of gas, is this normal? We have been gunshy on the gas since the first day where we think we flooded the crap out of it. I will try all of these things tonight. Here's how I intend to start:

                  1. Find TDC #1 on compression stroke.
                  2. Set the Harmonic balancer to 8 deg adv. - I heard this is what sbm like to be at for starting, correct me if I'm wrong. Or should I try to start it at TDC first?

                  3. Put the spark plug back in
                  4. Put the plugs on the dizzy
                  5. Put at least half a cup of gas in her
                  6. Crank

                  If this doesn't work, I'm starting with the things listed here.

                  As another question that I have seen different answers to online: the timing cover has 5 degrees before and after TDC, with a mark for TDC. 8 marks underneathe TDC (towards the bottom of the engine) would indicate ADVANCE, right? And the 5 above the TDC mark (towards the hood) would be 8 degrees RETARDED. Or do I have those flipped?
                   
                • nm9stheham

                  nm9stheham Well-Known Member

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                  I'd not use a 1/2 cup of fuel..... too much and it will wash the oil off of the cylinderwalls. At this point, the suggestion of a bit of oil in each cylinders seems wise; the pumping and fuel in the intake means you may have washed down the cylinder walls already.

                  4 to 5 months old fuel is OLD with the new fuels. We have had starting issues before with fuel of that age, and put in some fresh and ZOOOM! It is several factors that effect fuel volitility and it sounds like you may have a large cam and you are going to need all the fuel volitility and compression you can get to fire it off. Putting in 2 fresh gallons won't do it.

                  And if you did not clean the carb out 100% of fuel when you pulled it, including pumping all of the fuel out of the accelerator pump system, then odds are darned good that some of the ethanol has separated and absorbed water and formed gum. We had this exact thing happen in the last year and it had gummed up the check valve just below the accelerator nozzle in just under 3 months time. It had to be cleaned out. (And then I unknowingly dropped the check valve down the carb.... oops, that's another adventure LOL)

                  And on the starting fluid.... that is hard on the cylinder wall oil layer and I never use it anymore unless on a lawnmower. But you think it would have at least fired... which goes back to the spark or a big vacuum leak.
                   
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                  • 73Swinger18

                    73Swinger18 ✱ⓈⓌⒾⓃⒼⒺⓇ

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                    When I saw that post of yours, I triple check for that valve now when I do anything with the nozzle!
                     
                  • 95dakotadude

                    95dakotadude Well-Known Member

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                    I think I cleared out the carb when I pulled it, but I can't say for sure. I'll take a gander at it today. I suppose it won't hurt to throw some oil down in the cylinders as well. Should I attempt to start it at TDC on the harmonic balancer, or do I want to advance it before I try starting it? Also, is it normal for the gas mist to come out of the carb while cranking?
                     
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