318 2bbl won't idle without choke

Small Block Mopar Engine

  1. toolmanmike

    toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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    It's shakin' like a dog poopin' peach seeds! Yes it sure does have a hiss to it. I would just cover the top with my hand and if it smooth's out you know it is running lean and/or has a vacuum leak.
     
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    • AJ/FormS

      AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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      The reason that I mentioned that you can run the engine with the top off, and the horseshoe shaped float-pin retainer pressed down,
      is so you can see what the power-piston is doing.
      If the manifold vacuum is too low, the piston comes up, and if there is enough signal in the booster, then it will begin dribbling.
      My first response to that is to just grab the distributor and give it a bunch of advance,until it runs as smooth as it gets. You cannot hurt the engine by doing this, even if it gets up to 25 or 30degrees. Don't even put the light on it at this point. The increased timing will increase the manifold vacuum, and suck the power piston down;(BTW, there is no gasket under the power piston. If you put one there, the needles will go up, and make the entire system rich, and/or, the transition will be wrong from Idle to Part Throttle :: Ok, let me rephrase that; I have never seen a gasket there (just because I have never seen one there, doesn't mean that a model might have been designed to have one, I've just never seen one), and there is no point to put one there, and IIRC, the vacuum port comes in on the side of the bottom down there, and would be covered by a gasket, if you put one in there. If the port gets covered, guess what; Hyup, the power piston stays full rich.
      Now, with the extra timing, you can idle it down, restore the transfer slot sync, and go find why it sounds like it has a horrendous air leak.
      And finally, when you get that figured out, you have to put the timing back.

      Furthermore, put a vacuum gauge on it.
      It will tell you about the low vacuum, which could be caused by, in order of likelihood;
      1) an air leak; base gasket or intake to head, power brake booster, broken PCV valve or it's hose, or even the vacuum take-off tree.
      2) retarded ignition timing
      3) retarded cam timing
      4) intake valves not closing
      5) plugged muffler
      6) faulty exhaust valve(s)
       
      Last edited: Sep 19, 2020
    • pishta

      pishta I know I'm right....

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      Throw another carb on it! Im sure there are at least 5 on this board that have gone from a 2 to a 4bbl and are just waiting for a reason to touch that 2bb again. I got 2 2bbl intakes for a LA and I don't even know where I got them! sorry, no 2bbls unless you want a completely worn out Nikki 2bbl from a Mazda. I suggested a vacuum gauge a few posts ago. If its fluttering crazily, you may have a burned valve, that will throw a wrench into any carb tuning your trying..... remove the valve covers, and take the rockers off, check your valve heights. Remove the carb and put a shop vac in the tailpipe. Listen for hissing in the intake. Just runs so rough it looks like a vacuum leak. pinch all vacuum hoses or remove them and plug them. process of elimination.
       
    • Tylinol

      Tylinol Active Member

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      Here we are running with a clear carb top I made, and a makeshift "choke". Vacuum gauge with the "choke" read about 5, and yesterday read about 15 when we were running it with the choke off.

      I'm beginning to suspect the timing. My timing gun broke, but looking at it statically the points haven't even started to open until well after TDC - at least 10* if not 15 or more. MY research has alerted me to the nylon timing gear these engines used, and since I'm sure mine is original I'm inclined to replace it and the harmonic balancer (and the water pump while I'm there) before going much further.
       
    • pishta

      pishta I know I'm right....

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      5! That sucks..barely! 15 is better, steady 18 is great. 5 must be with the choke on the fast idle step but still low. find TDC with a piston stop (or a drumstick jammed in a plug hole: run it up slowly with the crank bolt, mark damper at TDC tab when it just touches, reverse the crank 300 degrees and mark damper @ TDC again when it just touches again and bisect the 2 marks exactly, there is your real TDC on damper, probably not far off the original if at all) Run new mark to TDC and then youll have to check cam dot. Your points should just be opening (@10 BTDC, 'limp home' timing) or right before. If you have a dial indicator you should be able to find cam timing with a cam card and a degree wheel looking for intake starting to open at about 21 degrees BTDC
       
    • AJ/FormS

      AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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      post #15
      well, at least the power-piston is staying down. You know, with your cover,you can raise the needles manually, and see if the engine responds favorably.
      I still hear what I think is a huge vacuum leak. If true, then raising the needles manually will both speed the engine up AND smooth it out.
      On the list I made earlier,post 52, I forgot to include wrong base gasket, in the sources for air leaks, I will go edit it right now. Ok, no; it's there.
      For that 2-bbl there are a couple of different base gaskets available
       
      Last edited: Sep 20, 2020
    • AJ/FormS

      AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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      I think you're chasing ghosts on the nylon gear, mine is circa 1973. If it runs, then the nylon timing gear is on there and in no way broken, they do not shed individual teeth. They are nylon/not plastic. If you pull the D out to look, you will just add more confusion when trying to re-install it.

      I think I might mentioned it a couple of times already, to just tug on the V-can and put some advance into that thing; irregardless of the number; just pull! We can chase the balancer later. At 2000 rpm that engine will like over 40* of advance in N/P, maybe even as much as 56*.
      At 650, it's gonna like maybe 25/30; you cannot hurt it; Just PULL!
      For testing purposes, open up the points to not less than .022, (actual amount not important; I just want to see the condenser is working, and eliminate a miss due to a closed point on one cylinder caused by a worn-out top bushing or bent shaft), then, pull on the Vcan with the engine running, until it smooths out. Keep advancing until it slows down, then back up some. This is just a test. If it smooths out, then you know we're on the right track. If the sucking sound simultaneously also goes away, so much the better. Pull!

      Unless you physically broke your timing-light it may not be as broke as you think. If the plugs get shorted out by a rich mixture, the hi-tension voltage leaks to ground, and your timing light will not register a spark. The proof is to put your clamp on another wire, and seeing a strobe on that one. Then your light may be fine.
      Post edited several times; hit refresh
       
      Last edited: Sep 20, 2020
    • Tylinol

      Tylinol Active Member

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      I just tried giving it a ton of advance - it started slightly easier but not much. I ran a compression check and got 100-115psi on all cylinders, which should at least be ok enough to run.

      If I turn the crank back and forth at the harmonic balancer, there's about 10 degrees of slop between it and the distributor rotor. Maybe my timing chain has stretched?
       
    • jay27

      jay27 Well-Known Member

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      I am just wondering , was it running fine before you did all the work ie , ignition wires , cap , rotor , plugs , points and carb rebuild or did it always run poorly. I dont remember if you mentioned this already.
       
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      • Tylinol

        Tylinol Active Member

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        It ran reasonably well before the second time I took the carb off. Started VERY easily. It had trouble idling at the correct speed (I had to bump it up to 1200 or so to keep it from stalling) and would die without ~30% choke though.

        Edit: Although I probably only put 5-10 miles on it like this. I've been reviving the car from 25 years of sitting by the PO
         
      • jay27

        jay27 Well-Known Member

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        There is either a blockage somewhere or its really lean , (could be from a blockage) or something is off somewhere. It is not the timing chain and albeit your vacuum seemed a little low that could simply be late timing or a vacuum leak. I know you probably heard this from other members but that is what it seems like in my opinion. I would look for another carb to at least compare to if possible.
         
      • Tylinol

        Tylinol Active Member

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        Well, a little update. Since I was planning on replacing the water pump anyway, I thought I might was well put a new timing chain on and investigate the old one to rule it out. Turns out that was the right call. Chunks of at least three teeth are missing, and the chain has enough slack to slap the timing cover (which makes an awful rattling sound I attributed to the water pump and hadn't noticed at all until last week when I put the exhaust on, it was open manifolds before that).

        So carb blockages aside, my valve timing is clearly whack. I also presumably have chunks of nylon floating around in my engine somewhere. Is this game over for this engine, or can I attempt to drop the pan and hopefully find the chunks sitting in the bottom? I'm not sure if the 318 has an extra oil pump screen and filter like my VW does.

        IMG_0699[1].JPG
         
      • Phreakish

        Phreakish Well-Known Member

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        Slap a timing set on it and then check compression. That will tell you if it's worth sealing the engine back up.
        The oil pick up has a screen, so that nylon likely hasn't gone any farther than the pickup - sub optimal situation, but the engine is likely serviceable even if you don't find those chunks.

        Personally, I'd still want to drop the pan. The amount of crud on there suggests the pan is full of all kinds of crud that would be best to remove. But dropping the pan in-car is not something I'd want to do, either.

        What's your intention with the car?
         
      • Tylinol

        Tylinol Active Member

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        Daily driver. I've been working on reviving it and trying to make it as reliable / robust as is reasonable. I would have loved to have it driving this fall (and feel like I was right on the cusp of it; I had everything sorted besides the carb tuning before this) but I'm not entirely against pulling the engine and rebuilding it in my garage over the winter either.
         
      • Phreakish

        Phreakish Well-Known Member

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        If that's the case, personally I'd pull it. For a DD, my personal expectations are pretty high. I would want a nice, clean, tight engine in a DD.
         
      • TT5.9mag

        TT5.9mag Two atmospheres are better than one

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        Glad you found something going on and it turns out @AJ/FormS was right on about your timing. It’s definitely hard to get a good tune on a carb with the cam timing all over the place. I also agree with @Phreakish that I would slap a timing set on it and run a compression/leak down test to see if it’s worth moving forward. I wouldn’t pull it just yet. But based on the amount of sludge in your pic, and the results of the compression test, I would at the very least drop the pan, clean it and the pick up screen before buttoning it all back up. And if I did get it running and was not planning on going through it, I would do more than a few oil changes in the first couple thousand miles.
         
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        • AJ/FormS

          AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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          IMO, that engine is done; the crud is evidence of blowby, a lot of blowby. As it is, I wouldn't spend another nickel on it.
           
        • dogbreath

          dogbreath Well-Known Member

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          8 burnt exhaust valves =low vacuum = shi##y idle
           
        • Nat

          Nat Well-Known Member

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          to find a good 360 and rebuild it if the 318 is toast . i've had a 318 that lost teeth on the gear that i rebuilt but the engine did not have the crud buildup yours does
           
        • pishta

          pishta I know I'm right....

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          Id take a power washer to that motor as it sits right now. Pull the pan and hose her down. New $16 timing set and roll the dice. as soon as you get it idling, dump a can of engine flush in there and let it idle for 15 minutes. That's some serious sludge.
           
        • TT5.9mag

          TT5.9mag Two atmospheres are better than one

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          I revived one that chewed all the teeth on the nylon gear and had sludge similar to that. That was 3 years ago. Still running.
           
        • AJ/FormS

          AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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          The thing is;
          all that sludge
          plus the broken and spit out umbrella seals
          are all in the oil-pick up ........... and the heat-cross-over is all coked up, and the rings are plumb wore out, with a huge taper at the top of the bore.And the lifters lost there crown decades ago. Crank end-play can probably be measured with a yard-stick, and the rods knock every morning.
          On another note;
          I had a 71 Demon, and when the chain jumped, the pistons in the stock engine, promptly kissed the valves.
           
        • TT5.9mag

          TT5.9mag Two atmospheres are better than one

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          Aj I don’t disagree with you at all. I’m just stating what I’ve done. I’m not recommending anything. But I hesitate to make any real suggestions because I can’t put my own eyes on this engine. Who knows it may last another 10 years with new chain and some valve seals. On the flip side it may last a week. But I would try because it leaves him in no worse situation than he is currently in.
           
        • AJ/FormS

          AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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          Sorry man I wasn't directing at you or I woulda hit the @TT5.9mag . My apology if your dander was raised. Same goes to @pishta, or anyone else who's toes I might have stepped on
          No post 72 was for the OP, because it had not yet been mentioned.

          But as always, thanks to all who who come at me gentle-like.
           
        • TT5.9mag

          TT5.9mag Two atmospheres are better than one

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          I didn’t take it that way. And trust me it takes way more than that to “raise my dander”. We’re just sharing info.
           
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