Datsun/Nissan finatic Posted January 31, 2012 Report Share Posted January 31, 2012 I own a 78 620, seems i cant work out the kinks on my own. Did not run when i bought her but i knew the carb was clogged. I got her running was able to get her well enough to drive her. Just recently drained the coolant. Now shes not anything she was before. Im getting lots of fuel spray out of primary and secondary wont open with vacumn. secondary barrel is bone dry and she wont rev over 3000rpm. Not sure what to do. It now sounds like a popping two stroke out of primary barrel. so much fuel shoots out when attempt to rev her up. What did i do to my baby please anyone? Quote Link to comment
datzenmike Posted January 31, 2012 Report Share Posted January 31, 2012 Check the wires are going to the correct plugs. 1342 is the order. Inspect the condition of the wires, cap and rotor. Specially the cap and rotor. Probably not the prob but it costs nothing and is very easy to do. Check and set the valve lash. A little more work but a too tight valve will cause carb backfires and spitting. Do a compression check. Look for a low cylinder (possible damaged valve or valve seat) or two adjacent low cylinders. (gasket blown between them) Quote Link to comment
KC Phirus Posted January 31, 2012 Report Share Posted January 31, 2012 First off.Rebuild the carb, Can't hurt. 13$ rockauto.com. (620 is under nissan) Not trying to be a smartass... When you drained the coolant, did you put some back in it? Quote Link to comment
Datsun/Nissan finatic Posted January 31, 2012 Author Report Share Posted January 31, 2012 Check the wires are going to the correct plugs. 1342 is the order. Inspect the condition of the wires, cap and rotor. Specially the cap and rotor. Probably not the prob but it costs nothing and is very easy to do. Check and set the valve lash. A little more work but a too tight valve will cause carb backfires and spitting. Do a compression check. Look for a low cylinder (possible damaged valve or valve seat) or two adjacent low cylinders. (gasket blown between them) she ran fine and out of no where makes me lean towards gasket Quote Link to comment
Datsun/Nissan finatic Posted January 31, 2012 Author Report Share Posted January 31, 2012 timing is set to 12 btdc and i have two carbs swapped em and im getting the same thing it almost seems the carbs blowing rather then sucking when reving Quote Link to comment
KC Phirus Posted January 31, 2012 Report Share Posted January 31, 2012 she ran fine and out of no where makes me lean towards gasket Not sure what you mean by spraying fuel. Is it flooding the engine? Carburetor Or shooting the fuel/air back out of the carb? Sounds like a serious timing or valve issue. Ok nvm.... Check the plugs, have you messed with them? make sure they are in the right order. Center the timing and adjust it as necessary. Quote Link to comment
Datsun/Nissan finatic Posted January 31, 2012 Author Report Share Posted January 31, 2012 Not sure what you mean by spraying fuel. Is it flooding the engine? Carburetor Or shooting the fuel/air back out of the carb? Sounds like a serious timing or valve issue. the truck idles wonderful and ran well till the other day when i drained coolant and put fresh now when you pump the gas you litaraly see fuel vapor spraying out of primary and secondary is bone dry Quote Link to comment
datzenmike Posted January 31, 2012 Report Share Posted January 31, 2012 Have you done anything to it lately, anything at all? Borrow a compression tester for the night and see if it shows anything. Quote Link to comment
Datsun/Nissan finatic Posted January 31, 2012 Author Report Share Posted January 31, 2012 still have to do the compression check but thats it were talking head gasket rite? Quote Link to comment
KC Phirus Posted January 31, 2012 Report Share Posted January 31, 2012 the truck idles wonderful and ran well till the other day when i drained coolant and put fresh now when you pump the gas you litaraly see fuel vapor spraying out of primary and secondary is bone dry Secondary doesn't do anything unless you open it up. Idles or idled*? You sure you didn't do anything else? Yet again sounds like bad timing, Or something fucked up with your valves. Does the timing chain rattle/slap? Could be headgasket if it has busted between two cylinders and the exhaust from one is pushing through the intake valve of another. At least I think that makes sense. Quote Link to comment
Datsun/Nissan finatic Posted January 31, 2012 Author Report Share Posted January 31, 2012 Secondary doesn't do anything unless you open it up. Idles or idled*? You sure you didn't do anything else? Yet again sounds like bad timing, Or something fucked up with your valves. Does the timing chain rattle/slap? I do beleive the timing chain is strected or skipped a tooth because the only way to get 12 degrees the rotor is so far advanced that the vacumn diaphram on dist is hitting cant turn any more Quote Link to comment
KC Phirus Posted January 31, 2012 Report Share Posted January 31, 2012 I do beleive the timing chain is strected or skipped a tooth because the only way to get 12 degrees the rotor is so far advanced that the vacumn diaphram on dist is hitting cant turn any more winner winner chicken dinner Quote Link to comment
datzenmike Posted January 31, 2012 Report Share Posted January 31, 2012 I do beleive the timing chain is strected or skipped a tooth because the only way to get 12 degrees the rotor is so far advanced that the vacumn diaphram on dist is hitting cant turn any more The distributor is turned directly by the crankshaft so timing chain position or wear has nothing to do with it. Have you done anything to it lately, anything at all? So have you set the timing recently then??? Quote Link to comment
Datsun/Nissan finatic Posted January 31, 2012 Author Report Share Posted January 31, 2012 i have been able to use the truck all last summer with dist advance. parked for a year now this I guess im looking for an L20b short block any one in new york area Quote Link to comment
KC Phirus Posted January 31, 2012 Report Share Posted January 31, 2012 The distributor is turned directly by the crankshaft so timing chain position or wear has nothing to do with it. So have you set the timing recently then??? So if the timing chain has slipped and the valves are not time right that wouldn't cause the issue he's having?? ALSO could be a stuck intake valve. I got an idea right Cut down the search a bit Grab the pulley and turn the engine over with other hand over carb till you feel it pushing air. When it stops pushing air, pull the plugs and grab a flashlight and find out who's at TDC. Also pull the valve cover off and check for anything... abnormal. Quote Link to comment
Digi7al Trauma Posted January 31, 2012 Report Share Posted January 31, 2012 The distributor is turned directly by the crankshaft so timing chain position or wear has nothing to do with it. So have you set the timing recently then??? .... im with you mike... ...he said he parked it for a year.... im thinking points/rotor need to be cleaned.. at least... id replace em cuz they are cheap, check all wire connections/vac lines.... and MAKE SURE the spark plugs are correct.... theres no need to buy a new block... cuz honestly that has nooothing to do with any issue... if anything if would be a head/cam/valve issue... Quote Link to comment
Datsun/Nissan finatic Posted January 31, 2012 Author Report Share Posted January 31, 2012 sounds right about gasket one cylinder is spitting exuast into fuel side cause i swear you can hear it coming from carb sounds like a popping sound like two stroke and loud out of primary so i guess im tearing her down could use any help i can get like pictures or to do step by step thanmks Quote Link to comment
Digi7al Trauma Posted January 31, 2012 Report Share Posted January 31, 2012 sounds right about gasket one cylinder is spitting exuast into fuel side cause i swear you can hear it coming from carb sounds like a popping sound like two stroke and loud out of primary so i guess im tearing her down could use any help i can get like pictures or to do step by step thanmks what you just described is a backfire..... check your timing and your plugs wires, rotor, and cap... Quote Link to comment
Datsun/Nissan finatic Posted January 31, 2012 Author Report Share Posted January 31, 2012 i have went over everything i can possibly think of is there any possibility there is air pocket in coolant when i drained and now the tvv isint working right Quote Link to comment
Digi7al Trauma Posted January 31, 2012 Report Share Posted January 31, 2012 i have went over everything i can possibly think of is there any possibility there is air pocket in coolant when i drained and now the tvv isint working right what does an air bubble in the coolant have to do with the motor running fine? i dont mean to offend... but id honestly suggest you take it to someone with a solid mechanical knowledge... even if its a buddy.. 1 Quote Link to comment
Datsun/Nissan finatic Posted January 31, 2012 Author Report Share Posted January 31, 2012 plugs wires cap and rotor all checked. And the popping is constant bubbling but very loud like a dirt bike Quote Link to comment
KC Phirus Posted January 31, 2012 Report Share Posted January 31, 2012 So if the timing chain has slipped and the valves are not time right that wouldn't cause the issue he's having?? ALSO could be a stuck intake valve. I got an idea right Cut down the search a bit Grab the pulley and turn the engine over with other hand over carb till you feel it pushing air. When it stops pushing air, pull the plugs and grab a flashlight and find out who's at TDC. Also pull the valve cover off and check for anything... abnormal. Maybe try some of this? Jeez it's not time to teardown unless you really want to ollzz A valve not closing is highly possible. Head gasket would (possibly) include all/and/or loss of power, water in exhaust, oily plugs, oil in exhaust. Compression gauges start at like 13$. I think you need to calm down, drink a beer, and start from the TOP of the engine. Quote Link to comment
datzenmike Posted January 31, 2012 Report Share Posted January 31, 2012 So if the timing chain has slipped and the valves are not time right that wouldn't cause the issue he's having?? Think about it... The intake closes about 117 degrees before the plug fires and the exhaust opens about 126 degrees later. That would have to be one hell of a slipped chain to have either valve open when the plug fires. It simply wouldn't run in that condition. ...he said he parked it for a year.... im thinking points/rotor need to be cleaned.. at least... id replace em cuz they are cheap, check all wire connections/vac lines.... and MAKE SURE the spark plugs are correct.... theres no need to buy a new block... cuz honestly that has nooothing to do with any issue... if anything if would be a head/cam/valve issue... It's a '78 so won't have points. It is odd that the dizzy is advanced so much. Something is out there or has been out and put back wrong. Quote Link to comment
Datsun/Nissan finatic Posted January 31, 2012 Author Report Share Posted January 31, 2012 i only asked that because there is a thermal vacumn valve and i thought maybe it wasent working properly from air or maybe stuck thermostat, cause she ran great untill i did a coolant flush Quote Link to comment
Digi7al Trauma Posted January 31, 2012 Report Share Posted January 31, 2012 ....take it to a mechanic...... my last comment cuz now i feel like im being trolled .... i wonder if this is kazi? "It's a '78 so won't have points." so 78 didnt... but 79 did? Quote Link to comment
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