banzai510(hainz) Posted February 5, 2016 Report Share Posted February 5, 2016 well if carb is new, dist is tight I really dont know, beside ck the valve lash. Now if you opened up the new carb and fucked with it anything can change. but they really pretty simple. I had bad things like plug wires arching or spark plug electrod smashed before but most people catch these and we just dont mention it. reground the condensor or get a new one. inspect it closely Quote Link to comment
sanyantho Posted February 5, 2016 Author Report Share Posted February 5, 2016 well if carb is new, dist is tight I really dont know, beside ck the valve lash. Now if you opened up the new carb and fucked with it anything can change. but they really pretty simple. I had bad things like plug wires arching or spark plug electrod smashed before but most people cat these and we just dont mention it. reground the condensor or get a new one. inspect it closely Thanks Hainz, I did not mess with the carb. I will check the valve lash in a bit.I will pull out the plug and check those as well. I will diffidently check the condenser and replace. Quote Link to comment
datzenmike Posted February 5, 2016 Report Share Posted February 5, 2016 Hey Mike, I took the cover off the top of the carb to check and it was running dry. So I adjusted the float level, it running correct now. But that did not stop the backfiring out the carb. In fact, it seem to have gotten worst. Now while I am idling, and I push on the gas, it starts to backfire. Before it would only backfiring as I take off on first gear. I am going to check the valve lashes again, as you suggested. Anything else you can think off? Thanks so much for your help everybody! You should have pulled the main jet out while the cover was off to see if part blocked. The float was probably out of whack from all the backfires. Check valve lash. A tight intake won't close properly. Also an intake valve may be burned/cracked and not sealing. Quote Link to comment
sanyantho Posted February 6, 2016 Author Report Share Posted February 6, 2016 You should have pulled the main jet out while the cover was off to see if part blocked. The float was probably out of whack from all the backfires. Check valve lash. A tight intake won't close properly. Also an intake valve may be burned/cracked and not sealing. So I was checking the valve lash and found that the valve spring was not set correct or loose on the first intake valve. This is the valve that I had to shave off the adjusting bolt to give more pay to get the clearness. When I put the post, shaved adjustment bolt, and spring back together, I did not set the spring correct because it had way more pay than the other valve springs. Now that I set the spring in correctly and tighten it the best I can, the truck runs like a beast! No more backfiring, seem to have more power also! Does anybody know where I can get the valve spring? I know I going to need to replace it, because it is so weak compare to the other valve springs. Thanks you Mike and Hainz! Quote Link to comment
sanyantho Posted February 6, 2016 Author Report Share Posted February 6, 2016 The number one spark plug on the right compared to the rest on the left. Quote Link to comment
datzenmike Posted February 6, 2016 Report Share Posted February 6, 2016 The little clip on spring? We call them the mouse trap. Not essential for closing the valve but helps position and hold the rocker on the adjustment post Check valve lash. A tight intake won't close properly. The intake clearance was likely too tight and the valve not sealing tight. When the cylinder fires the explosion got past the valve seat and ignited the intake 1 Quote Link to comment
sanyantho Posted February 6, 2016 Author Report Share Posted February 6, 2016 Where can I buy the little mouse trap. Going to need it. The mouse trap was not installed correctly not the valve spring. I didn't know what to call it.Thanks Quote Link to comment
KoHeartsGPA Posted February 6, 2016 Report Share Posted February 6, 2016 The number one spark plug on the right compared to the rest on the left. Check for leaks in the intake manifold gasket where it bolts into head for #1 cylinder....when it's running spray carburetor cleaner in that area and listen for changes in idle....try not to do it when engine is very hot. 1 Quote Link to comment
datzenmike Posted February 6, 2016 Report Share Posted February 6, 2016 Where can I buy the little mouse trap. Going to need it. The mouse trap was not installed correctly not the valve spring. I didn't know what to call it.Thanks What's wrong with it? Quote Link to comment
sanyantho Posted February 6, 2016 Author Report Share Posted February 6, 2016 What's wrong with it? Its very weak, I can move it easy with my finger tip. While the other mouse trap on the rest of the valves are strong and stiff. Quote Link to comment
sanyantho Posted February 6, 2016 Author Report Share Posted February 6, 2016 Check for leaks in the intake manifold gasket where it bolts into head for #1 cylinder....when it's running spray carburetor cleaner in that area and listen for changes in idle....try not to do it when engine is very hot. I will give it a try tomorrow. Thanks 1 Quote Link to comment
KoHeartsGPA Posted February 6, 2016 Report Share Posted February 6, 2016 Check out your local junkyard for that spring, they might not even charge you for it... 1 Quote Link to comment
datzenmike Posted February 6, 2016 Report Share Posted February 6, 2016 Any L series engine L16/18/L20B/240/260/280z or zx or the 810/Maxima will have them. 1 Quote Link to comment
KoHeartsGPA Posted February 6, 2016 Report Share Posted February 6, 2016 Good to know, Mike, I wasn't sure they have the same part, I'm very new to dattos, learning as I go :) Quote Link to comment
sanyantho Posted February 6, 2016 Author Report Share Posted February 6, 2016 Thanks guys, I will look for them in my local junk yard. :thumbup: 1 Quote Link to comment
banzai510(hainz) Posted February 6, 2016 Report Share Posted February 6, 2016 I have tons of those Rat trap springs, see if anybody has some locally. glad its working out OK. You will need that head redone soon as the valve is sinking. Usually its the exhaust valve that does this. spark plugs are mostl likely fine. cant really do much with it anyways. Buy a timming chain tool from amazon. datsun L series timming wedge. Quote Link to comment
sanyantho Posted February 6, 2016 Author Report Share Posted February 6, 2016 I have tons of those Rat trap springs, see if anybody has some locally. glad its working out OK. You will need that head redone soon as the valve is sinking. Usually its the exhaust valve that does this. spark plugs are mostl likely fine. cant really do much with it anyways. Buy a timming chain tool from amazon. datsun L series timming wedge. My valve is already sinking. But mines is an intake valve. Where do I take the head, to get them redone? I will buy the timming wedge asap. Thanks Quote Link to comment
Doctor510 Posted February 6, 2016 Report Share Posted February 6, 2016 Brass seats or dropped seat Quote Link to comment
datzenmike Posted February 6, 2016 Report Share Posted February 6, 2016 My valve is already sinking. But mines is an intake valve. Where do I take the head, to get them redone? I will buy the timming wedge asap. Thanks Might be easier to just source a U67 head from any L20B. Larger intake ports and larger exhaust valves with square ports to match your L18 exhaust manifold. Quote Link to comment
sanyantho Posted February 7, 2016 Author Report Share Posted February 7, 2016 Might be easier to just source a U67 head from any L20B. Larger intake ports and larger exhaust valves with square ports to match your L18 exhaust manifold. From a local junkyard? 1 Quote Link to comment
sanyantho Posted February 7, 2016 Author Report Share Posted February 7, 2016 Brass seats or dropped seat Im not sure, mine is a a87 head. Quote Link to comment
banzai510(hainz) Posted February 7, 2016 Report Share Posted February 7, 2016 I had a later U67 head and the seats are the harder type but good Head shp needs to be found that does Datsun heads and can install seats well. I always have a extra Head that I can install and then research this at a more leasurely pace. not to give it to the wrong shop. They have to shave the head then install the seats recut them so the same lash pad can be installed ect. Quote Link to comment
sanyantho Posted February 10, 2016 Author Report Share Posted February 10, 2016 Hi All, I bought an u67 head from a member for $335 including shipping. Should I install right away or wait until the stock head(one currently running) goes completely dead? I already order the timing wedge tool from Amazon, as well ask the head gasket. I still looking to order the intake/exhaust gasket. Does anybody know where I can order that from? Thanks in advance! Quote Link to comment
KoHeartsGPA Posted February 10, 2016 Report Share Posted February 10, 2016 Don't fix what's not broken. 1 Quote Link to comment
Rick-rat Posted February 10, 2016 Report Share Posted February 10, 2016 Rock auto or Napa for gaskets, I would wait if it is running good 2 Quote Link to comment
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