Roger Posted April 14, 2011 Report Share Posted April 14, 2011 It has the L16 and weber carb. It was dieseling when I got it and I checked the timing. 2 degreees off--I corrected it. The idle speed screw I turned all the way out and still I think it idles too fast. No tach. Can't lower idle speed cause the screw is all the way out now. Could it be the carb? Quote Link to comment
jefe de jefes Posted April 14, 2011 Report Share Posted April 14, 2011 Is your choke opened up all the way? Quote Link to comment
banzai510(hainz) Posted April 14, 2011 Report Share Posted April 14, 2011 If u have a open chamber A87 or a U67 head this is common. put timming to 7 to 10 and see if this lowers the RPM Quote Link to comment
MicroMachinery Posted April 14, 2011 Report Share Posted April 14, 2011 Clutch kill: When you're ready to shut it off, put it in First with your left foot on the Clutch pedal and right foot on the Brake pedal. As you turn the ignition off, quickly remove your left foot from the Clutch pedal. The engine will not be able to run on with the transmission in gear and the truck not able to move(foot on brake, just in case). At first, it took a little while for me to get used to this, but now I do it automatically without thinking. Quote Link to comment
izzo Posted April 14, 2011 Report Share Posted April 14, 2011 Clutch kill. ^^ lol, it works Past few times i had this issue, i just double checked timing with timing light. And re-adjusted the carb. Cured it... (idle speed, and air/fuel mixture) Quote Link to comment
Roger Posted April 14, 2011 Author Report Share Posted April 14, 2011 choke plate is wide open. Timing is 10 degrees, was 7 or 8. Diesels more now. Don't know what head. It is a stock 1971. Quote Link to comment
izzo Posted April 14, 2011 Report Share Posted April 14, 2011 choke plate is wide open. Timing is 10 degrees, was 7 or 8. Diesels more now. Don't know what head. It is a stock 1971. Guessing A87 open chamber maybe? Look below #1 spark plug on head, should be a casting number there. grab a rag to wipe the head off if its dirty Quote Link to comment
Roger Posted April 14, 2011 Author Report Share Posted April 14, 2011 Maybe run a very low idle? Quote Link to comment
izzo Posted April 14, 2011 Report Share Posted April 14, 2011 dunno, any idea what its currently idling at? Quote Link to comment
Rob W. Posted April 14, 2011 Report Share Posted April 14, 2011 If the idle is already adjusted to it's lowest your idle jet could be too large which would make it impossible to slow the motor. Or as mentiones try leaning out the fuel air mixture a bit. What is the gas mileage like does it suck? Could be the carb is too rich. Quote Link to comment
banzai510(hainz) Posted April 14, 2011 Report Share Posted April 14, 2011 later model Datsuns have a anti desieling selinoid on the Hitachi carb. so when you shut the key off it plugges the idle jet.This is common with open chamber heads that cam to the USAand later years for emmisions. Since then most people buy Weber DGVs and 95% of them dont have the Weber DGV with the selinoid. closed chamber heads tend not to do this My 521 does it everyday. its a L18 with a U67 head. And when I had a aniti desieling selinoid on my other DGV I had it would still desiel on very hot days Quote Link to comment
Arun Posted April 14, 2011 Report Share Posted April 14, 2011 I would check the carb for a air leak Quote Link to comment
Arun Posted April 14, 2011 Report Share Posted April 14, 2011 Spray some carb cleaner around the base of the carb to see if it sucking air Quote Link to comment
datzenmike Posted April 14, 2011 Report Share Posted April 14, 2011 It has the L16 and weber carb. It was dieseling when I got it and I checked the timing. 2 degreees off--I corrected it. The idle speed screw I turned all the way out and still I think it idles too fast. No tach. Can't lower idle speed cause the screw is all the way out now. Could it be the carb? Check that the linkage is adjusted with some slack in it so the throttle can return to it's rest position. Quote Link to comment
wayno Posted April 15, 2011 Report Share Posted April 15, 2011 Hey Roger, you have a stock L16 with a weber on it, correct? Didn't the 1971 L16 have the 210 head on it, look just under the #1 sparkplug as mentioned in an earlier post right where the head rests on the block. If it doesn't say 210, it will be something like U67, or A87. I have a L20b with the W53 head Roger, I have dual SUs, and it has always dieseled, get used to it, the truck is so happy to have a new home that it just wants to keep going, and going like the energizer bunny.:lol: As mentioned before, just put it in gear and turn the key off and let out the clutch at the same time, before you know it, you will be doing it automaticly without even thinking about it. Quote Link to comment
Roger Posted April 15, 2011 Author Report Share Posted April 15, 2011 Right you are Wayno. It is a 210. Woo hoo? Truck wants to keep running because it likes its new home. LOL Got to deal with that weber. I bet it wouldn't do it with a Stock carb. Like I say, I got this truck second hand and do not know the details of the weber carb. Don't know anything about it. It sounds like an air issue of needs jetting. Is there a wever web site where I can buy those jets? I'll spary the carb w/cleaner and check for excess air. Quote Link to comment
banzai510(hainz) Posted April 15, 2011 Report Share Posted April 15, 2011 dont buy Arco gas. try another Gas company in case this might be suspect I have never had a 210 head desiel. I wont know if you feel good about doing this but ai get the motor going really good and pour a lilttle stream of water in the carb to hopefull clean out(steamclean the valves and pistons) Quote Link to comment
datzenmike Posted April 15, 2011 Report Share Posted April 15, 2011 Check that the linkage is adjusted with some slack in it so the throttle can return to it's rest position. Did you check this???? If it is it's an easy fix!!!!!!! It could have the wrong jets also. The head carbons up and it detonates. Check your plugs... if they are dry and black with carbon it could be the mixture. Quote Link to comment
Roger Posted April 16, 2011 Author Report Share Posted April 16, 2011 Good points. Wayno, we saw all that carbon in your head. I hear automatic transmission fluid can be used in place of water. Put a syphon straw in it and dhook it up to the intake--rev engine. I will investegate the spark plugs first. Water is a good idea as it is cheap. A bit wont hurt. Quote Link to comment
wayno Posted April 16, 2011 Report Share Posted April 16, 2011 Fact is Roger, my 521 has dieseled since the day I bought it and it has not effected it in any way that I know of, it did not wear it out, did not cause it to use more oil, it did not rob me of any power, in the past I have let it diesel to see how long it would, I beleave it almost made it to a minute, but it made all these unnatuaral knocking noises, so I didn't do that anymore. I wouldn't worry about it to much, just let out the clutch and turn the key off at the same time while it's in gear. I have heard of pouring stuff down the carb for somekind of end result, and it may just work, but if it was that reliable of a techniquie, you would know about it as a comman practice, like your neighbor would say something like, I have a fluid injection appointment next thursday to clean out the engine, not one person I know has ever said anything like that. As I said, it may work but I won't be doing it anytime soon, so far that buildup has not effected my engine other than to beat the shit out of the top of my pistons, and I did not know it did, till I pulled the engine apart. Be careful, I can imagine lots of things that could go wrong, like thermal lock. Quote Link to comment
datzenmike Posted April 16, 2011 Report Share Posted April 16, 2011 Alcohol will eat carbon. Windshield washer solution should work perfectly for this. Run a hose over to the carb and clip in place. Get the motor nice and hot out on the highway and floor it in third gear and hit the wash button. You'll notice a drop in power because much of the combustion heat is removed and not available to heat and expand the air and push down on the pistons. The carbon cools and shrinks suddenly and begins to crack and flake off. You will likely have to drive along to warm up the interior of the combustion chamber to repeat. I would try 3-5 second squirts and adjust as necessary. Many people have had leaky blown head gaskets, me included, and can attest to the cleaning effects of small amounts of coolant getting into the combustion chamber. Most drivers today have EFI and carbon isn't a problem. If they were convinced of it they would simply run and get a can of 'engine cleaner'. Carbon is more of a problem in carb engines. A friend showed me this trick back in the 60s. He had a 283 4bbl chevy. We opened the headers and revved it up while pouring a coke bottle of water down the open carb. A huge cloud of steam blew out the back and when we moved the car there was black shit all over the ground. He said the trick was the engine should be good and hot. Cost? about $0.25 for a Coke and some tap water. Quote Link to comment
Roger Posted May 11, 2011 Author Report Share Posted May 11, 2011 The dieseling was fixed 521 on da highway for about 500 miles. I think it got carboned up from lots of short, slow trips. I just blew the carbom out by driving the speed limit on the interstate. Quote Link to comment
wayno Posted May 12, 2011 Report Share Posted May 12, 2011 You must have some really slow speed limits on the interstates back east, I didn't know a stock 521 would do the speed limit.:lol: :lol: :lol: Quote Link to comment
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