Jump to content

71 Datsun 521 running terrible


Recommended Posts

Hope you guys can help the new guy. LOL

Well bought this truck off a guy that didnt drive it for 3yrs. Would barely run. Took it home on trailer. Within 2 days had it running great! changed fluids gas, oil, anti freeze....etc. Put new fuel filter, new accel pump, dry rotted. Changed Alt & Reg. was not charging. now it is.

Drove this a few days without an issue then....... started missing out really bad. Almost didnt make it home. Tried new plugs. not that. Put on new fuel line. Nope not that. Changed out Carb for a new one. not much better. Put in new Points & gapped at .019. ran a little better. Still cuts out if you give it any gas. You gap the carbon on the flats of the shaft right? What gives? Any ideas? Does anyone know someone that could take a look for me. I live in Converse, IN. Thanks Troy

Link to comment
  • Replies 8
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

my guess would be that you dislodge some junk in the gas tank. Run a line from the fuel pump inlet(right on the pump) to a gas can.....if it runs great, it's the line from the tank, or the tank itself...or the filter if there's one between the tank and pump.

Link to comment
Put in new Points & gapped at .019. ran a little better. Still cuts out if you give it any gas. You gap the carbon on the flats of the shaft right?


When you say "carbon", are you talking about the rub block on the points? You should gap the points with the rub block on one of the high points (lobes) of the shaft. .019" should work.



Link to comment

Dang I was tired last night. Upon re-reading......


Make sure you accel pump in the carb is working. You should get a squirt down the throat when you actuate the throttle(not running).


Which carb is on it? Could also be the float level. If it's a Hitachi....check the screen at the fuel inlet to the carb.

Link to comment

OK got points correctly gapped. Starts right away, runs kinda rough. Accel pump is squirting in carb. Float seems fine gas to line level. Screen clean. Its a hitachi re-man carb. Brand new gas line with no blockage. Fuel pump is working. Here is the kicker guys. With choke pulled out it runs great. If you step on the gas it does not bog down or die. If choke in or off it will run rough but stay running that is till you step on the gas, this pretty much kills it. Is it possible I got a faulty carb??? The brass Slotted screw in the carb where the fuel comes out when you pump the acce pump by hand. My new carb does not have this???? My old one did!!! Do i need this for the carb to function right? Wow this thing is hard to dial in!!!!!

Thanks again, Troy

Edited by Tdatsun1971
Link to comment

Might need a pic or diagram of what you're talking about. I just helped A100addict with the same prob.....but danged if I can remember what he said fixed it. You might PM him and see if he remembers.


The screws holding the base plate to the body....you can only see with the carb off.....are the ones with the holes in the same place as the old carb?

Link to comment

Make sure its nice and tight(snug really) carb, manifold.


Now there is a brass screw at the base of the carb valve cover side. it will have a tension spring on there. try gently screw that in all the way counting the turns that you did. Then try turning it out in half turns and try starting the car/truck. do this till I say its out over 4/5 full turns then if it doesnt idle then is not your proplem. I would look as maybe the main jet is plugged as you said ealier in a post gas tank was full of crap/rust/dirt.But the idle jet usuaully plugs up first as the hole is very very small.


But I had this on one 521. I adjusted the mixture screw and it was fine after that. then maybe ajust the speed screw. shouldnt have to tune it in much. maybe a half it that.

Link to comment
  • 3 weeks later...

Well the carb without the brass jet at the bottom of the primary bowl was not the correct carb! Ordered another one from the local auto[shop] Correct one with the jet. This time fuel gushing out of bottom, checked gaskets, ok checked base of carb with straight edge. IT WAS A 1/16" of dia. across the bolt holes. No way it was going to seal. Took this one back also got my $$ back. Ordered a Weber 32/36. WOW what a difference runs better than ever!! Dont ever buy a re-man Hitachi. You never know what you are getting. Also lost my core in the proccess. Sheew

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.