1970 Datsun 521 L20b running rough.

[Dennisbeechie]

This truck has been a pain in my ass from the get go. The issue I'm having seems to be progressively getting worse. When I first got it, it idles fine and and drove decent, unless I hammered on the gas then it would bog down and back fire. It has a Empi 32/36 electric choke carb. I have adjusted timing to 12 degrees, new plugs, new cap and rotor, points and condenser seem in good shape, adjusted the fuel/air screw, put a fuel regulator on it, seafoam in the gas tank and oil, new glass fuel filter, rebuild kit on the carb (new gaskets, o rings, accel pump). Now it idles ok but if I give it any gas it bogs down, if I put it in gear and go down the road, I can get through 1st 2nd slowly giving it gas and when I get to third it wants to stall and die, I have to shift all the way back to first and feather it back home, then when its parked it runs fine again. I'm at a loss I hope someone can give me some ideas on what to look for. It sat overnight and I went to start it up after that short drive down the road and back it would not start, no spark at the coil. I cleaned/tightened any contacts going to the coil, ballast resistor, distributor, and magically got spark again but the same issue with it bogging down. I'm thinking maybe the float needs adjusted or new points and condenser, maybe the jets are too big? Too little? Idk. I got this truck to learn how to do these things, and its definitely a perfect learning experience. Thanks for your time guys and sorry for rambling.

[Draker]

It's possible it's jetted wrong.. but if it's the carb that has been on there for some time.. it's likely something else. If you are running a stock fuel pump with the stock spacer, I'd ditch the fuel regulator. No need for it at all. It's more than likely just the carb. If it's an old carb, some times even a rebuild isn't enough. Might have worn throttle shafts or something?

 

What do your spark plugs look like?

 

I've been your exact position with a weber 32/36. Rebuilt it, top to bottom. cleaned it all up, adjusted everything. It ran ok. Idled a little weird, bogged down if you jumped on it hard.. never could get ride of that. I still have it sitting in my garage.

 

If it were me, I'd just ditch the carb and run a weber 32/36. Buy it new, and never look back.

[banzai510(hainz)]

the timming is set to 12deg. But is it in the middle of the timming plate?  If you have the dist crank to one side to get the 12btdc then you moight be off on the oil spindal or a wrong distributor pedastal.

 

the empi carb is a made in china unit and not to many people know about these. This puts a big question mark on your situation.

 

also hopefully you still have the stock coil in there also. as its a match set with the ballast resisitor.

 

Us Ratsun guys will assume when this is warmed up the choke plate is open pon the carb. so it not choking up when you drive faster.

 

dist may be worn.

 

But you need to be more specfic bad since the get go?. Has this ran good at all? if not then IM thinking dist is off.

Now get a timming light and when its warm and at idle. move the dist  and see if you can get the light to read 0 to 25btdc. If YES then Im 95% for dist is timmed ok.  If not and your cranked all to one side on the dist then I think your off a tooth.

 

 

 

This is a simple fix  wheither its a carb or dist I will assume the cam is timmed and the valve lash adjustment is good also.

ck the distributor for side to side wear. and vaccum advance moves

 

You seen my vid on youtube. hainz Datsun L series. watch that about 1000times.

 

olddatsuns.com the tech section

[datzenmike]

Sounds fuel related. First and second don't need a lot of gas but third the pedal goes down more. Carb open but not getting enough gas and too much air.  Could be the float set too low and running out or jetting too lean.

 

Pull fuel line off carb and aim into a pail. Pull coil wire off so it won't start and crank it over. You should see strong spurts of fuel coming out. If not change the fuel filter or make sure the fuel lines are clear. If fuel delivery is good .....

 

Check the float height. I don't do Weber carbs only the sock ones so you're on your own. If the float is too low the carb can use gas faster that it can get in and it runs out, but when you stop it idles fine.

 

Warm up and take for a romp in first or second around the block and then pull the plugs. If they are very light or even white the mixture is too lean.

[Draker]

I do have a stock L20b carb you could have. It's from a 620. Condition.. unknown.. Never ran it.

[Dennisbeechie]

Thanks for the fast reply guys! I will be checking on your suggestions in the next day or so, datzenmike, I have felt this way since the beginning that it is fuel related so I'm going to be checking that and hainz you say the dist. May be a tooth off? That doesnt sound too far fetched seeing how to the screw on the timing plate is pretty far advanced... Also you were asking if it ever ran well, it has never let me give it full throttle without cutting out...Draker I may be interested in taking that carb off your hands, its a Hitachi? Everything there? Thanks again, you guys are awesome. Ill try and get some pics also

[Dennisbeechie]

I really dont know alot about the mechanics of the vehicle, I got the truck pretty much the way it is and I'm learning as I'm going. Some of the things described are foreign to me. before long ill be YouTube/ratsun/Google certified lol. The choke is wide open when its warmed up, I have no clue what a oil spindle is, but I'm doing some research to figure it all out.

[banzai510(hainz)]

watch the vid first.

 

Maybe last guy sold the truck cause he put it together wrong.

 

 

get truck running. Now cycle the linkage and you should see gas squirt from the main barrel  every time you cycle it on the down stroke(as if your hitting the gas pedal)  this shows that the fuel bowl is most likely full and the accell pump on carb is working

[Dennisbeechie]

watch the vid first.

 

Maybe last guy sold the truck cause he put it together wrong.

 

 

get truck running. Now cycle the linkage and you should see gas squirt from the main barrel every time you cycle it on the down stroke(as if your hitting the gas pedal) this shows that the fuel bowl is most likely full and the accell pump on carb is working

I checked and there is a solid stream from the accel pump jet and also has coming from the venturi.

[Dennisbeechie]

Also in the process of watching your videos, and I will probably watch a million times, very well made

[Draker]

Thanks for the fast reply guys! I will be checking on your suggestions in the next day or so, datzenmike, I have felt this way since the beginning that it is fuel related so I'm going to be checking that and hainz you say the dist. May be a tooth off? That doesnt sound too far fetched seeing how to the screw on the timing plate is pretty far advanced... Also you were asking if it ever ran well, it has never let me give it full throttle without cutting out...Draker I may be interested in taking that carb off your hands, its a Hitachi? Everything there? Thanks again, you guys are awesome. Ill try and get some pics also

 

 

I believe it's all there. It's a Hitachi. I got it in a pile of parts.. so it could be good. It could be bad.. but it's yours if you want it. 

[Dennisbeechie]

I believe it's all there. It's a Hitachi. I got it in a pile of parts.. so it could be good. It could be bad.. but it's yours if you want it.

I sent you a message, thank you

[datzenmike]

If you can rev it up in neutral, like way up there, but it won't run under load, probably not the distributor, probably.....

[Dennisbeechie]

If you can rev it up in neutral, like way up there, but it won't run under load, probably not the distributor, probably.....

yes I can hammer on it in neutral no problem

[datzenmike]

Then the distributor is not likely advancing past the plug wires on the cap.

[Dennisbeechie]

Then the distributor is not likely advancing past the plug wires on the cap.

...where should I start?

[banzai510(hainz)]

where you start?

 

Buy a timming light. But you say its on 12btdc so you must have one.

 

 

ok another way is line up the crank pully to zero on the timming pointer. then pop the cap and see whee the rorot or pointed on the cap and see if its close.

 

 

 

ok get a mini c clamp and readjust the dist till it runs better under load and lock it down. If off a lot to run  then the dist spindal is off

[Dennisbeechie]

where you start?

 

Buy a timming light. But you say its on 12btdc so you must have one.

 

 

ok another way is line up the crank pully to zero on the timming pointer. then pop the cap and see whee the rorot or pointed on the cap and see if its close.

 

 

 

ok get a mini c clamp and readjust the dist till it runs better under load and lock it down. If off a lot to run  then the dist spindal is off

yes I have a light, and I will set the crank pulley to 0 and check the rotor tomorrow

[banzai510(hainz)]

you will know your on compression stroke when you dial up to number 1 when the cam lobe you see thru the oil filler hole is close to the 9 oclock position  then dial it up to zero on crank and it should be like in the 10 o clock position on the cam lobe. then look at the rorotr to EXACTKY where it points.

 

or do what I say in post 17

[Dennisbeechie]

Well I pulled the dizzy, looked down in there and seen this... I pulled the oil pump and reposition it to what I thought was 11/28 position, now it just back fires and won't start... I'm guessing I put it in 180 degrees off? Hopefully.

[Dennisbeechie]

I'm gonna get back into tomorrow if the weather is halfway decent and try again

[banzai510(hainz)]

that looks right.   YOu watch the vid??????????

now when you put the dist in where those the rotor point?

 where rotor points that is number 1 plug wire. then goes 1 3 4 2 counter close wirse fire order.

 

a lot of people say Im out 180degs. then move the spark plug wires 180degs and start over. key is the above statement. If you know where 1 is then that is your starting point. 1 3 4 2 ccw.

 

but like I earlier said the oil spidal can be correct at TDC but you have a wrong distributor mount if you converted this over with mismatched parts. If this was running fine before then put it back to where ever you had it.

[Draker]

Typically the fat side of the 'tang' is pointed to the back of the engine. I'd assume you are 180 out now.

[Draker]

If the weather isn't shit, maybe I can swing by sometime this weekend and we can get it squared away. If you don't have it running by then of course.

[datzenmike]

Well I pulled the dizzy, looked down in there and seen this... I pulled the oil pump and reposition it to what I thought was 11/28 position, now it just back fires and won't start... I'm guessing I put it in 180 degrees off? Hopefully.

 

 

I'd say 180 out.