521 break in complete!! (4 issues)

[haze]

so this weekend i took my little booger green 1972 521 on a little 600 mile jaunt to east texas to break in the new engine (did the 100 mile oil change at a rest spot) drove her hard no consistent idles. about to do the 500 mile oil change this afternoon. i have 3 issues i could really use some feedback on....

 

1. DIESELING: there is a webber DGEV 32/36 reused on this rebuild. it was professionally tuned by a certified mechanic and she diesels badly i was wondering if octane booster would aid in this problem? i am putting her in third and releasing the clutch at shutdown to aid in this problem but every once in a while i get a bad clunk engine stall sound

 

2. MECHANICAL FUEL PUMP: about 300 miles into the trip the mechanical fuel pump went tits up. basically the actuating arm on the pump disconnected from the metal pin that actuates the diaphragm. this is a brand new fuel pump purchased from orileys. i put the arm back on the pin and the pump worked again however the spring that connects the arm to the body of the pump is MIA and i fear that it may be in the engine somewhere. i havent noticed any issues with the engine itself but was wondering if i should look for this thing and where i should start OR if this is a "if it aint broke dont fix it" type thing. i am replacing the pump this afternoon hoping it wont happen again.

 

3. HIGH IDLE BETWEEN GEARS: i noticed this more towards the end of our 600 mile journey.anytime i began accelerating the engine would rev high between gears. the issue was not so bad clutching and coming to a stop out of say 3rd or 4th.

 

4. DIFFICULTY STARTING: cold start is great but after she has been running for a few hours i have to turn the key longer and pump the gas to get her to cough into life

 

 

again thank you all so much for all the great advise so far i couldnt have rebuilt this little booger without ya'll!!!!!!! its because of you guys there is a extra datsun running on the streets of america today.

[banzai510(hainz)]

1)Dieseling is common on open chamber head L motors. later Hitachis had a anti desieling selinoid.with a 12volt wire.

 

2)Fuel pump should have a spacer between the head and the pump. If not the pump arm Will bend and break. Maybe you had the spacer and just a bad pump. I ran those pumps before and had not proplems.

 

3 ) You adjust the cable and oil it up. also on 521 s they should be a stock datsun return helper spring besides the 1 on the weber.

 

4) ck the timmming again. and ck the valve lash to make sure your valaves are closing and intake carb is tight.

Is this a manual carb or electric?

[haze]

1)Dieseling is common on open chamber head L motors. later Hitachis had a anti desieling selinoid.with a 12volt wire.

 

2)Fuel pump should have a spacer between the head and the pump. If not the pump arm Will bend and break. Maybe you had the spacer and just a bad pump. I ran those pumps before and had not proplems.

 

3 ) You adjust the cable and oil it up. also on 521 s they should be a stock datsun return helper spring besides the 1 on the weber.

 

4) ck the timmming again. and ck the valve lash to make sure your valaves are closing and intake carb is tight.

Is this a manual carb or electric?

 

 

the carb is an electric choke

[banzai510(hainz)]

electric

this could be a adjusting issue when motor is still warm and choke plate is in the wrong spot.

This is where I like manual carbs.Once I adjusted a eleltric choke carb it never was good after that. It was either to much choke to long or not enough.

I just crank it back choke plate till its OPEN(lock it down) and pulled the wire off and just pump the gas to start and feathered it till its warm.

[haze]

well i just shot some wd40down the acceleration cable housing and lubed the moving parts on the carb as well, changed out my fuel pump and spacer. there is a return spring on my gas pedal and that whole area has a bit of grind when i push it with my hand but the cable definitely still has slack when i release the pedal. about to drive her to the parts store for some more oil i'll keep you posted.....

[ggzilla]

she diesels badly

* Check the idle speed. Anything above 600 RPM is likely to diesel

* Before using octane booster, just try a tank of premium. If that doesn't help neither will octane booster

* Check the timing at idle, put it at factory setting. Distributor should have 0 vacuum at idle.

* Temperature. Use a 180-degree thermostat instead of 190-degree

[ggzilla]

cold start is great but after she has been running for a few hours i have to turn the key longer and pump the gas to get her to cough into life

Normally warm do not pump, but hold pedal partway down.

 

Here's how to start a Datsun with WARM ENGINE per the original instructions:

[haze]

HAINZ

i am a retard and did not put the spacer on my mechanical pump. i just compared my new pump with the one that was on my engine prior to rebuild and the arm and mounting flanges were the same size. for some reason i was under the impression that parts like new fuel pumps sold at auto parts stores are designed to fit a hand full of vehicles and so some of the parts out of the box were not needed........ stupid f-ing me. problem solved spacer attached (i was probably just pushing way too much gas)and she no longer revs between gears though her RPM's still seem to be just a little bit high while i am driving around so i popped the hood and jiggled the cable just a touch and she definitely idled down. picked up a few help throttle pedal springs to see if i can put a little more bounce in her step also grabbed a can of sea foam just in case my very slight idle problem is just a bit of varnish in my reused carb

 

GGZILLA

your diagram is AWSOME!!!! that shit really made my day and works like a charm!!!! i believe my little booger has a 180 thermostat on her now but those things are cheap so i will switch her out just to be sure. timing is set to right around 750 to 800 rpms according to my mechanic, the label under the hood and my ears but i dont have a tach so i cant be sure. she is a fresh rebuild, is it possible she is just running hot due to the newness of everything? i will definitely give that premium a shot and let ya know what happens after i burn thru this tank of shit fuel been reading on here about only using techron gas. i am going to drop in some premium and a bottle of seafoam and see what gives ..... i really love that diagram man!!!

[Laecaon]

I had bad dieseling on my fresh rebuild. Idle was at 900rpm, any under and it was way to rough to even sit in the car. Well I messed with the idle mixture screw, and my rpms doubled. I was running way to lean at idle. I then turned my idle down to 800rpm and it was smoother than before. I have not since had a dieseling problem.

 

Dieseling, higher octane to resist predetonation would probably work, but I think it is a waste of money if your motor doesnt ping with loads. I would say just richen up the idle a tad so it is harder for it to diesel (easy to ping/predonate a lean mixture).

[banzai510(hainz)]

Haze My 521 has a U67 head

It deisels like a Mother Fuker with regular or super even on HOT days.

Just the way it is.

 

When I had my 38/38 weber on there I would just crack the throttle abit more right when I put the key to Off to leesen the vaccum to idle circut

[haze]

thanx ya'll think i am going to start this off by trying out what HAINZ said and cracking the throttle before shutting her down (simple shit first right?), then put a tighter spring on the throttle pedal and seafoam in the tank with some premium gas (just jiggling the throttle cable definitely lowered my rpms though the cable is slack at the carb and free moving in its housing) and see if there is any improvement, after that i am switching to regular grade gas (there is no way i can afford to only run premium), and see how she does. if its still an issue i will start dicking with the carb like LAECAON mentioned (i'm a pussy and carbs intimidate me). basically what i am doing now is stalling the engine in third multiple times a day am i correct in thinking this to be a bad thing?

[wayno]

thanx ya'll think i am going to start this off by trying out what HAINZ said and cracking the throttle before shutting her down (simple shit first right?), then put a tighter spring on the throttle pedal and seafoam in the tank with some premium gas (just jiggling the throttle cable definitely lowered my rpms though the cable is slack at the carb and free moving in its housing) and see if there is any improvement, after that i am switching to regular grade gas (there is no way i can afford to only run premium), and see how she does. if its still an issue i will start dicking with the carb like LAECAON mentioned (i'm a pussy and carbs intimidate me). basically what i am doing now is stalling the engine in third multiple times a day am i correct in thinking this to be a bad thing?

 

I have been shutting down my work truck in gear for over 15 years now, if I don't, it diesels badly.

I have been doing it for so long, I don't even notice doing it anymore, I cannot imagine how it would hurt my engine shutting it down this way, it's better than listening to it dieseling for half a minute, and then rev and knock when it finally does die.

Fact is, no one would even know that's how I shut it down, unless I told them.

[ggzilla]

is stalling the engine in third multiple times a day am i correct in thinking this to be a bad thing?

 

Not a bad thing, won't hurt the engine. A bit annoying to have to do is all. You'll get used to it. What is your RPM idle? Can you get it down to 600RPM, most engines won't run-on at 600 RPM, but will at 750RPM.

[haze]

UPDATE: so i ran the seafoam and my idle went straight to shit after about 2 days of driving local at which point i realized i had to drive my lil mamma hard to kick all the gunk out. well about 4 miles down I-35 my second brand new fuel pump went tits up just like the first (the mechanical arm disconnected from the piston and another spring popped off inside the engine somewhere) and yes the spacer was attached this time. anybody have any thoughts on this? i'm thinking about going electric but at this point i am not overly excited about cutting up my metal fuel lines so staying mechanical is definitely the preference. anyway after putting the arm back on the pump i took my little tiny truck about 250 miles via the highways with a little more seafoam in the tank and maintaining a speed of about 60 to 70 mph and though the idle does sound a little bit better she is still shakey, studdery and via my untrained ears idling high. i did change the fuel filter after my trip.

 

gg, wayno you guys sold me on the shut her off in third thing. my paranoia is relived. thank you

[ggzilla]

via my untrained ears idling high

This is set by the idle speed screw. But first you need to get rid of the shakiness. A vacuum leak can cause shakiness, stuttering (hesitation), high idle AND run-on (dieseling). It can leak from a bunch of places including distributor, air cleaner motor, and choke pull-off

 

my second brand new fuel pump ... anybody have any thoughts on this?

Yes, my thought is stop buying brand-new fuel pumps. The aftermarket pumps are often JUNK. Instead, get a used genuine Nissan fuel pump. Mine is 40 years old, still going strong. All I've done to it was take the top off and clean it out about 4 years ago. Or, if you prefer, you can buy a new pump from Nissan.

[josh817]

Oh oh oh, I have a pump if you want. lol Me thinks its easier to just go electric with a mechanical in the parts bin as back up.

 

Weirdly my motor never deisels.. Actually thats a lie, it did once for a split second. I just hold my foot down on the throttle and it dies out. My timing is set to 15 or 16º at idle with the vacuum line hooked to the carb.

 

The high idle you may need a stranger spring. With my Z, I always had that happen on triple webers where if I gently let off the throttle that would every so slightly stay cracked to where you would have to lift the pedal with your toe. Just a tiny amount of crack yields an idle the use to be 1200 up to 2200. Sometimes it wouldn't do it if I completely let my foot off the gas and let the throttle plates slam shut.

 

 

By the way, with whatever motor you're using, 1300/1600/1800/2000, is your truck relatively quick? My truck with a five speed, stock rear end, and an L20B.... when I floor it I'm accelerating as quickly or just slightly quicker than cars pulling away from the light at normal speed... Figured it's just a 521 thing. :poop:

 

Good luck on your motor.

 

 

I found this old video I made when I was breaking in my motor. Last 10 seconds you can hear the idle way high, so I blipped the throttle and like I said before the plates slam shut thus giving me my true idle that I intended for.

[haze]

UPDATE #2 put the original pump back on the truck and then drove 900 miles to denver with no issues however now my truck doesnt start checked my fuel lines for pressure and the plugs for spark. she turns and fuel is making it to the carb however she is not turning over please help i am stuck in denver until i figure this out

[ggzilla]

So when you turn the key to start, the engine does not turn? No rotation at all? What does happen, any sound?

[haze]

it sounds just like a bad fuel pump but the pump is pushing fuel, the starter works fine and the engine will turn. every once in a while she sounds like she wants to catch for a half a second but doesnt. i fear it has something to do with the carb because i am getting fuel all the way to it and plenty of spark. the funny thing is there were zero issues all the way to denver i parked in front of my buddies house hung out for a few hours then jumped into the truck to grab some grub and she decided she no longer wanted to turn over. i am about to head to the gas station for a bit of fuel to try priming the carb. but right no i have a big old question mark over my head.

[haze]

so i primed the carb and she started right up however i have to rev the engine for a couple of minutes to keep the truck from dying could my issues be an elevation thing? austin is pretty much sea level and denver is pretty much the rocky mountains?

[flatcat19]

The elevation could sure have an effect on drivability to your carb'd vehicle.