521 only runs well when choked a little

[Dats Right]

workin on the 521 today, just put carb back together with rebuild kit, was having trouble getting good squirt from accelerator pump, old one was too tight, the new leather one with kit also too tight once swelled, so ended up shaving old rubber one down and got it to work best so far, good squirt though kind of ghetto method to get it, thought that was my problem because when i would press gas motor would die blow a little smoke out carb, so anyway adjusted timing, idle and mixture screws, and it sounds nice and runs and drives great when manual choke is pulled out about 3/4 inch, when pushed in it just stumbles and dies. Am I running lean, or am i just not warmed up enough, if lean do i fix that with mixture screw, tried datzenmike method of turning mixture screw in till sounds bad then out till sounds bad then put it in middle, but when i turn out cant hear much change even when all the way out. Thanks ratsun to all info to get me to this point, hopin for some more advice on this one, thanks, threw in pic of truck for the hell of it

 

[thisismatt]

Did you pull out the idle jet and make sure it's not clogged?  Had the same issue recently while cleaning my carb.

[datzenmike]

It's usually warmed up after about 10 minutes of driving, give or take depending if extremely cold or not. A cold motor will not fully vaporize the cold fuel and will act like it's lean. A lean backfire through the carb would be normal. The choke forces an over rich condition so the engine will run properly when cold.

 

Any carb adjustments like idle speed and mixture must be made when the engine is thoroughly warmed up.

 

If it refuses to idle below 1,000 RPM the idle circuit may be blocked.

 

If it refuses to run properly above idle when warm the primary jet may be blocked. . 

[Dats Right]

i recently cleaned and blew air through all the jets, think they are ok, is there an easy way to read rpm, no tach on vehicle

[Dats Right]

I think the vehicle possibly wasnt warmed up enough, ran it in the drive way and took it for couple mile cruise but the temp outside is only about 45 today

[Dats Right]

If the primary jet were somewhat blocked would the vehicle perform well when partially choked?

[datzenmike]

The choke will force a rich mixture. If it runs well with choke then this supposes it must normally be a bit lean to begin with. A clogged jet is likely.

 

Are we talking idle or running when driving?

[ggzilla]

Yes

If the primary jet were somewhat blocked would the vehicle perform well when partially choked?

Too little fuel causes this, like if the fuel-cut solenoid is unhooked. So does too much air, like if the gasket is torn or the air bleed jet at top of carb is loose.

 

If your temp gauge is near the middle, it should run well with choke off - even at 45 degrees.

[Dats Right]

The situation occurs at idle and while driving if the choke isnt pulled a little it dies when idled , and while driving it stumbles and boggs down when gassed , I will go over the jets again and check the fuel cut solenoid, i am not sure if it is wired up properly, is that the same as the "deceleration solenoid" the one  on the side of my carb, thanks much.

[Dats Right]

Correction, at idle it dies when i press down on gas , it will run fine at idle when gas isnt touched

[Dats Right]

not sure which jet is the primary and which is air bleed, still havent found exact schematic drawing of this carb, should i just blow them all out again

[ggzilla]

Don't bother. Start by tightening the jets on the outside of the carb - but only if they are loose. Don't overtighten them. If that solves the problem you are done.

 

You will need to adjust the idle again if any were loose.

[Dats Right]

ah i like the sound of that,trying to avoid disassembling carb again thanks

[DanielC]

It is very difficult to tune a carb without a tach,, and a vacuum gauge, and pretty easy with them.  You need get an old school Dwell -tach meter, and use that to set the idle RPM.  The vacuum gauge will show you a change in idle mixture before you can hear a change.

 

you also need to do all the other tune up stuff before you adjust the carb.  Set valves, adjust timing, warn the engine up, all that.

[banzai510(hainz)]

no idle ck the idle jet.

if idle and punch the gas ck the acell pump.

 

also do a basic timming ck to make sure your timming is half way close as it might make it look like another proplem(carb).

 

Daniel is good but just to let you know I never owned a vaccum gage or dwell meter. Youll know if your getting this correct, But Hitachis suck once they wear out. I love them New but I could never get them right trying to mess with them once worn out.

[ggzilla]

Dwell meter is only needed to set points gap on used points.

 

Dwell-tach meter is the most common type of handheld tachometer. You need a tach to set the idle speed to spec, for best fuel economy and emissions. But otherwise the engine will run OK idling too low or too high. Most dash tachs are not accurate in the under-1000 rpm range.

 

I used a vacuum guage a couple of times, but felt it was easier to adjust the carb by ear. If you can hear the engine slightly speed up and slow down, you can do it without a vacuum gauge.

[Dats Right]

Thanks rebuilt the carb and distributor, set the new points with a feeler gauge, old point were almost touching it had been a long time since anyone had been in there, shaved down my accelerator pump so it fit better, wasnt traveling freely before, then finally got timing light i ordered and set that, which barely lines up when advanced fully on dizz screw, but good enough i think, then set carb screws by ear and vibrations , shooting for minimal vibration, oh yeah i also find tuned float level and re adjusted valve clearances, sounds pretty damn good so far, cant believe i was even operating this thing before. mahalo

[DanielC]

There are two bolts on the distributor to set timing.  There is one bolt, that you can see easily, that goes through the plate down into the pedestal, and there is a second bolt under the distributor that goes up through the plate into the distributor body.

This is the plate I am talking about.

[Dats Right]

The one i am refering to is the bolt that when loosened you are able to turn the flathead screw that moves the distributor,  soyou are saying there is another adjustment that will give more room to advance, when loosened how do you adjust?

[ggzilla]

Since you got the timing right, no need to adjust the plate.

 

So it runs well now with choke off?

[DanielC]

In this picture, you can see the bolt going up into the distributor body.  Look below the temp sender wire, and the bolt you can see that holds the pedestal to the timing chain cover.  It has an eight MM hex head.   Back behind the distributor, is the other bolt that you can loosen to adjust the distributor timing.  It has a ten MM head.  Directly below the matchbox, the black box, on the distributor, is a tab going forward, on the distributor pedestal.   It has a mark, or a line on it.  The steel plate, in my above post, has marks on it showing timing advanced, and retarded.

 

If you loosen the bolt going down through the plate in to the pedestal, the plate moves with the distributor, and the indexing marks change.   If you leave that bolt tight, and loosen the bolt going up into the distributor, you can move the distributor, without moving the plate.

 

 

[Dats Right]

I think so, but not positive that im out of the woods yet, havent had a chance to drive it a lot, since i had to put it on blocks and fix all the brake adjusters and a crumbly brake line, i will let you know after i am able to run it a bit more.

[Dats Right]

That last response was to the previous question if it was running good with choke off, thanks for the distributor pic, i think my mounting setup on j15 a bit different than yours, but generally the same. Dizz is on othe side of engine, and appears that plate is similar but in different orientation. i see the upward bolt you mention and im going to check mine out to see if i also have that one. I was able to just set it  to 6 btdc, which is spec. but at least would like to know if this bolt is snug on mine.

[banzai510(hainz)]

they make a pertronix ignition conversion for the J motor dizzy.

[banzai510(hainz)]

http://vintageperformance.com/retrorockets/Datsun/nissan.htm