L16 stock carb: Will idle, bogs/cuts out when driven

[banzai510(hainz)]

Ok I mention before that you should have drained the anti freeze a bit. Now you have anti frezze in the ports and have to pull out the spark plugs and start the truck to pump all that anti freeze out outerwise youll compress it and break somthing.Unless this was just residue antifreeze that go in there but I have to say thats alot of antifreeze in there. Well it happen to me also when I was new to L motors.

 

I dont know why you pulled the whole exhaust manifold off. Was the Exhaustmanifold gasket leaky to the Y pipe below???????Otherwise you didnt need to pull it off just to change the intake/exhaust gasket.

 

To change the intake gasket you just pull it from the head a few inches to clear the studs clean the surfaces then put the new one on.

 

also that intake gasket looks like the later ROUND exhaust port oneThose are for the Later L20b motors. You need the 521 one. I assume you said say70-72 Datsun 521 intake/exhaust manifold gasket and he should have given you a square port type.

 

to ck the sendary port on the carb I would have rev the moto up then put my hand over the main barrel so all the vacuum wuould have went to the other side. and the 2nd barrel vacuum plate should have opened a bit then calmly went down.

Edited December 23, 2008 by banzai510(hainz)

[hessianben]

yep, coolant...

 

and no, the gasket is not the correct one- it was with a box of stuff that came with the truck- I'm waiting for the right one as well as one for the exhaust.

I ended up pulling the whole thing because there was a healthy exhaust leak at the bottom of the manifold-

it was actually rattling around separate from the 2-1 section. the loose stud that was causing it was the one that sheared off- so decided to pull it anyway to fix that.

there was some coolant below and around the intake mani-

that was my main concern-

I had initially feared a blown head gasket, but when it idles, I don't see any white smoke, so I am pretty sure that the coolant I had seen around the carb was from a leaky gasket.

[racerx]

Give this a try:

 

http://www.piercemanifolds.com/Carburetor_Set_Up_and_Lean_Best_Idle_Adjustment.htm

 

BTW their tech dept. is very helpful: Pierce Manifold.

 

 

Let us know what happened.

[racerx]

When you do change the intake gasket and after installation. Check for vacuum leaks. Once the car is running at operating temp., spray some carb cleaner around intake area, carb and it's base. If your RPM goes up then theirs a leak somewhere. Be careful not to tigthen the carb base just snug it.

[hessianben]

thanks RacerX-

that PDF looks really simple- and i likes pictchas for my simple brain!

Once I get it all back together, I'll use that method to check for leaks.

The other way is to stick your tongue anywhere in looks like there might be a leak,

and if it gets sucked in, you have a vacuum leak!

 

Personally, I like your way better.

[banzai510(hainz)]

if it idles then usually there is no vacuum leaks, otherwise it would not idle.

 

no idle= vaccum leak or idle fuel jet plugged

Idle then cuts out when gas is pushed= accell pump on carb or the main fuel jet is plugged.

 

car runs good untill high speed= pluggedd fuel pilter 2ndary jet maybe plugged.vaccume diaphrame has hole.

choke plate doesnt open fully cuasing a high speed air blockage(if a manual choke or automatic needs to be adjusted)

 

maybe ck the timming ,if poping ck the condensor if still has points.

otherwise I have no clue

 

 

hessianben

Im scare to change those lower exhaust gaskets. Im scare to break those bolts also. if possible use stainless ans BUY some Antiseize compound the HIGH TEMP stuff. youll use it on the thermostat bolts water pump also as it prevents corrossion

Edited December 23, 2008 by banzai510(hainz)

[datsunaholic]

He said it revs OK if he hand-operates the secondary. So I think the secondary is OK. Sounds more like the PRIMARY jet is plugged. EZ to check- pull the jet caps (below the float bowl) then check or pull the jets themselves.

[hessianben]

K: more newb questions-

 

I was studying the diagrams, but I couldn't see where to access the main jet-

and what are my options if it is faulty? what am i looking for?

when i move the throttle linkage, fuel spurts into the primary- this means the accelerator pump works, correct?

 

Also, the manual choke plate is just open right now- it seems to start fine without it. (the function is basically to let less air/more fuel in for starting, correct?)

 

Thanks guys!

[datsunaholic]

On the stock Hitachi, beneath the float bowl there are 2 plugs. You unscrew those and the jets are inside. Jets don't go bad, they just plug up from debris or fuel deposits. The jets unscrew as well, you just blow them out with air or if really plugged up you use a pin to get the crud out.

[hessianben]

You guys know a lot of stuff...

it's almost like...

 

you've worked on these motors,

before...

 

hmmm....

 

 

I'll give the jets a check-

are they the same size/diameter on the primary and secondary?

 

...and as far as the health of the points,

they get worn down over time, right?

so, if there is minimal material left, does that mean adjust the clearance, or buy a new cap? or can you buy the contacts themselves?

[datzenmike]

Look under the float chamber at the front of the carb. Beneath it on the carb base will be two 12mm hex plugs the lest one closest the valve cover is the primary. I have done this on the vehicle but much easier off. Use a rag to soak up the spilled gas.

 

Unscrew the hex plug. (don't loose the washer) You may find sediment in the gas that runs out. Using a narrow screwdriver reach up inside and loosen and remove the brass primary jet. They are soft so fit the screwdriver carefully. I had to use a wide blade screwdriver and grind the sides down to get it to fit through the opening and still grip the sides of the jet. You'll see what I mean.

 

L16 primary will be in the neighborhood of a 97 jet size. Secondary about 170 or so. Too many carb options to list but the primary will be the smaller of the two.

 

I like to get the cans of carb cleaner with the tiny red straw like the WD-40 cans and use them to poke up inside and spray the internal passages to clean them. Try that and it should spray out into the primary barrel. Wear goggles, that shit stings! You might want to take the carb top off and remove the air bleeds above the emulsion tubes and blast them with spray as well. This will spray the reverse direction.

Edited December 23, 2008 by datzenmike

[racerx]

Car's still idle even if it has vacuum leaks. Sometimes the vacuum leak is not much. If you can get rid of that Hitachi carb and buy a 32/36 weber. You will notice some gains and it's so easy to install and adjust.

 

 

 

 

if it idles then usually there is no vacuum leaks, otherwise it would not idle.

 

no idle= vaccum leak or idle fuel jet plugged

Idle then cuts out when gas is pushed= accell pump on carb or the main fuel jet is plugged.

 

car runs good untill high speed= pluggedd fuel pilter 2ndary jet maybe plugged.vaccume diaphrame has hole.

choke plate doesnt open fully cuasing a high speed air blockage(if a manual choke or automatic needs to be adjusted)

 

maybe ck the timming ,if poping ck the condensor if still has points.

otherwise I have no clue

 

 

hessianben

Im scare to change those lower exhaust gaskets. Im scare to break those bolts also. if possible use stainless ans BUY some Antiseize compound the HIGH TEMP stuff. youll use it on the thermostat bolts water pump also as it prevents corrossion

[hessianben]

I'm all for the Weber-

question- do all 32/36 Weber carbs have the same flange, linkage, ect...

or do I have to buy a Dat specific kit?

 

will this one work?

what else would i need?

 

http://losangeles.craigslist.org/lgb/pts/962046748.html

[hessianben]

EDIT:

 

I know that one has electric choke. I will need to find manual type.

 

what other makes can use this same unit?

I see BMW, VW, Toyota, ect... in the tag lines.

[racerx]

Most 32/36 will fit with the right adapter but the site I told you to check out pierce manifolds should be able to help you or weber direct. There's different variations of 32/36, there's auto choke, manual, some are mirror opposite and some are water, maybe 5200 Holley version which is copy of weber 32/36. The reason why you want to be specific with application is some are jetted for a specific size engine. You can buy a new one for like $270 or so and maybe $35 for adapter. If you do get the adapter tryt o get one that's a once piece and make sure that the filter that comes with it will not hit the hood, since there are different sizes. Like I said call Pierce manifold or weber direct. You can go on line and find their website or give them a call.

[banzai510(hainz)]

there is a little more than that to install a DGV but its really simple.

 

I suggest you just man up and kit a New kit!!!!!Webercarbsdirect.com

It has the adpater and cable mount kit with it. A A32/36 DGV 5A is the cheapest and is the manual version.

 

Otherwise if you part one together youll need to find a adapter plate which are cheap. the the stock 521 cable holder has to be modified(slotted) and the stock 521 cable pully thing the cable slips into can be used on the weber(like it was designed already to be converted) will fit on the weber but maybe has to be shimmed a bit so the cable angle fit better so the cable dont bind.

 

also some later cable assemblies had better or worse carb spring return systems(means you rig up a return spring some how) My 72 was a later electric choke truck and it was perfect.

[racerx]

I prefer a manual choke over electric choke or water choke. I just had better luck with manual.

 

EDIT:

 

I know that one has electric choke. I will need to find manual type.

 

what other makes can use this same unit?

I see BMW, VW, Toyota, ect... in the tag lines.

[mike]

On that snapped exhaust flange bolt, take a grinder and grind it flat with the mating surface, then take a hard punch and make sure you get it dead center (if you scribe an x in it it usually helps) then drill it out, starting with a small and going larger. You might get lucky and get enough heat on it from drilling to be able to back it out and reuse the original threads... I wouldnt bet on it though. If you drill straight through you can put a stainless bolt in from the top, just make sure that the head fits flush and it isnt cockeyed, if you tighten it crooked it could snap the flange and then youre screwed unless youve got another mani. You can grind the head of the bolt a little to make it fit perfect.

If you do one like this you may as well do all three since youve got it out.

I would not suggest an easy out by any means.