Sluggish it seems, normal?

[josh817]

I rebuilt a stock L20B for my 521. L16 exhaust and intake. Timnig set at about 15º-17º at idle. This is where it starts best, and doesn't diesel when warm. I have a Weber 32/36 carb. Now... I bought it from someone on ehre and I think they said it was from a J13 motor. I don't know if they jetted it for that motor. Car starts up fine, runs fine, I just feel like a slug. If I were to keep up with trafic pulling from a light I would probably have to give 50% or more. Cruising down the highway doing 80MPH with a Z 5 speed (the one where ratios for 4th and 5th are really close together I think thats '79) and a stock rear end, I'm having to do at least 75-80% throttle. Flooring it will give me a little more. 1.75" exhaust. I don't expect much top end but I certainly don't feel torque when pulling away from things.

 

My question is if this is normal. I mean, stock rear end is geared real low, I would think I would be able to zip through gears and keep up. I do drive very modestly however and I am curious if my modesty plus the fact that the 32/36 DGV is a progressive throttle, perhaps that is why I don't scoot along like I feel like I should? Running off of the 32mm throttle plate most the time maybe?

 

My plugs all look perfect. Doesn't diesel, doesn't get hot, so I figured my carb was alright to do the job. I see 38/38 carbs and I'm curious but you know... the thing runs as is right now. A few weeks ago after a 3 hour drive on the highway doing that 80MPH at who knows, like 75% throttle, I was getting 29MPG according to the odometer. Granted my speedo is 10MPH fast so I guess thats more like 25-26MPG.

 

Thoughts? I've read the 1600 was a slug and you really had to floor it to get up to speed, make her scream when climbing a hill. 400cc more isn't really that much more, so I don't know if its reasonable to assume that having to do 75% to maintain 80MPH is normal, compared to flooring it... hah

 

 

Thanks guys.

[Tucson620]

I just completed my own L20B rebuild for my 521 with stock L16 exhaust and intake. And a used weber 32/36. :) 620 5 speed. So I know where you're coming from! I'm working some bugs in my driveline, but...

 

Sounds a little wimpy to me. 75% throttle would be into the secondary pretty heavy, no? Pretty sure I'd be 1/3 throttle or maybe 1/2.

 

Hopefully somebody else will come along and help. Good plugs, good mileage, decent running, just not as strong as you think it ought to be. :confused:

 

I had engine issues I traced to me being off a tooth on the distributor shaft during rebuild - my timing readings were thus always wrong. Advancing helped, but scared me (static to 25 degrees). One other possibility - your exhaust holding you back? You using the 521 L16 exhaust and muffler? 1.75" seems adequate, but any collapsed mufflers or whatnot?

[Tucson620]

Thinking some more - I think you should verify and post up your Weber jetting. Sounds like you aren't quite sure what's in there, just bolted it on.

[uberkevin]

Your going 80 in your 521 l16 motor???

 

I'm lucky if I hit 70 after the pedle has been to the floor a good minute or two.

I also have a weber 32/36.

 

There is a point on my trucks pedle where it gets stuck beyond the small

Bolt thing behind it.

 

Now you've got me thinking??

[uberkevin]

I'm slow nm. You rebult l20b...

 

 

Don't pay attention to me hahha

[datzenmike]

L20B timing is 12 degrees.

 

25 to 30 mpg is reasonable.

[banzai510(hainz)]

YOu sure the oil pump drive is in correctly? put it to TDC(zero) and ck for a 11.28 positon on spindal.

Is you dizzy closcked hard to one side to get this 17degs timming?

 

I got a L16 and yes its winpy but it can go up to 70 just fine(alittle loud)

Daily drive around town if fine.

 

open chamber L20s will diesel. with a 32/36.

[josh817]

I know for a fact that I didn't install the dizzy spindle correctly. The reason why I don't pay attention to it usually is because there are 4 ways to adjust the dizzy excluding the spindle. First two ways are with the dizzy hold down screws. You can twist the body, and the dizzy itself. The other way is to rotate your wires. If you are way way advance then rotate your wires counter clock wise by 1 (move them all one over) and lastly, with my Pertronix unit thing (its not really a pertronix its some one off thing that works pretty good) which I can rotate within the dizzy. Depending on where you place this pickup, dictates when it will fire, if that makes sense.

 

Anyway, I had gone into this before and got a lot of flack because indeed it is not the CORRECT way of doing things but that doesn't necessarily mean it won't work. Essentially, the distributor and the motor doesn't care which way your rotor is pointing unless you have it way off. I forget the firing order but lets assume its 1-3-4-2.

 

Correct way is like this or something close, right?

With the rotor pointing in the 11 o'clock direction. It isn't perfect but for the example we can label our plugs as such.

 

However, here is why it doesn't matter, consider the following:

My rotor is now point at 4 o'clock. It spins counter clockwise. Now it's stuck between two prongs (on a 6 cylinder, the gap between prongs is smaller so the difference between ridiculous advance and ridiculously retard is not as great). In this situation I COULD twist the body using the two adjustments, and if you can twist your pertronix pickup. Currently, it is way retard, because it wants to fire before it gets to prong 1 (remember the motor is at TDC #1 spark). I could use one of the dizzy adjustments and twist the body clockwise, thus moving the blue prong towards the rotor. This would help, but sometimes you run out of adjustment. That's why you can use the second body adjustment screw to get more if you want. Realize though that in the current orientation, if we labeled the yellow prong as #1:

It is now really advance. We can twist the body counter clockwise and we may get it to where we want. Because stock is 12º advance, it would be best, in this orientation, to go ahead and choose the yellow prong to be #1 because the amount of adjustment is less than it would be if we were to select the blue prong as our #1. Note that if you got lucky such as myself, and the rotor wasn't in the 11 o'clock position, lets say it was at 6 o'clock, it was positioned directly under a prong, therefore I labeled that prong as my #1.

 

It's all relative. The motor doesn't care which is why my timing is stable the way it is. I know it will make you frustrated though, Banzai. :rofl: Regardless, I have it set at 15º because it doesn't have a problem taking more advance. Doesn't ping or diesel, and its easy to start when hot and cold.

 

 

 

Anyway, I really should open up the carb to see whats in it. I truly did just bolt it on, and it worked well. Actually, the only thing needing adjustment was the idle mixture. She use to stumble and stutter sporadically at idle but now she purrrrs. It was too lean.

 

I'm not using a stock pipe. It's a 2" pipe but the muffler is small enough to slide within the 2" pipe snuggly. It was off of an 1800cc MG

so it's probably still undersized when I'm at highway RPM. The throttle position, obviously I'm just kinda guessing how far it's open. I know that when I was doing 80-85, and I went to pass someone, I stepped on it and noticed there was only at most .75"-1" of travel and then I was on the stopper. Yes, my full throttle on the carb is the same as the pedal stopper.

 

I get a little confused as to the metering of air and fuel the carb actually does. My thoughts are that if it were too small, I would expect it to be rich. Sucking in all this fuel but not enough air supplied, and it would show on my plugs. Yet, I have a second thought that since the fuel is drawn out by the air, and if the throats are too small, then there isn't enough air however because the fuel is dependent on the air, consequently you would have less fuel as well therefore less power. The velocity of the air though... is what creates the vacuum to draw out the fuel... which means a smaller throat, on a bigger displacement, more velocity, more fuel, richer environment. RAGE I DON'T KNOW ANYMORE THATS WHY I'M HERE. :confused: It should widdle down to the fact that it works now and its reliable, so I probably shouldn't mess with it, being my daily driver huh? hah

[datzenmike]

Larger motor needs larger jets on a same size carb I believe. If you are running lean this might explain being able to get away with more advance and also the poor power.

[banzai510(hainz)]

at TDC the rotor should be right ON with the timming plate in the center.

once you start up the you adjust to say 10-12dbtc.

 

if spindal is in corrctly

and you have a mismatched L20 matchbox dizzy with the other L20 pedastal(there were 2 versions and parts get mistmatched) the rotor can be inbetween number 1 & 3.

 

Be honst I dont think Weber is going to spend alot of time figureing out jetting when ell in a carb in the box.

I assume they but the best avaerge jets in there before they sell it. If the privios owner might have rejetted it. But do you really think he did???????

 

 

Essentially, the distributor and the motor doesn't care which way your rotor is pointing unless you have it way off. I forget the firing order but lets assume its 1-3-4-2.

True!!!!!!!!!

 

Im not saying its the carb but I have run 3 to 4 different weber DGvs on L motors from stock to a cammed motor and all run about the same and the 38/38 running rich and still runs good.

 

Im pointing towards the dizzy maybe its going out of time when it gets up to speed.

Plus the way you show your photos of the rotor almost inbetween the plug wires shows that its off.

The rotor itself the contack at the end is about 1/4 inch long. and the photo yourl still way off.

 

Ok Thats all im going to say.

I guess do a valve lash ck is next .

You ck the cam timming. The dash and V line up at Zero on crank?

 

also the fire order is Counter clock wise,Im sure you know this but those ddrawing will not work cause it shows you fire after TDC. on the top one and on the bottom one.

 

[banzai510(hainz)]

Just on another side note.

I had a dizzy that was loose bushing.

daily driving I wouldnt notice it. But I raced a old man in a beat chevy luv and got spanked. I said no way.

I notice I was cutting out on the top end. I thought it was just the carb. I find out the dizzy shaft was loose(even though I had a pertronix ignition on there).

I swapped out the dizzy and I was looking for that LUV to beat.

[josh817]

Good thinking. Do I just wiggle the shaft with the dizzy installed and look for play? How much slop is allowable? I actually just adjusted my valves, they were all right on or pretty close which made me happy. I didn't check the V notch in the cam to see if it lines up with the notch in the head right behind the sprocket. I've been thinking about that lately since that is an old chain and when I built the motor all I can remember doing is lining up the bright links with the marks.

 

Do I bring her up to TDC compression #1 and then check the V?

 

I will need to read up on sprockets. I have at least 5 of them laying around from Z's and the old L16. To my understanding the markings changed a little on them. Need to figure out what they mean to begin with! I remember some with #1, 2 marked on them and I heard something like flipping it around (or was it going from 1 to 2?) advances it by 4 degrees... Not sure. Even when I figure it out, is it best to just line the V with the notch or maybe have a little advance in it so the notch doesn't exactly line up? Who knows...

 

I actually just watched those videos from the How To board about it and thought to myself "gee, that's why people feel the need to buy a $250 adjustable sprocket" :thumbup:

 

Edit:

Watching part 2 and 3 of your stuff, see if that opens up any options.

 

Edit 2:

Alright I watched them and that made sense, rotating between holes. Just curious about the difference between holes and if you have some slack, but not enough to where moving over 1 hole over corrects it, should you go ahead and move it over or just not mess with it?

[dat521gatherer]

I have a similar problem. L16's are not wimpy. I can do 90 at 5000rpm and consistently do 70 at around 4000rms daily to work and back. weber 32/36 w53 head stock tranny and rear end.

 

Here's the thing in my 72 I have a l20b and it doesn't even compare. It's sluggish. Being rebuilt and a new in the box weber 32/36 should be faster than my l16. A few months ago I swapped out the points for a electronic dizzy. No change. When I open the second barrel it takes off but anything before that is sluggish. I also get after fire through my carb on quick punches on the throttle with the primary only sometimes. I think the primary jet is too small or something.

 

I'm going to swap carbs and see if there is a difference. Other than that all I can think it may be is my cam timing. I'm going to take my inspection cover off and see where the dash is.

 

I know this doesn't help you and not trying to thread jack but I feel your pain.

[wayno]

I understand why people want the distributor clocked correctly, and I understand that it will work in other positions also, but it is so much easier to fix things if everything is where it's supposed to be, so let's just assume that you do understand how to get the dist. timing set correctly where ever it is.

Turn the engine over till you are on TDC, and your rotor is pointed to number one, where ever that might be, pull the valve cover off and look at the cam lobe positions on #1 cylinder, are they pointed evenly between 10am and 2pm?

If one is at 11am, and the other at 3pm, the cam is timed wrong.

If it is reversed, 9am and 1pm, then it is wrong, these can cause slow revs/no power.

L20b engines use the number 2 dowel hole on the cam gear, and the cam lobes are at 10am and 2pm, anything else is going to create problems.

If you have your timing way up there just to get it started, and it doesn't knock/ping, that would make me suspicious that something isn't timed correctly.

[josh817]

I have a similar problem. L16's are not wimpy. I can do 90 at 5000rpm and consistently do 70 at around 4000rms daily to work and back. weber 32/36 w53 head stock tranny and rear end.

 

Here's the thing in my 72 I have a l20b and it doesn't even compare. It's sluggish. Being rebuilt and a new in the box weber 32/36 should be faster than my l16. A few months ago I swapped out the points for a electronic dizzy. No change. When I open the second barrel it takes off but anything before that is sluggish. I also get after fire through my carb on quick punches on the throttle with the primary only sometimes. I think the primary jet is too small or something.

 

I'm going to swap carbs and see if there is a difference. Other than that all I can think it may be is my cam timing. I'm going to take my inspection cover off and see where the dash is.

 

I know this doesn't help you and not trying to thread jack but I feel your pain.

As my father pointed out, its only 400cc increase. I don't know if it would truly be feel of your pants type material. And for your situation, I think it is along the lines of what I was saying before, being a progressive carb, that tiny throttle plate isn't going to do much at least that's my theory. I think I may play around with a vacuum gauge, kinda use it as a TPS. I will hook it up to the same line my dizzy is getting vacuum from which is coming off the carb so you don't get any vacuum until you crack the throttle. Maybe get a max reading, mark it, and see what it does while driving. Being critical today, I notice that I do give a bit of throttle when getting up to speed, nothing crazy. When at speed I can back off my a lot.

 

Tomorrow I will also check my sprocket. I wouldn't be surprised if I wasn't paying attention and just generically chose #1 dowel. After all, my manual is for 521's not 620's with L20B's.

 

To clear the air, I have the timing set higher only because I set it as high as I can usually, before I hear the RPM drop or before it starts pinging/dieselling/giving me hot start problems. It cranks, starts, and runs fine at 12º as well. Being in Texas, I was having hot start and a little bit of dieselling problems because I had set it wrong (that was also before I adjust the idle mixture so it was kinda running like shit anyway), found it was way too high so I backed it off.

 

Wayno, the cam timing can really be that far off and not show obvious signs like backfiring and bucking or really hard starts?

 

 

Back to you dat521, my Z always ran like shit if you stomped on it unless it was above 3000 RPM and that was with DCOE's. I never found out what it was. The truck doesn't stumble though. Too scared to floor it anyway. I could see something terrible happening the day before an exam or something.

[banzai510(hainz)]

I built the motor all I can remember doing is lining up the bright links with the marks.

You mean the dimples.?

If you got that IM 95% sure its ok.

whether sprocket being on #1 2 or 3 will be a differenc ,but I have never noticed.

Most chains I have seen, NEVER have chain stretch.

Im sure half of the L20s out there are set wrong to number 1 on sprocket. They seem to still be running.

 

If the cam is timmed with the crank. even if sprocket on number 1 you should be OK. I would look back at the dizzy.

You never said what type of dizzy you have and if it was pieced together from different part or cam as a whole unit(matching timming plate ect....)

 

tale a couple of photos at TDC with the rotor pointing shot and cap on shot. If rorotr is inbetween 2 plug wires it WRONG already.

 

521gatherer

I'm going to swap carbs and see if there is a difference. Other than that all I can think it may be is my cam timing. I'm going to take my inspection cover off and see where the dash is.

 

You have to take the valve cover off.

 

 

Josh as far as the bushing it was loose sideways but I figure since it was a electrical trigger is wouldnt know the differnce. But it was enought to make it cut out at the very top end.

 

 

Guys who buy adjustable sprockets are racers who need every once of HP out of there cams and get them dialed in.

[josh817]

Yup, set it to tdc #1 and my v lines up perfectly so that's good but my sprocket is on #1 (that's what is at the 2oclock position. Trying to make a wooden wedge right now. Looking for dimensions.

[banzai510(hainz)]

Personally I think your fine. if anyything should have more top end.

Maybe Datsunaholic or Datzen Mike might know more on L20s.

I have done L16 cam sprocket 1 and 2 and I cant tell the difference.

 

 

I think your waisting your time.

 

have you taken the dizzy out and spin it just to make sure the springs didnt explode?

 

 

take photos of it at TDC and show us. rotor position and cap on also

[banzai510(hainz)]

pne other thing.

put the timming light on there.

crank the dizzy to Retard snd see if you can reach zero. if not I will assume your dizzy is off a tooth or the plate needs better adjustment

 

rereading your post if your doing 80mph I assume everything might be fine.

Its not that your motor is a slug just that all the newer motors are BETTER and More POWERFUL

[josh817]

Meh still did it anyway just so I know it is correct as of right now. Here are some pictures, I will get a video of me flooring it too. I honestly think its just my driving style along with the carb being progressive and maybe not even tuned properly. I was thinking about it today and I'm never racing around like I did in the Z. I'm probably short shifting, leaving all the goodness up top untouched.

 

Only took about an hour, and that was with horsing around and making a wood wedge. Not bad at all.

 

@TDC

 

Timing mark on second tooth of the plate which is 0º

 

Where it was:

 

 

 

Afterwards, on #2 @ TDC the V was a little to the right of the notch, just a smidgen, like half the V was still lined up with the notch. I guess that constitutes 4º of crankshaft advance. Curious as to why the L20b needed to be advanced compared to the Z's and the L16's. Was it because of the higher deck height?

 

Nissan factory tool :thumbup: An old wire brush:

 

Real factory tool to use for dimensions:

 

 

 

Forgot to check the dizzy. :hmm:

[banzai510(hainz)]

Everything looks fine. slight V to the right is still perfect.

 

I just WANTED to see the dizzy cap on also to ref the plug wires from the rotor position.

 

 

I heard #2 was for emissions. I cannot verify this

 

 

Eric(Datto510) he had a 521 ans I cked the timming cam timming and said fuck it swap out a carb. It did the trick. its nice if you have these parts at home to trouble shoot. As when I was young you think one thing then its another.

So I alwasy to the engine timming cam timming ,valve lash then go the dizzy timming then the carb.