Jump to content

1980 L20B Newbie


Humboldt

Recommended Posts

Hi everybody-

I just aquired a 1980 720 with (ahem) 91 k miles. I want to get this thing pepped up. My son has a 510 we worked on with pick-a -part excursions when he was a teen ten + years ago. He has some parts. I am in Cali but I want to dump the smog complications and simplify the motor. That is my goal. I don't have any ethical issues with that. It creates more pollution to manufacture  a new gas guzzler than to keep this choice vehicle in service! I don,t want to lower it, etc., I am 63 years old. Hell, I drove Datsuns off a cargo boat in Seattle when the kid was in diapers. B210s- yetch.  So.o. . .  Has anyone had experience stripping off the air pump, catalytic, pollution control etc. off to get this '80 L20 successfully to be an efficient Grandpa Hauling Machine? Compatible manifolds, gaskets etc. . . . What to remove and what to leave in?  By the way, some A-hole stole it last Tuesday and ripped the radio out . I recovered the truck and have a couple insurance bucks to devote to this project. It also needs bushings (Urethane all around--recommendations??) and tie rods so any advice there is truly appreciated.

 

Oh yeah, I need a daily  driver- I substitute teach your little darlings (dream job-lol).  Thank you everyone!!!

 

Tim

 

PS sorry no pix-- It ain;t a pretty sight!

Link to comment
  • Replies 42
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

I'm not a fan of poly-urethane bushings.  Good 'ol rubber is best for the street, in my book....  No squeeks, less harshness.

 

As far as the engine goes, they are pretty simple to begin with.  I'm not sure about the electronics "smog" on the rest of the truck,  but you can remove the smog pump and all the hoses to it (block them off on the other ends).  You can use the stock exhaust manifold (it's essesentially a 4-1 chamber design (decent), and aftermarket headers are built with low quality for these).  Just plug up the air injectors (picture below, but pictured is a different manifold, but same smog sh-t was on it).  It may be easier to plug the injectors rather than remove them.  Some people just cut and pinch them.   Make sure you don't disturb the PCV system, as this is a must for the engine....  Also pictured is a 1980 L20B stripped and sitting in a '71 510, just for reference of what the engine looks like without smog pump (that engine does have Weber carb and said "low quality" header on it)...

 

If your carb is running, leave it be.  If it dies, then consider a Weber 32/36 DGES ( http://www.webercarbsdirect.com/ ).   The reason I recommend that is; evey rebuilt carb I've gotten from a reputable company, has always had a worn throttle plate shaft.  That is the one part they don't usually rebuild, and yet it is the most important.  The Weber carb is a new carb, and thus lacks that issue.

 

You will probably get someone to tell you to just leave all the smog stuff alone as long as it is working.  Which isn't a bad idea, because it really doesn't work against you. But if your goal is to clean up the engine bay, then I fully understand. 

 

Gaskets are easily had at your local parts store.  I like the gaskets Felpro makes for this vehicle.  I especially like the Felpro gasket # MS22801 for the intake/exhaust gasket.

Your local parts stores, and local Nissan parts department will/should have everything you need...

 

I've had many a plugged catalytic converter.... easiest (not legal) way to fix it, is to remove it, and knock out the contents with a pry bar and bolt it back up.  Check with your local salvage yard to see if they will pay for the contents of the cat.  Some will pay over $50 for a used cat...

 

Have fun, and Welcome!

 

 

003.jpg

060.jpg

  • Like 1
Link to comment

I would suggest keeping it together, tune it up and get it running right first.  Just see if that's enough.

 

I think stock it's around 100hp when it's running it's best.  I would venture to guess taking that stuff off might not get you much more than 5%~8% increase, most likely less than that -- or -- no improvement at all, if you can't get it tuned right after taking that stuff off.  Personally I think in California these days it's best to keep it stock, but if that's not enough ... do a motor swap and work with the smog referee to keep the value and keep it legal.  Just my $0.02 here :blush:

 

I don't think you will even get 5% hp gain.  The only thing that will benefit power is removing the pump belt off the crank pulley... 1% gain maybe.  But I think he knows that.  Sounds like he just wants a less messy engine bay.

 

You make a great point, just because he is in a smog free area, doesn't mean the next guy will be...

Link to comment

a5b20fc6-bc06-41a4-80b1-4ddfe29bfb06_zps

 

Okay, I am getting this Photobucket thing dialed in. Tough getting the gray matter functioning after dealing with 9 year olds all day!  Anyway, here is the beauty, er, that would be my wife, next to the other beauty--the 1980 L20 720.  Also son and grandson - driving. Last (year) of the Mohicans (L20B). I took the heavy camper off, as well as the heavy bumper. I am going to check out a parts 1980 Long Bed rustbucket tomorrow for taillight, bench seat, spare tire, and who know's what else. The guy wants $200 or best offer. He sounds reasonable. The motor has low compression- barely limped home to its graveyard 6 months ago.

Humboldt protocol is: smog once, you are golden until you sell it.  Frankly, I have $650 into this puppy. I plan on holding onto it and using for daily driver.  Fun enters the equation. Drifting my son's rodded 510 on the grounds of my employer, a toity arts institution in SoCal in the year 2000, didn't exactly gain me employment security, let's say, but it was sure fun. I also owned a 69 Roadster, 100 foot repaint that was fun, but too short for my 6'00" frame.

Anyway, I want to strip the smog because the vacuum lines and the rest of that stuff is a ticking time bomb. Waiting to fail. And the cat is probably getting clogged.

I had a friend in Winston Salem who had a 620 with KA24. He called it a Honda smoker. I don't have those lofty aspirations, but another 10-15 smooth, clean burning horsepower and low rpm torquewould be cool.

 

Thanks everybody for your input! This truck won't be a concours vehicle! Rust happens here, and I have other $ consuming hobbies- mainly playing loud music on my guitar using old tube amps.

 

Sorry for the TMI.

BTW, son has Holley and intake adaptor.  Thoughts??

 

Cheers,

 

Tim

Link to comment

You said the truck wasn't pretty!! Now I'm embarrased for posting a pic of the 620!! :blush:

 

You won't see much Hp gain without spending $$.  You will be lucky if you even get 5hp with another carb, and if you do, it will be high up in the rpms. The intake manifold you already have is a good one.  Swapping the exhaust manifold may gain you a couple high rpm hp, but you may loose some low-end torque.  And, it's pretty difficult to find a round port exhaust header these days.  For mine, I used a square port header, and made the ports as round as possible...  I'd suggest driving it for what it is.   

 

Those rust streaks on your paint will come off with a Micro Fiber cloth and Meguires Fine-Cut Cleaner.

 

004-6.jpg

  • Like 1
Link to comment

10-2013007_zps3d51f6ce.jpg

10-2013010_zps008dcc27.jpg

10-2013006_zps8ac23ebc.jpg

 

Probably need a buffer for the Maguires?

Photo #2 = in case no one believes in rust here. This truck was from Ashland Oregon originally, so it escaped most of the wrath of rust.

Other photos = c'mon now, this stuff has got to be sucking major power.

Thanks!

Link to comment

The round upright canister has charcoal in it. When the engine is off any evaporating fuel in the tank or the carb finds it's way here and is stored. When the engine starts a vacuum signal open a valve and the fumes are drawn into the intake and burned. No power loss there.

 

The larger thin round thing is an air filter for the air pump. No power losses there.

 

The other thing with the two larger hoses is the air relief valve. It vents excessive pump air at high speeds. No power losses there.

 

 

You have to realize that most pollution controls are benign in operation and don't uses any power at all. The pump will use some very small amount, just pull the belt off. You won't be able to tell when driving or by your mileage if it's on or off.

 

The EGR is not on when the motor is cold, idling or at anything over 3/4 throttle. So people remove and nothing has changed performance wise. Anything over 3/4 throttle it's off.

  • Like 1
Link to comment

I am still figuring out how to "reply" . duh.  Good information about the pollution stuff. Somewhere in the continuum between "tear all that sh*t off!" and "leave as is" exists the sane approach. I just want the engine to breathe. Ironic? While ruining the air with pollutants?  Well, not if the old pollution stuff is leading this thing to bad performance and a trip to the wrecking yard.

 

BTW, my owner's manual says burn 91 octane. Do we?

 

Thanks again!

 

T

Link to comment
BTW, my owner's manual says burn 91 octane. Do we?

 

Mine runs better with premium (90 octane is what I have up here).  Making an assumption; Chances are you have a closed chambered head (W58).  Compression is between 8.5 and 9:1... Mike will be able to tell you off the top of his head...

 

This is a a great resource for identifying heads (below).  It's great info, but it states the W58 head doesn't flow well and is not good for high performance applications...  It may not be the best for high performance (especially the open chambered head), but I don't see any indications in design that merrit the statement that it doesn't flow well.  My 2 cents.  Your head is identified by the markings on the passenger side, forward of the engine markings, on the lower portion of the head.

http://www.davidcmurphy.com/olddat/html/tech/head_ID_2.htm

 

Here is another page from the same website that gives good info on the L series engines.

http://www.davidcmurphy.com/olddat/620tech2.htm#TS

Link to comment

The W58 heads should be open chamber. I've looked at all L20B '78-'80 W58 heads and they are the same part number. My theory is that in the 80s when a motor was out to be rebuilt, it was cheaper to import a low mileage one from Japan. These JDM motors probably had the closed chamber heads. This importing of motors explains the odd dual SU and intakes and the mystery long dogleg transmissions floating around over here.

Link to comment

That is a CLEAN truck.. I don't know why in the world Nissan put those mirrors on, as mine had them too, but other than that, that's a nice truck! I'd listen to Datzenmike about the smog stuff. I have a 720 bought at high altitude, and I have all the smog stuff EXCEPT the air pump and the BCDD(?). Maybe you could get rid of that, but the question is are you really gaining anything?

 

Speaking of high altitudes, maybe places like CO and KS were outfitted with the closed chamber heads for some reason? My truck has a W58 closed chamber head..?

 

If you want to do something to "hot rod" that truck as is, put on a nice muffler/tailpipe setup. I went to a 1.75" exhaust with an old school style turbo muffler from the cat back, and honestly, I doubt any amount of removing smog stuff would have added the power and gas mileage gains doing that brought me. Although these trucks have little engines, an exhaust upgrade made a noticeable difference. Just IMHO...

Link to comment

If you want to do something to "hot rod" that truck as is, put on a nice muffler/tailpipe setup. I went to a 1.75" exhaust with an old school style turbo muffler from the cat back, and honestly, I doubt any amount of removing smog stuff would have added the power and gas mileage gains doing that brought me. Although these trucks have little engines, an exhaust upgrade made a noticeable difference. Just IMHO...

 

I'm running 2" back to the muffler, and 1.75" after the muffler.  That works perfect for the 510.  1.75" all the way through would probably be better for the low-end torque needed to move the heavier truck off the line.

Link to comment

DSCN3581_zps18d78d29.jpg

DSCN3582_zps170d515c.jpg

DSCN3583_zpsa785f421.jpg

Well, the former owner told me it needed a new valve cover gasket. (Also said it needs king pins) So I switched it out with a new FelPro from NAPA.  I am thinking it might be leaking because of pressure generated by a glogged EGR, so that is next on the checkup. BTW I changed out the tranny and diffy fluids.  I am thinking the advice on changing exhaust as a first starting place sounds good.

The back kinda clunks around in sharp turns so I think it needs leaf spring bushings.

 

I got a spare tire from the Craigslist $200 parts rustbucket.  It has a dead L20B and (tempting) a 5 speed.

 

Cheers, and thanks for the feedback!

 

T

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.