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1980 L20B Newbie


Humboldt

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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

 

The last king pin truck was '77.

 

I think you mean clogged PCV valve. Pressure still shouldn't build as the hose on the valve cover would still be open. The PCV is on the intake below the carb on the driver's side. There is a larg hose from it to the side of the block. Pull the hose off at the PCV and start motor. If you hear a hissing sound it's working.

 

Just to be sure... the transmission uses GL4 (NOT GL5) 80W90 oil. GL5 must not be used in the transmission unless the container says 'yellow metal safe' or 'safe to use on brass synchros'. GL5 80w90 is only for the differential.

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Thanks Datzenmike.  I did use GL5 in the tranny.  Oops!.  I will replace with GL4.  Do I need to flush the GL5 out in any way (other than draining it) prior to refilling with GL4?  Do you think it did any damage over 2 weeks?

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No it's a long term thing. Just change sooner than later. GL4 has the same additive that eats the copper alloy rings but at a safe level, GL5 has it in 50% higher concentration. There is no copper alloys in the differential.  

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mailto:hjjpm-4059704983@sale.craigslist.org?subject=1980%20Datsun%20Truck%20for%20parts%20-%20%24200%20%28McKinleyville%29&body=%0A%0Ahttp%3A%2F%2Fhumboldt.craigslist.org%2Fcto%2F4059704983.html%0A

It is on Craigslist humboldt

 

It is on Craigslist Humboldt. The owner, Jeff, said that it gradually pooped out then he limped it to its final resting place in McKinleyville, where I saw it.  He thinks it lost compression. I didn't buy it, although the 5 speed would be nice.  If you buy it to pull the engine (L20B) and don't want the 5 speed let me know and we can wheel and deal.

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I checked the PVC  by sticking my thumb over it, and it had suction. I am taking it in on Wednesday to get the cat out, which I will keep. Also getting it lubed for $12 because it saves the effort of popping off those rubber caps and putting zirc fittings in. They are going to check tie rods and other suspension slop.

 

The clutch has some "judder" that I am living with for now, and the previous owner put fatter tires on the back. Ultimately I will get some nice skinny matching tires all around.

 

If I scabbed the 5 speed from the parts (long bed) would I need a shortened drive shaft?

 

This truck is becoming cooler by the minute!

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That's what I needed to know, Thanks!

BTW, I see that the long bed has a 4.111 dif, compared to 3.889 for the short bed. If I kept my 3.889 with a 5 speed instead of the 4 speed would that mean higher top speed (which I am not necessarily looking for) or lower?

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Yes only the '80 long bed and Cab Chassis came with the 4.11. The long bed also only came with a 5 speed.

 

Both the 4 and 5 speeds had the same gears 1 through 4th. Fifth is an overdrive and will slightly lower highway cruise RPMs but fourth gear is almost always faster than fifth.

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does the higher 4.11 raise the top speed (for both 4 and 5 speed)? Putting it another way, If the first 4 gears are the same, what would the effect be of putting the 4.11 on a 4 speed?  Zippier through the gears but lower top speed, or the other way around.

 

Presumably, the rationale for using the 4.11 would cbe to compensate for the overdrive and have the best of both worlds--higher top speed, albeit reduced from what the 3.88 would have given, and zippier accelleration through the gears. 

 

This is probably automotive 101 stuff, but I appreciate the remedial

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  • 2 years later...

Hey Gradyfest,

 

Yeah, I'm still driving it. The idle has returned to being high and I haven't had time to check if it is sticky cable, carbs, or what. It runs fine but runs on when I shut it off. I see that you have a 1980 long bed.  Cool--better ergonomics for legroom and five speed, right? Let me know if you need any parts I salvaged from a 1980 king. Not too many--my son gets the 5 speed--but dashboard stuff and miscellaneous. I have a weber I am waiting to throw into my goon dormant project. I am tempted to throw it into the 720. Here in Humboldt once smogged is good. So if I hold onto it I can do mods. Humboldt is the wild west. Where are you in Cali? cheers

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Sound like something's sticking.

 

No, mine's a regular cab and a four speed, so no more leg room and I keep it at or below 55mph with no overdrive. The long bed is nice for hauling bigger loads and makes my frame and truck over all longer and a little more stable I guess, about it. It does look better being long since it sits higher being a 4x4 I suppose, matches.

 

What colors are the parts truck? 4x4?

 

 

Cheers!

 

 

Never made it up that far, I'm in Orange County.

 

 

If you want to see my truck you can find my thread about it off my profile. It's in this 720 section as well.

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