STAGE ONE: Engine 101

[HOGIE]

Hello Ratsun Nation,

As my profile says I am a newbie. I've always had a thing for since my dad let me barrow is little toyota when I was 20. Now I finally got my self a REAL truck, my first Datsun is a 78' 620 king cab. Its rough and need love.

 

I start now trying to assess what I have. Via the tag inside the drivers side door I know that the body is a 78' but I'm not sure if the this is the correct year motor as the previous owner said that they found this body and swapped motors.

 

My question is how do you ID a L-series block to tell if it is a L20 vs L-something else? Is there a marker on the block? And one more step please help me and tell me what I have.

 

Thanks, HOGIE.

[72240z]

Its stamped on the block on the passenger side I believe right by the oil dip stick. The head is as well. 
You can see it in this pic.

[HOGIE]

Thanks for the info. Hope my motor will look that clean soon.

 

 

Here is the pics of the motor and carb setup. Does this look like the correct stock stetup for a 78' or could it be a different vintage? Looks rough, I know.

 

[datzenmike]

See that hose coming out of the intake just below the front of the carb? It should be connected to the hose near the thermostat housing.

 

The intake isn't a '78 as it does not have any EGR valve on it. L16 or L18 intake.

 

The exhaust looks like a '78 or newer and the EGR tube is plugged. If so it is a round port exhaust used on a W58 L20B head.... well usually.

 

Has a '79 or '80 distributor on it.

 

Does not have the L20B fuel rail with return line.

 

This is a mixture of engine parts.

 

 

 

Look on the top edge of the block where the head meets it just behind the dip stick. The engine size is stamped there. Use wire brush if needed. L16, L18 L20B

 

Look on bottom edge of head between #1 and #2 spark plugs to identify the head used. Could be 210, A87, U67 or W58

[HOGIE]

Block is a L20B serial 049413 and the head is a W58.

[datzenmike]

Block is a L20B serial 049413 and the head is a W58.

 

Interesting. Used on '78 and up vehicles.

 

Vacuum advance hose on distributor is off.

[HOGIE]

I need to find some clear picture of what the setup should look like. I purchased a Haneys manuel for these models but the diagrams are not very clear.  I want to eliminate as much as i can to keep the engine simple. I also have a L16 block that has a W53 head on it. thinking of just switching over to that. Good or bad idea? I know that the L20 is spect for higher horse power. Any opinions?

[DanielC]

2000 CC's or 1600 CC's.  What do you think had the potential to make more power?

This is the quickest way to identify a L-20 -B engine.

See the two bolts heads close together between the distributor base, and the water pump with a little too much blue silicone?  These bolts are unique to the L-20 -B because the block is taller, to accommodate the longer stroke of the L-20-B.  Other four cylinder L-engines only have one bolt here.

 

If you look at the front of the side view picture several post above, you can also see these two bolts between the water outlet on the engine, and below the fuel pump mount.

[banzai510(hainz)]

L20 and youinstall a L16?

 

this would be like you producing a Porno movie and bring n in a guy with a small er wiener.

 

clutch sizes issues.

 

whats wrong with this motor.?????????????just clean up the motor with some simple green and hand cleaner.

[racerx]

First do a compression check on motor..if reading is okay then proceed with cleaning it up.  L20B will make easily make 20 more HP than L16.  Do a lot of thinking and asking before you start taking things apart.  As they say, Measure 3 times and cut once not cut 3 times and measure once.  The good ting is that there are a lot of people on this site that knows their stuff.  Good luck....

[72240z]

I think the saying is "Measure twice, cut once". If a person fucked up 3 times because they measured wrong once I think they should just put the saw down and walk away lmao

[bonvo]

if i remember right Eugene is relatively close to me what issues are you having with it? if you can get it here i could help but im sure there are other datto heads closer

[HOGIE]

Thanks. Clearly the consensus so far is the L20 is the way to go, if its fit to run.

[HOGIE]

Is the L20B fuel rail with return line the steel tubes that are running back to the fuel pump in the picture that Daniel posted of the L20 engine? I think I found a correct intake in Corvallis.

[datsunaholic]

I wouldn't change the intake; I'm not entirely sure what you have since the PCV faces rearward, it's not a L16/L18 one, but no EGR makes no sense since all L20B one shad an EGR.  It could be plated off.  Pic it too small to see any detail.  But if you got the correct intake (and you'd have to use a 78-80 L20B intake) you would need to reconnect most of the emissions system, which is all missing in the pics.  Or plate off the EGR.  Unless you're in a smog testing area I'd avoid this as finding working components can get difficult.

 

Carb is an L16 or L18 carb.  It'll work, but not optimally.  It also has an L16/L18 fuel pump, which is probably the only way it avoided constantly flooding with the fuel return rail gone.

 

Your biggest issue is the plugged off hoses and haphazard removal of hard lines, which has left a snake den of disconnected equipment.  It's definitely a hodgepodge of parts.

[datsunaholic]

This should give you an idea of how much is missing (this is a '78 510 Wagon, but the engine and emissions systems were the same):

 

[HOGIE]

So does finding a correct carb, intake, fuel pump and fuel rail make much sense? I believe I've already located these parts. Doing away with unessesary EGR crap sounds good to me. The L16 motor has a 5-speed trans hooked up to it, will this bult right up to the L20? Does any one out there need the L16 block and head?

[datzenmike]

The L16 motor has a 5-speed trans hooked up to it, will this bult right up to the L20?

 

Any L series transmission will bolt to any other L series motor. But there's more to it than that. For one the two most common L 5 speeds are different lengths. If you have the short, your truck driveshaft will need to be lengthened. Additionally, the L16s only had 200mm clutches and your truck will have a 225mm one. You will have to swap the L20B release bearing over to use it.

[HOGIE]

Here is the current news:

GOOD:

L16 in my parts truck has good compression, ~165 across all 4, and a 5speed.

 

BAD:

L20b currently in the truck has compression of 150, 60, 150, 90 for 1,2,3,4, respectively.

 

PLAN:

-Pull the motor/tranny from parts truck. 

-Check out the 5speed, if good I'll get the driveline length changed, if needed, and run it for now.

-If the 5speed looks rough, run the 4speed with L16.

-Pull head/oil-pan, remove pistons and check tapper of cylinders.

-Based on state of cylinders procceed with appropriate rebuild.

-Eventually reinstall L20b.

 

Any comments?

 

I do have some concerns about a choke setup for the L16, wire harness differences, driveline length differences, and clutch differences like what Mike metioned before.  

[racerx]

will you have elect. choke or manual choke for carb?  will you also go to weber 32/36?

[HOGIE]

I will likely run the late model stock carb that is on the truck now with the L16, it already has a rigged up manual choke but its janky. When all is said and done I'm not sure if I will run the stock L20 carb or convert to Weber. I kind of want to stay stock besides removing emision stuff and use the electric-automatically-choked carb.

 

Although I like to here comments and opinions that I can build off.

[racerx]

good idea to keep stock carb.  Save your money for somtin else.  Those stock carbs are actually pretty good.  There are some here that will only run stock carbs..then if need be put a 32/36 weber.  BTW be careful about buying weber make sure it's the real deal, none of that IMPI clone, looks just like webers but made in China.  Heard and read too many bad QC issue about those carbs.

[Xnke]

Don't pull that engine yet.

 

Does it start and run? If Yes, go to next step.

 

Run until fully warmed up. If overheats, fix the overheating problem first.

 

Engine fully up to operating temperature. DO VALVE ADJUSTMENT.

 

NOW do a compression test. All plugs out, throttle wide open.

 

if the same two cylinders are low, shoot a teaspoon or so of oil in the chamber and do a wet test...if they come up, you need rings.

 

Retorque your headbolts after the engine cools down. One at a time, using the correct pattern, and yes, you must use a torque wrench.

 

Don't count that L20B out yet.

[HOGIE]

Can anyone help me identify this carb?

[racerx]

looks like a 32/36 weber a/ auto choke.  You can also call weber direct and tell them numbers stamped on Carb.. Are you trying to install in a Datsun.. You'll need an adapter plate..like I said get in touch of weber direct...ask their tech dept.  they should be able to tell you the detals.  Not sure how long that's been sitting, may want to freshen it up a bit. Good luck.