L20B building -- 1978 A10

[Xiao_Hu]

So I got to carb on order to replace my bad carburetor. In terms of overall readiness for the main drivetrain I just need to figure out what parts I should purchase to improve my car further. 

 

I have a friend who has a 1971 wagon and among his parts he has a 210 casting head for an L16, which supposedly has a smaller chamber compared to my W58 head on my L20B. He has offered to sell this head to me because he has an A87 head on his car. 

 

Am I getting a better head overall or am I asking for trouble? 

 

I'm not necessarily going to replace the head right away but I am interested in acquiring the head, and keep getting in reserved for when I pull the engine and transmission to replace the transmission with a 4-speed (it currently has a 3 speed automagic but the car was already set up for manual transmission and has hack modifications so I want to return it to a better config on a budget)

 

I will check to see if the head has been reworked though before I put a value on it. 

[datzenmike]

The 210 or 'number head' is a poor choice for the L20B which all have 'letter heads,' U67, A87 and W58. It has smaller ports and valves so it won't flow enough for the 2 liter engine. Your W58 head is fine as is. The combustion chamber is smaller and compression would be just under 9.25. They only really work on the tiny L16 engine and only of any value to someone who has one.

[Xiao_Hu]

Ok, that makes sense. I'll pass

[datzenmike]

Back in the '70s I did put a 210 head from a 510 on my L20B that was in a 521 truck while it was out being milled down. I noticed absolutely no difference even though the compression was well over 9 to one. Gas was much better back then. Wasn't expecting any change good or bad, in fact at the time I didn't even know the heads were different so didn't look for any changes. It was only a week.

 

The 210 head will work for a temporary but they are worth less than zero.

[Xiao_Hu]

Gotcha. Can you get new heads for the 4 cylinder L series? Some guy on FB was insisting to me you can get new heads from a variety of places. 

[datzenmike]

First you would need a reason for replacing what you have. You have a W58 so at worst it can be rebuilt with new seats, valves, valve guides, seals and perhaps if needed, the face milled to flatten it.

[Xiao_Hu]

From what I understand, I have the least desirable head released for the L20B as it has the lowest compression ratio because the chamber is open. My friend's 1971 510 has an A87 head and from what I understand that's one of the more desirable ones. I have very little interest in going forced induction or EFI. I would like to however have the engine produce the most power and breathe the best possible so I would like to ideally acquire a good set of parts for cheap. That's why I asked about the 210 head because my friend has it as a spare. It was the original head that was on his vehicle. 

 

I'm not really wanting to pull the entire engine and do a bottom end swap to change the type of piston or anything else like that. I'm all about doing things cheap, I had an opportunity to score a cheap head, I didn't know if it would be an upgrade or not. The fact of the w58 also has steel lined ports like the N47 L28 head gives me pause because I've read that those can be very problematic. 

[datzenmike]

ALL L20B heads are open chamber W58, U67 and A87 are all the same compression about 8.4 to 1. There are closed chamber W58s and A87 but not U67s and these are hard to find. They came here on Japanese import engines. No way they came on our L20Bs as emissions standards are very strict. A low mileage head from an import engine was way cheaper than rebuilding one. Naturally some if not most were sometimes closed chamber. A closed chamber head on an L20B made 8.9 to 1 compression.

 

The earliest A87 was on the '73 L18 in the 610 and 710 cars. The next year the 610 engine was upgraded to the new L20B but the A-87 was kept that year. The 710 and the 620 continued through '74 with the A-87 and switched to the L20B and U67 heads in '75

From '75-'77 the 610, 710, 620 used the U-67 head.

From '78-'79 the U-67 was used in the A10 and for '80 switched to the Z20 engine.

First use of the W-58 was in the '77-'79 S10 200sx

From '78-'79 the W-58 was used in the 620 truck

The 1980 720 truck was the last year the L20B and the W-58 head was used.

 

 

 

The W58 and the U67 are basically the same head but for three things. The W58 exhaust ports are round, (all other L heads are rectangle shape, the only L20B head to do so. Inside the round port is a thin steel liner. This liner is held away from the port walls by small bumps cast into them. This will allow the hot exhaust to heat them to glowing hot and this plus the added air injection will complete the combustion process on any unburned gases. The W59, like all other L series heads other than the U-67 has to small holes that allow coolant to transfer into the intake below the runners. This coolant is collected by the thermostat by pass tube are recirculated back into the engine. The coolant warms the intake in the winter and draws away heat in the summer. You've noticed how hot the intake gets with the 600F exhaust manifold just a 1/2" away.  

 

Now if you were going to race this, or upgrading the cam to make more power, when I would suggest removing them, otherwise you'll never know the difference.