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L16/18/20B street build need advice


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L16/18/20B best street build- advice needed.

I am NOT looking to create  a 200hp, fuel injected, or turbo motor with dreams or visions of winning ANY races.
My son and I just want to build a good, reliable, drivable, fun, spunky, MUCH IMPROVED VERSION, of this legendary 4 banger.
I already have all three types of engines (and then some), numerous intake manifold‘s, exhaust manifolds, blocks, and heads from every generation (up to ‘78) of L16/18/20B.
Lots of stock parts and pieces to choose from.
 I don’t mind shaving, shimming, porting,  polishing, or boring. And I wouldn’t mind bolting on a better carb, and better ignition. 
I don’t live in California, and I don’t believe that emissions are going to be a problem here in Texas! 
I am going to be rebuilding the engine anyway, so I might as well use all my parts and pieces, and do it right the first time.
This will be going into a 1977 620 pick up truck.
So guys, those are the facts! What do you have for me: the best recipe, your best build for streetabilaty and fun?
Thanks in advance! GP
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I would start with an L20B for the maximum displacement.


U67 head. I would un-shroud where the intake and exhaust valves come closest to the combustion chamber walls. This will allow air to enter and leave more freely. Scratch around the cylinder using the head gasket as a template and blend smoothly. Think of air horns or trumpets on side drafts used to smooth and increase the flow, only in reverse. This is somewhat what I mean but is for a 39mm gasket and used on a Z24 block so is a bit larger than what you need to do. Removing the shrouding will lower the compression slightly but the gains are worth it and you can always slice 0.020" off the gasket surface, that's almost 3cc per combustion chamber volume removed to compensate.



For the ports not much to do as they are excellent to begin with. Remove any casting flash is all that's needed.


Definitely port match the head and the manifolds to the gasket. Use the gasket to scratch the outlines and grind away, smoothing inwards for a inch or more. This aligns the intake and exhaust ports with the manifolds and removes any lip. It's a small thing but many small things add up and these two never go out of tune and are there forever.


I think 280z or 280zx larger diameter valves and seats will fit. Check that they are the newer hardened steel ones.


It's the cam that makes power, but the more power the less driveable it is. Depends on what you use for carburetor(s)



L16 or L18 intake ('78-'80 L20B intake is larger but only if you can find one) that uses the coolant passages and drill two 3/8 holes in the U67 head to convert for use. An L16/18  by pass tube to make everything work. The '75-'77 L20B intakes and exhaust manifolds bolt together and are crap.


L16 exhaust 4 into 2 manifold with 2 into one down pipe. There are early good ones and later bad ones. Get the earlier with separate discrete pipes like the one on the left. 1 and 4 and 2 and 3 have their own pipe. This separates each exhaust pulse as far away from the next. The one on the right just dumps them together with two outlets. Probably cheaper to make.




A 32/36 Weber is good for some power. Best of all it's reasonable and not too crazy. Expect $300 Redline Weber from Pierce Manifolds. There are a lot of fakes and counterfeits out there so go to Pierce manifolds for it. Comes with adapter plates, hardware, air filter.... everything needed.

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Super! I've got the L20B and the U67, and I believe that I have the exhaust manifold that you show on the left side, I probably have the intake as well - need to check.

Will do with the porting and polishing. I have a single Webber sitting around (used) so I'll need to check and see what it is. I have the 280 and 280zx valves.

Camshaft? I have several... from the following cars 610,620,and710. So... what to do with the cam if my Webber turns out to be the correct one?

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The L20B cams are all basically the same. I meant an after market cam. Something with a little more lift and duration but reasonable. Better to have small cam and want bigger than to have a big cam and wish it were smaller. This also applies to carburetors.

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I have U67, A87, “210“, W58, and N58 heads 


I also have some 710 and 610 camshafts, and one mystery camshaft very carefully wrapped and marked:

“ ISKY”😃🙏 ... however, I know nothing about these camshafts, whether they have been reworked, or if they are any good at all; I guess I’ll leave that to the machine shop, and I suppose they will be able to tell me the lift and duration...?


but, with an L20B, and a cleaned up U67 head and intake, and a 32/36 Weber, what should I be shooting for on my cam? BTW... what do you think about a slightly oversized bore on the block?

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If reboring, a good idea if rebuilding it rather than a $50 'hone and ring job,' might as well go to the max 1mm (0.040") over. Adds about 46cc or 0.023% more power/displacement... not really measurable. The L20B is 1,951cc so this brings it up to 1,997cc, a true 2 liter engine.


Look on the ends of the Iskendrian cam for any numbers or letters. They don't grind them and not ID them.






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34 minutes ago, datzenmike said:

If reboring, a good idea if rebuilding it rather than a $50 'hone and ring job,' might as well go to the max 1mm (0.040") over. Adds about 46cc or 0.023% more power/displacement... not really measurable. The L20B is 1,951cc so this brings it up to 1,997cc, a true 2 liter engine.


Look on the ends of the Iskendrian cam for any numbers or letters. They don't grind them and not ID them.






Ok, I’ll go check it out...

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The original sock cam was probably L16 and then reground. Post a picture. The L20b cam is different. Doesn't matter it will work in any L4 engine.


0.480" lift and maybe 287 duration. 0.480" lift is very close to 'stacking' the valve springs.

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Found this...  https://zcardepot.com/products/copy-of-camshaft-comp-cam-racing-280s-l16-l18-l20b-510#


Isky L480 camshaft for Datsun 4-cylinder L16, L18 and L20B engines. Good street/race cam. Upgrade over stock.  

.480" intake and exhaust valve lift

280 advertised duration on intake and exhaust

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I would say your fine on the springs  480is close to stacking but just put one on and see. a machinist can cut down the seat area 5-20 thou if worried.

I would get the Isky springs and only use one of your stock one and one of the aftermarket. inner or outer   depends which one you want.  but youll not need to overload the cam on just a daily driver stock motor.


a place in australia has cool lash pads that use the stock reatainers  so they dont pop out.  if you know the size you need.  If you can take a photo of the cam close up we can see if its new or a reground

http://www.precisionshims.com.au/products/slotted  the recessed shims on the bottom!!!!!!

Edited by banzai510(hainz)
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I’ve got some good pictures, and I would love to post them;


but I am so embarrassed and feel like such a retard;


... I’m going to need a few tips on how to get these photos from my “photos“ program on my iPhone over into this forum...



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The lash pads are select fit. Unlikely they will all be the same.


I would run a generic L20B cam to start and break in and tune up. Get it all working then change the cam. This way any problems... you know it's the cam.

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Yes, I will definitely use the L20B block, but I would like to get the most performance that I can, and yet still run pump gas, and not be frustrated with the car dying in traffic.


I have all these various heads, the Weber carb, and the good intake and exhaust manifolds; the Isky cam etc...


...so with all these parts at my fingertips, and a little bit of wisdom from guys who have gone before me, I would like to do the best job that I can...


 I have the U67, A87, 210, W58 & N58 heads. Datzunmike suggested the U67-I was moving in that direction.


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210 FORGET this one. Used on the L16 but may have been designed for the L13 or L14. Too small valves, ports and smallest combustion chamber 38.5cc of all L series.


A87 has smaller ports and some have a smaller intake. Open combustion chamber 45.2cc (some imported ones are closed 41cc, but still larger than the 210)


W58 and N58 are open combustion chamber 45.2cc, basically the same as U67 45.2cc, but with round exhaust ports that have steel liners for emission control. Round or square exhaust manifolds will work on them but L16s are the best. I did find an imported closed chamber 41cc W58 head once.



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