Multiple L20B’s street build

[Gp620Rat]

Multiple L20B ‘s

  Street builds. Advice.

 

Looking for  advice on the best combinations for the various blocks,  heads,  cams, etc. that I have. 

 

I actually started this conversation about a year and a half ago, and got great advice from Datzunmike, Stoffregen  and a couple of other smart builders, but then (sadly) got called away on family matters, and now I’m back at it. 

 

I will try to include the good advice that I was previously given. I have a much better and more complete inventory to share in THIS post.

 

Previously, I didn’t ASK much about the various blocks that I have, and which ones would be best. I have six L20B’s, and one L18.  But I have a “variety” of different L20B blocks.

Listed below ⬇️.

 

A number of the heads that I have, have the old bronze valve inserts, and since they will need to be pulled, and replaced with the sintered iron inserts, I thought I might ASK about upgrading to the larger 280ZX valves. ? Is that a “thing”? Can you do it? Is it worth it? Is it worth it if I don’t use a new upgraded cam?

 

You’re probably wondering why I have all of these engines; and why I’m going to the trouble of restoring them. 

 

I have all of these Datsun  four-cylinder engines, plus a bunch of six-cylinder engines and a variety Z cars, that I bought, all in one giant batch. It was a bit unexpected. I have driven a 280ZX 10th anniversary edition for many years so… I couldn’t pass it up.

 

The main reason for restoring all of the 4 cylinder engines is that I really want to LEARN how to do it=EDUCATION (to be applied to the 6 cylinders next).  So, I’m planning to restore them (4cyl) and sell them. I will keep one for my ‘77 620 pick up.  

 

(I’m an “ok” mechanic, looking to improve and specialize in The L-series engine.)

 

I will then have the proper knowledge tools, processes, machine shops, lingo.
 

You guys have a fantastic knowledge base, plus I am reading Tom Monroe’s Datsun rebuild book along with Frank Honsowetz’s modify your Datsunn engine book…together with the FSM.

 

I don’t know much about the 510/ vintage racing world; but I do know that they have certain things that they are looking for, and certain things that they are trying to avoid. I don’t want to butcher these parts.

 

I would like to restore these engines in a manner that they would be desirable to someone after I am finished. 

 

I don’t want to go  crazy with way over-boring them, or stroking them or anything too wild… Just good solid, peppy, streetable engines, that would also be of some interest to the 510 or vintage crowd. 

 

With the exception of the one engine installed in my truck, they are all on little dollies , in various states of assembly or disassembly. (that’s how they came to me. )All in very good shape actually. 

 

My plan is to break them all down, and get them vatted, magna-fluxed, and “at a minimum” honed, or bored, to be able to start with a very stable and predictable platform.

 

Below, when you start adding up how many engines can be built and completed -the numbers don’t add up. There will be extra parts, and fewer complete engines. No problem. It will all get used, and or sold.

 

Here are theingredients⬇️: 

BLOCKS:

5 - U95 L20B blocks

1 - U67 L20B block

1 - N56 L18 block

Best block?

 

HEADS:

4-U67 heads 

Ex=35/I=42

 

4-A87 heads 

Ex=35/I=42

 

1-W58 head

E=35/I=42

 

1-N58 exhaust inserts round 

E=35/I=42

 

3-210 heads

 Ex=33mm/I=38mm

(port matched, ported, polished - still small valves- un shrouded)nice mod work on 2 of these.

 

CAMSHAFTS:

1-1976 610

1-1976 610

1-1976 710

1-Isky L-480

3-unknown (installed)

 

INTAKE Manifolds:

4-A46

1-A35

1-230

1-dual carb intake 

1-K25 emission end=large 

1-N58 emission end=med 

1-U67 emission end=small

    ⬆️Delete plates

 

CARBURETORS:

1-32/36 Weber

4-stock Hitachi?

 

EXHAUST Manifolds:

3-good old non emissions 

3-newer emissions

 

I will definitely start with the 

U67 heads,un-shrouded, and port matched. Together with L20B block. And with the old non-emissions intake and exhaust manifolds-again all port matched.

I will start with the stock, cam, to get everything smoothed out/ stabilized; and then move to the Isky, or other performance cam.

 

If I am restoring them -to sell them- should I bother with paying the price for upgraded street cams? Will I be able to get my money back out of them, when I go to sell them?

 

Since I have most of these parts and pieces already available to me, I don’t mind paying a little bit for the machine shop, bore, and possibly for an upgraded cam; but only if I can get the money back out when I go to sell the motor… does that make sense?

 

A number of these heads that I have, have already had nice un-shrouding work done, and a little polishing…

so I have some upgraded heads, with stock valves, 

that will go on L20B motors…

should I buy the upgraded cams? 

DEFINITELY NEED ADVICE HERE. 
 

I haven’t searched/priced the performance cams yet… nor have I priced what this type of motor would sell for when I’m finally finished with it…? 

 

Your thoughts and suggestions.

[Gp620Rat]

One thing I forgot to mention, was that I would like to build these engines, without any of the emissions stuff; just to simplify the engines, and not have to chase down parts for the emissions system…

[Duncan]

I don't think I'm alone on this, but if I was looking for an engine to put into one of my cars, I'm very leery of buying one that has been built and assembled by someone else.  I'm sure most of the sellers have good intentions, but if I'm forking out money, I'd much rather spend it for a build done by myself and I know exactly what's been done, and by who. I would only buy a motor that was done (or mostly done) from someone I know well, or possibly that has a lot of references.

 

If you wanted to move all those motors, it doesn't make sense to me to build them all.  A lot of work and dollars to build them all, and you would probably couldn't sell them for what you have in them. 

 

I just sold a completely refurbished seat with new upholstery, new foam, padding, and the bare frame and springs completely cleaned and painted for a 620 pickup.  It was never installed after it was done.  It took me three weeks just to get $200 for it.  I broke even on the seat cost and materials, and got zero for my labor.

 

Anyway, just my opinion, but rebuilding three engines is going to cost you a lot of cash and time.  I would do one for my car and figure out how much I have in the rest and price the pieces from there and see what happens.

 

Either way, good luck on your project.

 

 

 

 

 

 

[Gp620Rat]

Yes, you are correct. Point well taken.

 

One of my main reasons for doing this, is the education.

 

I really, sincerely want to get into these engines, and then move onto the six cylinder engines.

 

I’m not too terribly concerned about making a killing ($) on these things when I’m finished… I just want the experience;

and the experience from this forum and group of builders, who have been deep into this L20B world for much longer than I have…

[Gp620Rat]

As for not wanting to put an engine into your car that someone else built; I completely understand that… I would not sell any of these engines to anyone if they did not run properly. My plan is to put each engine into my truck and drive it, and prove it. Document it… video, receipts, photos.

Good thoughts…thanks.

 

[datzenmike]

 

 

 

5 - U95 L20B blocks

1 - U67 L20B block

1 - N56 L18 block

Best block?

 

Any L20B is fine because larger displacement. They don't have to work as hard as an L18.

U60 were the earliest ('74) U67 '75-'76, U95 '77 and on. Only difference is the age.

N56 I don't know this one. L18s used K25 and A87 blocks?

 

 

 

INTAKE Manifolds:

4-A46

1-A35

1-230

1-dual carb intake 

1-K25 emission end=large 

1-N58 emission end=med 

1-U67 emission end=small

 

They will all interchange. L16/18 have smaller ports and L20B the larger. '75-'77 L20B U67 heads have intakes that bolt to the exhaust manifold so it's hard the separate for a header. Also the warming of the intake by exhaust heat is not good for performance. The '78-'80 L20B intakes were large and circulated coolant from the head to warm it in the winter and draw away radiant heat from the hot exhaust manifold in the summer. L16s don't have EGR valves on them. All L20B intakes have some form of EGR. Earlier I put a '79 intake on my U67 head by drilling two 3/8" holes and a '79 by pass line to circulate the coolant. I like the coolant exiting the head on the sides to reduce any 'hot spots', rather that having to travel all the way to the thermostat. 

 

Dual carb are from L16SSS and L18SSS and mount 38mm Hitachi SUs to them.  These will work very well on an L20B and give a little more power when revved up. My SU intake is a K14 and there is at least one other number.

 

 

HEADS

210s were for the L16. Valves and ports too small even for an L16. I heard this head was designed for the L14 but used on the L16.

 

A87s were much improved and some are closed chamber. Some A87s have smaller intake valves

U67 Large ports than the A87 and valves.

W58 same as the U67 but has round exhaust ports rather than rectangular. The ports also have metal liners that heat up and help burn away emissions. They would need removal for performance. I have a U67 and the intakes look yellowish, like they are made of bronze. Phosphor Bronze or Beryllium Copper were two very hard alloys. I don't know what the original pre '72 soft seats were made of. It was the leaded gas that lubricated them. GM switched over to induction hardened steel seats in '73, Nissan???

 

 

 

 

[Gp620Rat]

Datzunmike, thanks for the good info on the engine blocks. The N56 has the L18 stamp on it. it’s good to know that there are no big crazy differences in the L20 blocks.
 

The intakes: ok, all interchangeable. I will port match everything. If I am going to delete the emissions stuff from the newish intakes, can I just create a delete plate for the exterior end?

 

I see where the 3/8 inch holes come in for the U67 Head, but could you explain a little bit more about the bypass line? Slightly more detail.

 

I believe that I have an A87SSS head that has had quite a bit of nice work done to it. A87SSS does that make sense? SSS means what? I have the dual carb manifold, just no dual carbs.

 

All of my A87 heads have 35/42mm valves.

 

what do you think about the bronze valve seats? Keep going with them, or have them replaced with sintered iron?

 

correct me if I’m wrong, but all of the port matching, and un-shrouding ,   are just efficiency gains, slight power/tuning gains, that are successful with or without an upgraded performance cam? If I go with the performance cam later, all of this good head work really becomes essential.?

 

what kind of a performance cam would you recommend? And do you know of some folks on the forum that are selling these used or new? General price? Also, I probably need at least one more exhaust manifold or headers if someone is trying to clean out the garage and get rid of them.

 

once again, thanks for all the great information! I’m definitely studying every word.

GP

 

 

 

 

 

[iceman510]

Been awhile since I actively had any head work done, but getting ready to soon again.

 

The engine types to be concerned about seat wear without lead additives in gas were typically cast iron heads with no separate valve seats.  Datsun Aluminum heads have seats that should be fine.  When I have had machining done previously, no one ever said I needed to replace them unless they were worn out.  I think the machinist said they were steel seats.  I have an A87 head I will be getting a valve job and a check of the guides here soon.  I will ask him about the seat material.  He just did my L16 block conversion to L18 bore size to put 85mm pistons in.

 

Are the cams all from L20Bs also?  Do they say U20 on them?  That is the SSS grind and a decent street cam.  If you want to do something else with them, you can have them reground.  I just sent one to Delta Cams in Tacoma, and because it was a bit rusted and pitted, they will regrind it to a slightly more aggressive profile for only $100.

 

Is the L18 a short block?  If you want to concentrate on the L20Bs, I would possibly be interested in it as is.  Depending where you are in TX I could potentially pick it up as I get there occasionally in the southeast Houston area.  Also could be interested in an A87 head, particularly if closed chamber (peanut).  I don't think you specified that.

[Gp620Rat]

Also, would you bore any of these engines? If they didn’t need it? They are going to the machine shop, and they can either be honed, or they can be bored. I don’t want to de-value the engine for someone else who might be interested later. Also, if  you were to bore the block, at what point are we talking new pistons?

[iceman510]

An A87 head is not necessarily an SSS head.  The SSS package was slightly higher performance package originally available in Japan on the 510.  Better cam grind, closed chamber head, dual Hitachi SU carbs, etc.  Some of those parts and the nomenclature made it over here.  A87 heads seem to have come with differing valve sizes.  Your 42/35 is a good combo.

[iceman510]

2 minutes ago, Gp620Rat said:

Also, would you bore any of these engines? If they didn’t need it? They are going to the machine shop, and they can either be honed, or they can be bored. I don’t want to de-value the engine for someone else who might be interested later. Also, if  you were to bore the block, at what point are we talking new pistons?

 

Not necessarily for a rebuild, only do as needed.  Any overbore needs pistons to go up in size.  If someone is planning to use for racing in a class with requirements, too much overbore is not desirable.  For street, no big deal.

[Gp620Rat]

Iceman, thanks for the great information. I will need to look at my cams to see if any of them have that U20 stamp or engraving. Currently, they are wrapped in newspaper, and there is mention of the SSS on the newspaper. I will look at the other cams as well. I have a number of other parts that indicate that they came from the SSS combination that you mentioned. This is the great kind of information that I can’t seem to find anywhere else.
 

The L18 is the only engine that I got in this batch, that looks as though it has already been to the machine shop. I will need to check, but I believe it has 85 mm bore. it is a short block. Most everything I have is disassembled. I have two engines that are assembled.

 

I have an A87 head that has had quite a bit of work done to it, and has RallySport lightly engraved.

 

 

[datzenmike]

SSS heads were on the Japanese only 510 Coupe and were marked 219 though in rare circumstances it may also say A87. The intake ports give it away as they are 1.5" or 38mm and will match the 1.5" dual SU carburetor intake. No other L series intake port is this large. 219 heads are always closed chamber and used on the L16/18SSS engines that had flat top pistons they produced a tasty compression increase. If a 219 head is used on an L18 or L20B here the compression goes up a bit but the piston tops all have a dish so the full advantage of the large quench area is somewhat lost.

 

The SSS cam is almost identical to the stock L20B cam with 0.413 lift and duration of 248 degrees. Here I must say that 280 is likely actual true duration where as modern cam grinders make the measurement universally at 0.050" lift. This would drop the 248 well down, what to I don't know.

[Gp620Rat]

Yes, mine is an A87, but it absolutely has those massive 38mm intakes, that are perfectly formed and smooth.

 

I was wondering how some guy in his garage with a grinder got them that perfectly round and smooth and uniform.

 

I guess it was some guy in Japan at the factory.

[datzenmike]

By Pass

 

The by pass is a pipe connection from the thermostat housing down the front of the engine to the lower radiator hose fitting on the timing cover. If not used, the thermostat must warm up slowly from heat convection through the coolant and the aluminum head. This can lag well behind the actual internal engine temperature. The by pass allows some small coolant flow past the thermostat and then feeds it back into the engine. The thermostat samples this forced flow of hot water and responds more accurately. The coolant that circulated through the intake runners is simply connected out to the already there by pass.

 

Earlier L16 probably didn't have the by pass and relied on a 'jiggle valve' on the thermostat. This was a tiny hole that did basically the same thing as the by pass. It allowed a small flow out past and through the thermostat. The problem was the warmed coolant went into the radiator pushing cold water into the engine. Not something that speeds the warm up. The by pass sends it directly back into the engine.

[Gp620Rat]

Thanks, great explanation.

[Gp620Rat]

April 23? Same here! Coming up…

[Gp620Rat]

Stick with the stock valves? 35/42?

[datzenmike]

9 minutes ago, Gp620Rat said:

April 23? Same here! Coming up…

 

Birthday, yup.

 

 

2 minutes ago, Gp620Rat said:

Stick with the stock valves? 35/42?

 

The L heads flow pretty well so a larger valve isn't going to change much till it gets really revved up. You would want to port the intakes if going to larger valves, at least. It can only flow what the port can pass

[Gp620Rat]

I’ll stick with the stock valves

[Gp620Rat]

Do you have any cam recommendations? sources?

[Gp620Rat]

It looks like Z car Depot has a competition/street cam for the L20B for $309.

[datzenmike]

Wish I knew the cam specs for the L20B. All cam grinders today speck their cams at a specified 0.050" lift so apples to apples. I suspect Nissan's 248⁰ is right where the lobe ramps up or down on the base circle. I could very well be wrong about this. 

[Gp620Rat]

I believe that those “how to“ books from Tom and Frank spell out exactly what the L20B cams are doing … i’ll have to check; but if memory serves, I think you are spot on.

[datzenmike]

I've seen some after market cams that had the 248⁰ duration speck and I asked myself how is this any better than the stock cam? If the stock cam is 230⁰ (or w/e) then this makes more sense.