DCOEs for L20B and few other questions

Engine, Transmission and related drivetrain.
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JonnyCanuck
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DCOEs for L20B and few other questions

Post by JonnyCanuck »

Hello,

Still fairly new to the Realm, so pardon me if this has all been discussed ad infinitum already, but I've done a little reading and didn't come up with too much.

I'm probably at least half a year away from being able to actually *get* my car, so decided to start collecting a few choice items in advance of it's arrival. Not always the best strategy, but it will have been 12++ months between paying for the damn thing and maybe getting to drive it around, so it's kind of preventing me from just throwing my hands up in the air and buying another project while I wait. (Which means, absolutely nothing will get done on the 510 when it gets here, and I don't want that.)

As mentioned elsewhere, it's a 70 wagon, already swapped up to a L20B, 5 speed of some flavour, 32/26 Weber, Rabbit radiator, lightened flywheel etc... couple other goodies. No doubt it will need a bunch of the usual maintenance work and cleaning up, but this seems like a good place to start for a complete noob with 510s. I aim for the this to a fun/lively car to drive, so probably a lot more money going in to brakes and suspension than engine. I prefer using my gears on relatively slower twisty roads than outright speed on a highway/race track etc... (It's modern and comparatively heavy, but if I need to get my speeds kicks, the safety/speed combination of my turbo Subaru wagon is all I need. The little Datto hasn't much chance of matching it, so why spend a fortune trying to make it so?) Also, I would prefer it was trustworthy and driveable as I would love to take it road tripping, or out camping etc...

I would really prefer to keep the L series for the time being, and get to know the car, before even *considering* a swap of any kind. Realistically, it will probably be lack of/cost of parts to keep it going that would precipitate a swap in time, but I don't want to worry about that yet.

Lots of preamble, but I wanted to set up for a couple questions.

- Thinking of upgrading to twin Weber 40s. I don't have the impression the 32/36 is up to the task of fuelling a 2L with maybe a little extra cam in it, but I am willing to be proven wrong. Also, who doesn't like whooshy induction sounds from a bank of carbs.
Anyone out there have any experience with any of the Chinese DCOE replicas? This isn't an unlimited funds build, and I've *generally* been more impressed as time goes on with the quality of Chinese made stuff. I wouldn't want to be the first person here to get them, principally because I have nothing to compare them to, and wouldn't know if they were any good. I've only ever dealt with Keihin/Mikuni carbs in the context of my motorcyles, so this is all new to me. Still at less than half the price of the Spanish units, and *apparently* they accept standard Weber jets etc... it seems like not a bad place to save some money? That being said, it seems legit Webers hold resale value for.... decades? while I've not found any used Chinese copies for sale yet.

- I would want to pair those up with a wideband for tuning. I'm not a tech, but I do know how much time you can spend (waste) doing plug chops and reading plugs. I would prefer to just *know* where my AFR is. Recommendation on a good price/quality brand would be appreciated.

- I do own a copy of the 'how to modify L series engines' and have been through it a little, but is there some simple real-life advice on what I should prioritize in term of giving this thing thorough check out when it arrives? First things to fail, simple stuff to check and assess the usefulness of the motor. (special tools I may need to buy/make to get any of this done?)

-Head selection seems to be a big one for making the most of these L series engines. Assuming this is an unmodified L20B out of a period truck, which head should it have come with? I gather the 'peanut' heads are well like for mild performance use, and can start keeping my eyes open for one... thoughts on what they should be worth these days? There have been many on Ebay, but I have little faith in prices there being anywhere near realistic. It's been a few years since I've bought much of anything there.... Again, am I barking up the wrong tree? Will a stock head probably fulfil my needs?

- reading seems to indicate that the stock exhaust manifold will be just fine for the intended purpose, maybe just larger diameter piping under the car. (easy enough)

I realize much of this might be much clearer when I have the thing in my possession, but gathering ideas and opinions now is going to make it all a little easier when it does arrive and allow me to maybe get things in motion a little quicker then.

Much thanks in advance.
‘71 510 Wagon
‘05 Subaru Legacy GT wagon
Ontario, Canada
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bertvorgon
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Re: DCOEs for L20B and few other questions

Post by bertvorgon »

I can only offer that through the race shop here, Specialty Engineering, that the quality of the Chinese knock-offs has been hit or miss, simple as that.

Stay away from the Innovate wide band!

I bought, in the spring, and AEM one, simple to hook up and used exclusively on the race/street cars out of Specialty Engineering. It uses the latest O2 sensor technology and response is FAST, Model # 30-0300, comes with Bosch LSU4.9 sensor. You can also order the optional gauge face plate..WHITE. I have not installed my white face plate yet.

You can just see the nice bright display on one of our summer drives.

https://www.amazon.ca/AEM-30-0300-Wideb ... B0184TSI84

Hope that helps.
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Re: DCOEs for L20B and few other questions

Post by datzenmike »

L20B heads

The earliest L20B that I know of is the '74 610. Only the 710 and the 620 had an L series engine that year and they were L18s. The '74 L20B has I believe an A87 head which was used on the previous year '73 L18 and the '74 710 and 620 L18s. I had a '74 710 and it was an A87

For '75 through '77 the 620, 610, 710 and S10 200sx all used the U67 head with the co-joined intake and exhaust manifolds without the coolant ports through the intake runners.

For '78 through '80 the 620, the S10 200sx, the A10 HL510 and the 720 all used the W58 head which reverted back to coolant in the intake runners, had round and not square exhaust ports that had round steel liners in them. Otherwise same valves as the U67

The L20B cam is unique to it although only the '74 620 L18 did use it.


These was never a close chamber head used on any L series engines that I know of. Over 50 years, many low mileage JDM engines have been imported with a variety of different heads on them and the heads or entire engine swapped because it was cheaper than a valve job or rebuild. Think about it, Nissan would never put high compression high pollution closed chamber heads on export cars to the North American market and risk being caught at it.

If running a square exhaust head an earlier L16 4 into 2 cast iron manifold is desirable over the L20B that dumps all cylinders into a single pipe manifold. When hunting for an L16 manifold, beware!

Image

The one on the left is what you want. Each firing cylinder is separated from the next firing cylinder by a cylinder on it's exhaust stroke. The left one has 1 and 4 on it's own pipe and 2 and 3 on it's own pipe. The manifold on the right has mangled all cylinders together to find their own way out the two pipes provided.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs
JonnyCanuck
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Re: DCOEs for L20B and few other questions

Post by JonnyCanuck »

Excellent advice on both counts. Thanks very much.

I had been looking at Innovate widebands to mount one on my bike for tuning a new set of carbs. Glad to hear that the AEM is solid unit, and around the same price. I'll get one of those and a couple of bungs and caps so I can move it around my vehicles as needed.

As far as heads/headers go, I suppose I will have to wait until the car is here to get a better idea of what I've got, and see if I even really need to replace anything. Very illustrative photo, I certainly would not have known the difference between the two without seeing it first, or being able to put my hands on some and seeing the flow path in person. (Not often the case when buying almost everything off the Internet.)

There is a guy down the road from me with an intake manifold for 2x DCOEs. For the price he is asking, I will probably grab that, and pretty it up. (He also has a set of Weber 40s, but is asking a premium as they are period correct and matched for an Alfa Romeo....)

On that note, however, he also has a Datsun manifold for a single DCOE. Any thoughts on going that route instead? Since this won't be a *race car*, just something that will get some spirited driving on occasion, would a single, larger carb be sufficient? I realize there would probably be a somewhat less efficient/equal mix to all cylinders vs. a twin set up, but as an upgrade from the 32/36 that is already on the car, is seems like it might be a good middle ground from a performance vs. price perspective. I imagine it would be a little less headache than trying to keep 2x carbs in perfect synch etc...

Cheers!
‘71 510 Wagon
‘05 Subaru Legacy GT wagon
Ontario, Canada
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Byron510
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Re: DCOEs for L20B and few other questions

Post by Byron510 »

When talking performance on a cruiser, and assuming your not recognize the thing to the moon, any side draft really won’t do much more than your 32/36. Intact you’ll have better low end torque below 2500 RPM with the 32/36 with an otherwise identical engine.
On the flip side, throttle response with a twin side draft set up, and the pure sound of intake joy - well if that’s you game, you just can’t beat the side drafts! And I totally get that, trust me I love that sound too.
But you mentions a single dcoe....just walk away my friend!
Here are my thoughts. Any side draft has its disadvantages, they hate being cold, and done have a fast idle circuit combined with a choke, so quite honestly they are a pain in ass to start on a simple cruiser. The 32/36 clearly has an advantage here. You love side drafts for the reasons I mention above. Inter a single side draft, you don’t get the benefits of the twins from a performance point of view, and you do get all the drawbacks. It’s just not worth it! Honestly go twin side drafts or don’t bother spending your money at all is my opinion. I’ve been trying to sell a single 45 on a cannon manifold for 10 years, but I’m hard pressed to look someone in the eye and tell them that this is a great set up!

Byron
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JonnyCanuck
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Re: DCOEs for L20B and few other questions

Post by JonnyCanuck »

Again, great advice.
I tinker with all my stuff, and know a little about carbs on bikes, but as stated elsewhere this is my first experience with a carb'd car, and everything is a learning experience.

2 x DCOEs it is then.... I didn't know they don't have a fast idle circuit, so that's interesting, but nothing I can't work around. And yeah, whooshy induction noises? Lurv it. (Even tho they cause me endless headache, I still have individually filtered carbs on my daily motorcycle, for exactly the same reasons... just a little more throttle response and it's sounds awesome when you get on it.) I just ordered in a copy of Des Hammill's "How to Power Tune Webers...." so I can get a leg up on understanding their innards before getting too far into the project.

I recognize this will end up being a *fairly* expensive upgrade, and I might not gain too much, but I *do* like throttle response to be snappy, and with some of the windy country roads around here, I will not be revving the thing out all the way, but I would expect I'd be staying North of 2500 rpm for most of it? I will probably hang on to the 32/36 and associated hardware in the event I don't love the swap.

This is planned to be a bit of a weekend warrior/garage queen. (That may well change if I fall in love with driving it.) Niagara region uses soooo much salt, I normally wait about a month after the snow is gone and the roads are clear to go out on my bike, or summer car. Makes a short season for motoring about! Also: I *did* just buy a 50 year old station wagon... I've clearly demonstrated that I am willing to part with largish amounts of money for trivial things I want. Hah!
‘71 510 Wagon
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Re: DCOEs for L20B and few other questions

Post by JonnyCanuck »

Actually, might as well attach some photos (actually links, I guess) to make sure I'm not getting entirely the wrong stuff.
The intakes look longer than some others I've seen available for L engines. DCOEs look like pretty big carbs, so I don't want to get stuff that will cause fitment problems.

https://i.ebayimg.com/00/s/NjAwWDgwMA== ... 0/$_59.PNG

Seller is asking $200, which seems fair based on my limited knowledge. (I need to research how to post photos here)

https://i.ebayimg.com/00/s/NjAwWDgwMA== ... W/$_59.PNG

Also, $1000 for the carbs themselves, which he says is *somewhat* negotiable....

Initially, I though that was pretty high for used, but correct me if I am wrong. (Missing linkages and trumpets, this seems a little steep.) On the other hand it seems to be around $1000 USD for a set of new ones.
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bertvorgon
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Re: DCOEs for L20B and few other questions

Post by bertvorgon »

Maybe this link will help too.

I'm good on 32/36, but no experience on single/duel Webers. here is a link to a good Weber Tuning Manual.

https://www.lainefamily.com/images/Webe ... Manual.pdf
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

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1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
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Re: DCOEs for L20B and few other questions

Post by datzenmike »

Image


Motorcycle? Can you find a set of R-1 carbs??? Have an intake made or make your own like I did. These are basically like the SU carb. Constant velocity so it only opens as needed. You can floor it at 1,500 in 4th and it doesn't fall on it's face it just pulls. No need for an accelerator pump because of this. Also has a cold start enrichment that I set up as a pull choke (also has a fast idle) and there's an idle speed adjustment that I cobbled together with an old speedometer cable so I can set a fast(er) idle from in the car.

Image

Made some 1.5" exhaust pipe into trumpets. This seemed to pull the hardest but had to shorten them for the 280zx air filter clearance. Had to convert to throttle cable from linkage. I have the Innovative AFM and it works just fine. Idle jets turned to 3.5 out seems to get the best 14.7 idle. Bought a bag of motorcycle jets from Amazon and drilled them out. Ended up just slightly smaller that the stock 146 for a 14.7 cruise and mid 12s floored. Very happy with the results... WAY better than the stock Hitachi. However I mostly learned what NOT to do while designing and building the intake. I would guess R&D probably ran $400 in dead end experiments for what ended up being less that 2 feet of 1.5" exhaust pipe and an 8" x 4" x 1/2" piece of scrap steel. Even with the air filter on it drowns out the exhaust starting at 2,500. It's quiet enough just driving but everyone knows it when you get on it.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs
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Re: DCOEs for L20B and few other questions

Post by JonnyCanuck »

Well,

There certainly are lots of options to choose from. I've seen the motorcycle ITB/carb setup done a couple of places, and it sure does look pretty wild. I believe you when you say it must respond well Datzunmike. I don't know exactly what redline is on an R1, but think those carbs should measure up when you figure that it probably turns 14k or more? And that is an engine that is much more efficient at pumping air than an L series..... I think my biggest concern with putting something like this together is cost. I can't see it retaining much re-sale value, while the Webers, tho expensive seem to sell for almost as much used (in good condition) as they cost new. I suppose it comes down to how likely it is the L is going to stay in the car long term.

If I decide I like it, and it is enough engine for me in a 2000lb car, then I will do whatever the hell I want, within my budget. If, with the 32/36 well adjusted and the engine running as well as I can tune it, it still doesn't scratch the itch, then out comes the L and in goes whatever makes sense, and had some community around a swap. I'm not going to make any hasty decisions until I've had some time with the car.

I suspect there will be many, many things I have to deal with along the way before making choices like that. The car is still in Florida, and will be for the foreseeable future. This is collecting data, opinions and some gear I will need along that way to have in anticipation of it's arrival. Or, even better, maybe going down to drive it back myself. I'm new to the forum, and don't want to do the thing where I just bought a 510 and now it's gunna git a SR20TT, derp derp.

I've never actually seen a 510 in person. Only via photographs and video etc... So, I literally have no frame of reference of what to expect. Just always thought they were great looking little cars from the era of automobiles I have always been most interested in. My Dad had a 240z, and I remember that pretty well, and guess I became a Datsun tragic because of it. All I wanted for years was a 240, but tragically they are entirely out of my price range these days, and they didn't come in a wagon version!!

So, continued thanks for the info. I'll keep on reading here, (and ratsun.com, etc...) to try to make sure I'm not asking useless questions that have been answered a hundred times before.

Cheers!
‘71 510 Wagon
‘05 Subaru Legacy GT wagon
Ontario, Canada
Rat-a-tat-Datt
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Re: DCOEs for L20B and few other questions

Post by Rat-a-tat-Datt »

Hi JC, I feel your pain when it comes to making the right decision with carbs.
My story was defined by performance and horsepower.
The original Hitachi lacked both.
Perused the internet and determined, with the help of other forums, a dual carb set up on the L20B was very doable but presented a necessary but small learning curve - to be able to tune them properly.
However, once I pulled the trigger and sourced out a set of used DCOE Webers ( the ones you're viewing right now, are definitely at the high end range ), I bought these remaining components and assembled everything, ie: intake mani, exhaust mani and throttle shaft.
My current set up is dual Weber 40 DCOE 151's with a Cannon intake, Red-line throttle linkage and a tri-Y exhaust mani ( the left one in the previously dated pic ).
My W58 peanut head was modified, opened and matched ports with the exhaust liners removed, then added a mild cam and a 2" single runner exhaust system.
My only issue, at this time, was tuning the carbs to where they'll preform to my liking. So far I've just replaced the emulsion tubes ( used is what you get - someone else's tuned carbs ), which has helped considerably.
Conclusion, well worth the experience and money!
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Re: DCOEs for L20B and few other questions

Post by bigjim5551212 »

The Chinese DCOE from FAJS are pretty fine carburetors. I have to look at this page more to comment more
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Re: DCOEs for L20B and few other questions

Post by Downeaster »

Hi John have run 45dcoe for many years. have only delt with the real Italian ones so can't say good or bad about the new china product. As far as tune set up there will be many factors. compression ratio/cam/pipes/intake/displacement/ignition/air filters or horns. SO with that note this is what I ended up with this summer with our new fuel BS.

MOTOR: L-16 BLOCK
L-18 CRANK/RODS
84MM FLAT TOPS
A87 HEAD CLOSED CHAMBER
RACER BROWN 56 CAM-270/520LIFT
LIGHTENED FLYWHEEL/CLUTCH
DATSUN COMP INTAKE
STHAL STREET HEADERS
SSS DIST 10DEG-36DEG@3400RPM




brass float with 200 needle
36 chokes
#1 venturi
45 F8 idle jet
F11 tubes
100 air jet
145 main jet
check valve in float bowl for accelerator pump
45 mm pump rod spring
60mm pump rod
50 pump jet

NO CHOKES (NOT CONNECTED)
enjoy the ride hope it all works out
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