280z EFI - Triple Weber Conversion (My Process)

BenjEtch

Club Member
Hi all,

Thought I’d put together a bit of a thread to help anyone doing a Datsun 280z EFI to Weber conversion, or even swapping carbs for Webers on the earlier Z’s. There is heaps of information on the process, but it's here, there, and everywhere, so this will hopefully bring it all together for anyone currently doing the swap, or even thinking about it!

I’ll break the thread down into a few posts as it takes a short while to put everything together, you might have to go digging to find future sections!

Please note, I'm no professional, so some things I've done and products I have bought might seem odd/backwards so please feel free to suggest better alternative products!

So firstly parts, I’ll list mine and where I got them from, however, there are alternatives - I’ll try and list these too.

Alternatives Websites - before buying any parts check these websites and eBay as you might find parts cheaper:

Fast Road Cars Website : https://fastroadcars.co.uk/store/
Classic Carbs : https://classiccarbs.co.uk/
Webcon : https://www.webcon.co.uk/products/c22-weber-carburettors/
Eurocarbs : https://www.dellorto.co.uk/

My Shopping list:

1. 3 x Weber DCOE 40’s x 3
/ eBay / £1079 / https://www.ebay.co.uk/itm/154665791912

2. 1 x Intake Manifold / eBay Japan / £500 / https://www.ebay.co.uk/itm/284878880824

3. 2 x T Fuel Unions / Classic Carbs / £25 ex VAT & delivery / https://classiccarbs.co.uk/product/...ttor-parts-twin-404548s-1x-t-piece-fuel-union

4. 3 x Weber Choke Blanking Plate / Classic Carbs / £13 ex VAT & delivery / https://classiccarbs.co.uk/product/weber-carburettor-idf-dcoe-choke-blanking-plate-csp

5. 1 x Weber Injection To Carbs Step Down Fuel Regulator / Classic Carbs / £60 ex VAT & delivery / https://classiccarbs.co.uk/product/...n-carbs-stepdown-fuel-pump-pressure-regulator

6. 1 x K&N Air Filter 62-1420 / eBay / £27 / https://www.ebay.co.uk/itm/381928890693

7. 1 x K&N Air Filter 62-1340 / eBay / £24/ https://www.ebay.co.uk/itm/284605834231

8. 3 x Weber DCOE Throttle Lever Ball Left Hand / eBay / £65!!! / https://www.ebay.co.uk/itm/361182232826

Shopping List Breakdown:

1. 3 x Webers DCOE 40’s or 45’s

I went for “Weber DCOE 40’s 151” as from what I’ve read the 45’s are overkill for street use.

2. Intake Manifold
I went for a Harada Intake Manifold (because of availabilty) which is apparently suitable for both Webers 40-45 and Mikuni 40-44 according to the eBay listing.

There are also Webcon and Mangoletsi inlet manifolds which you can get from Classic Carbs & Eurocarbs - the other websites might stock these too. The Mangoletsi version was well priced but out of stock - July 2022.

3. 2 x T Fuel Unions
My Webers came as standard with only an inlet fuel union. These T unions allow you to run one fuel line across all 3 Webers. See pictures for reference.

4. 3 x Choke Blanking Plate
These are to blank off the choke cable assembly if you don’t want to use a choke. Apparently Webers don’t really need them. The blanking plates are more for looks as I don’t believe leaving the choke assembly on and not using it causes any problem. (Probably not needed - I haven’t installed mine yet).

5. 1 x Weber Injection To Carbs Step Down Fuel Regulator

I got one of these instead of running a low pressure pump, because I had literally just bought a new high pressure EFI fuel pump before starting the conversion. This takes the fuel from your high pressure EFI pump and reduces it to between 1-5 psi (can be controlled I think). This regulator does need a return line though so don’t remove it from your car when you take all the EFI out.

For anyone interested I bought the Sytec OTP020 - Inline Fuel Pump from eBay for £84.99 as it looked to have a very similar footprint and all the connectors needed. Might not be the best option, but works for me and seems to be very quiet. https://www.ebay.co.uk/itm/160822629333

I also run an inline filter between the tank and the pump and also one in the engine bay. Both parts are here - Inline filter https://www.ebay.co.uk/itm/272098769145 / Sytec engine bay fuel filter ebay.co.uk/itm/224584354116 (probably overkill)

6. 1 x K&N Air Filter 62-1420
This filter is for the crankcase vent as there is a hose removed when you remove the EFI equipment

7. 1 x K&N Air Filter 62-1340
This filter is for the valve cover breather as again there is a hose removed when you remove the EFI equipment.

8. 3 x Weber DCOE Throttle Lever Ball Left Hand
This was a frustrating one and I was amazed at the price for 3 pieces of metal. The Webers as standard came with a certain type of throttle lever, this isn’t compatible with the throttle linkages on the Harada intake so I had to get 3 of these with the ball joint on. There may be another way round this by swapping out the linkages or finding an alternative part that is compatible with Webers.

Important Links:

Below are the many links I used during this process, some are videos and some are threads.

Datsun 280z Removing the injection system to fit carbs | Carburettor conversion:
280Z Old ECU Harness Removal !!UPDATED VERSION!!:
Removing L28 Fuel Rail | Datsun 280zx Build:
Datsun 280Z Ep.14 Removing Intake Manifold:

Here’s a link to an in-depth wiring diagram (in colour and super high resolution): https://zclub.net/community/index.php?attachments/n77zcar-wiring-pdf.40926/

Links to other threads that helped massively:

280z EFI to weber electrical issues: https://zclub.net/community/index.php?threads/280z-efi-to-weber-electrical-issues.27507/
280z EFi to Triple Webers: https://zclub.net/community/index.php?threads/280z-efi-to-triple-webers.27495/
Converting from EFI to Triple Weber setup: https://forums.hybridz.org/topic/128404-converting-from-efi-to-triple-weber-setup/
Converting to Weber Carbs, what do you think?: https://www.zcar.com/threads/converting-to-weber-carbs-what-do-you-think.270569/
Weber jets??All who live for their triples please read this: https://forums.hybridz.org/topic/28...for-their-triples-please-read-this/?hl=webers
 

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SeanDezart

Well-Known Forum User
The Mangoletsi version was well priced but out of stock - July 2022.

6. 1 x K&N Air Filter 62-1420
This filter is for the crankcase vent as there is a hose removed when you remove the EFI equipment

7. 1 x K&N Air Filter 62-1340
This filter is for the valve cover breather as again there is a hose removed when you remove the EFI equipment.


For info, I have all the Mangoletsi inlet manifolds in stock however the Harada is a good piece of kit.

I wouldn't reccommend fitting those cute looking breather filters unless you want to see your engine bay covered in greasy deposit after a while - fit a cheap, Ebay shiny catch tank and connect both to it !

Great info btw - keep at it :cool:
 

status

Well-Known Forum User
I’ve had one of those breather filters in my Z for over twenty years and never had a problem with a dirty engine,a catch tank is probably a good idea if your engine throws out a lot of gunk
 

SeanDezart

Well-Known Forum User
I’ve had one of those breather filters in my Z for over twenty years and never had a problem with a dirty engine,a catch tank is probably a good idea if your engine throws out a lot of gunk
You can't see for shit anyway.....and when does a rock god open up a simple bonnet ?
 

corn0717

New Forum User
New to the forum but have been scoring the web for answers to questions on weber conversion for my 77 280z. Thank you, BenjEtch, for the great information complied here.

My question right now is can i switch to a 240 or 260z thermostat housing and clean up the look by getting rid of a couple of the sensors that belonged to the FI system?
 

BenjEtch

Club Member
New to the forum but have been scoring the web for answers to questions on weber conversion for my 77 280z. Thank you, BenjEtch, for the great information complied here.

My question right now is can i switch to a 240 or 260z thermostat housing and clean up the look by getting rid of a couple of the sensors that belonged to the FI system?
Not sure on that one actually, haven't got that far with mine.
 

corn0717

New Forum User
Thank you for the response. I don't think its a very critical issue. I may just leave it for now and change it later to an earlier housing if i find a good cheap one.

Half the fun of the conversion is figuring everything out.....what heat shield, choke setup, and other odds and ends are needed. It's a fun project to do with my son.
 

BenjEtch

Club Member
Thank you for the response. I don't think its a very critical issue. I may just leave it for now and change it later to an earlier housing if i find a good cheap one.

Half the fun of the conversion is figuring everything out.....what heat shield, choke setup, and other odds and ends are needed. It's a fun project to do with my son.
It is indeed, there are tonnes of helpful info out there, but it's never really been combined into one post. A lot of people say you don't need a choke on the Webers, are you going to run a choke?
 

corn0717

New Forum User
Yeah, i think I'm going to. We live in the mountains in Colorado at 8000 ft above sea level. It may be very rare to need a choke but it may come in handy on occasion.
 
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