Another EFI IDA 'Weber' thread...!

Since I like a project over winter, which inevitably takes me into summer and I don't get to use the car. Here we are....

This idea stemmed from loving the look of '8 stack' Webers, but hating the idea of going to back to carbs, let alone 8 of the buggers.

So after a bit of googling and not liking the look of the Borlas, the cost of the Iglese, or the injector position of the Jenvey's, it kinda lead to doing it DIY.

I wanted the classic looks, for it to cost sub £5k (including the ECU) and have a sensible injector position.

I came across this thread on the GT40 Forum - GT40 Forum

Jasper had the same idea I did, but only got it so far before shelving the project.

Still it was a base to start from.

I ordered the same Blue Thunder inlet he had from the states


Along with some Chinese replica Webers


When these arrived I was super surprised at the quality, the castings are far better than the Spanish Weber castings! I'd never want to run fuel through them, but they certainly look the part.

I couldn't resist a quick mock up in the engine bay






Looks great but its a long road ahead.

The next step was getting the throttle linkage all built up as a test. I ordered the linkage bellcrank from Australia and the linkage arms from Webcon in the UK.


Might raise it a little depending on where I can get the injectors to fit.

Also I had a go at mocking the throttle position sensor up. I want it around the back out of the way.


So I removed this bolt from the main shaft and used this little Ali D piece, I got the blank for it from Emerald.


Quick test fit of the sensor and it fits quite nicely with room to make a bracket for it.


The next step was to try and be an engineer


Some dry shampoo on the bit I want to scan, so it’ll pick it up.


Ta da


I've still not used this scan for designing the bracket for the sensor. I will though soon.

After a lot of soul searching I decided I didn’t want to muller into my £1500 inlet manifold to try and fit some injectors at a daft angle, like Jasper did. I just couldn't help thinking I'd run into clearance issues everywhere.

So after a lot of messing, (Hours and hours of designing and measuring) I’ve made these spacers with injector bosses in them.




Will test fit with these then print them in nylon.
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Fit seems good. I’ll have room to get two fuel rails between them.



My first time printing with carbon fibre impregnated Nylon.

After a few modifications to the Ender. All metal hot end and some hardened nozzles.

Wish me luck.


Some time later....

The print took 9 hours but it came out lovely and is very strong.

I can stand on it, and I'd definitely fit in the category of 'powerfully built executive'.



Tight packaging is tight.

I’ve moved the leading injector inboard by 3mm on the latest prints to give me a bit more room for the fuel rails.


Good job the bonnet has a vent…


Please to announce the throttle linkage fits... just



Fuel Rails fitted (Its quite tight)



I'm going to take 5mm off my bell crank stand to give a little more room.

To constrain the rails, I made up these little brackets.


Printed in carbon Nylon like so:



Poor photo of one fitted

Big update time!

I’ve been told to get this finished soon by Mrs W.

As the office, “is a f**king state”.


Completed the map line take off and the brake vac take off.


Also finished the TPS mount



More thinking.


Hole in the middle at the bottom is for the idle control air.

Tried loads of different ideas to plumb it to an idle valve. All of them required too much hose and fittings.

MG rover to the rescue. K series idle valve bolts straight up with a little 3d printed spacer.


Fuel system this weekend:

Made a little holder for the fuel filter so it can live at the back rather than the engine bay.


Fuel reg, sensor and fittings plumbed in.


ITB’s fitted and the engine side of the loom is done. Also done some random plumbing etc etc.

I hate wiring!!!!!!!



Also got the throttle linkage done. I had to go out and buy a new slightly thinner cable though to work with the bell crank.

When first set up I couldn't get full throttle, I’ve lengthened the pedal throw now, so should be grand, and a bit like a TVR to drive, as they have really long throttle pedals.


Rails in, injectors wired up, we have pressure too!



Ecu is in the car too.


Also made a little bracket for the manifold air temp. Need to make it a little more rigid.

The ECU is alive!


Now set the crank and cam sensors in the fancy distributor


Well these HT’s are as tight as they could be!


Since there’s sensor inputs may as well used them.

Fuel pressure


Oil Pressure


Nothing is fun on a Sunday like taking an angle grinder to your bonnet.


Todays job - Mapping.

Never done an Alpha N tune before.


Far left screen - Terminators self generated VE map.

Centre screen - Old map from the Holley Sniper

Far right screen - New map using Alpha N

What’s impressive was how close the Terminatirs self generated maps was to my old one.

Now the fun of working out where all my fuel flows should go on an Alpha N map.

Things like idle and cruise will all be in the bottom rows, then it’s a case of filling in the WOT fuel and joining the dots.


The last photo is the old Sniper map flipped back to VE so you can see where idle and cruise was affecting the map.

So the little idle block needs transposing to the 1-2% TPS line on the Alpha N map and the lean cruise area needs to side in the 3-9% throttle area of the new map.

Since this all hurt my brain after a while, I had a break and did an alignment with my DIY string kit


All in spec, which is impressive since I eyeballed the re fitting of the rear end.

Oh you are beautiful. So happy with it.





Its all up and running now, tuning though came to an abrupt end, when I'd forgotten to put any fuel in it....

What did you do about the chokes in the IDAs? I recall that these chinese carbs are set for VW applications, so the chokes are on the small side (38mm?)
I've removed them and fitted a sleeve in place of them, to allow for the retention of the top venturi for the classic look.
Very nice write up Stephen. Please let us know how the tuning and run ability. Looks very nice.

Regards Brian
Tuning and drivability is great so far.

I only have one issue though, the carb don't want to return fully to idle when the throttle is let back slowly, they stop at 4% open, which gives a rather interesting 3krpm idle!

They will 'snap' shut if I prod the throttle pedal. I'll have a look to see if my linkage is galling anywhere, as well as maybe a return spring on the bellcrank.
What did you do about the chokes in the IDAs? I recall that these chinese carbs are set for VW applications, so the chokes are on the small side (38mm?)
The sleeves I made for the replacement of the chokes.


Yes I still have a 0.8mm lip near the throttle blades, I'll deal with this in the future.