Conversion from triple Solex's to Jenvey throttle bodies.

Conversion to throttle bodies.

In this post I have endeavoured to describe the components and other changes required to convert from Solex carburettors to Jenvey Heritage throttle bodies.

Some of this content may have been included in previous posts, however I think it is worth having one specific post specifically for this part of the project.

My feedback to anyone thinking about this is, it's a lot of work! Made doubly difficult if the engine is fitted. For me as the whole car was stripped down it was the ideal time to do it.

Fuel line update

The fuel system changes that are necessary:

• Additional filter, pre low pressure pump
• Fispa regulator is replaced with a swirl pot that has an integral high pressure pump and regulator and filter.
• A return pipe from the swirl pot back to the tank

(note the High Pressure Filter is integral to the Jenvey swirl pot)

Picture shows Swirl pot fitted in place of the Fispa regulator as well as the return fuel line.

The Jenvey EFI swirl pot with integrated high pressure fuel pump and pressure regulator has been designed to convert low pressure fuel from the low-pressure fuel pump to high-pressure fuel for electronic fuel injection. 

It includes an integral 3 bar fuel pressure regulator on the return side. It has been designed to swirl fuel from the low pressure pump and high pressure return ensuring liquid is centrifuged out forcing air into the middle / top of the pot which then escapes via the bleed.   This ensures there is a constant feed of high-pressure fuel to the engine even when the fuel tank level is very low and the low-pressure pump start drawing air. 

Internal baffling and a 60 micron filter built into the internal pump pickup

https://www.jenvey.co.uk/swirl-pot-setup-sytec

Inlet Manifold

The inlet manifold was modified by inserting a baffle between the siamesed ports.

An additional water temperature sensor was added as required by the ECU, allowing the original analogue temp sensor and gauge to continue working as normal.

Engine

During the engine rebuild (Bob Dove Motorsports) a crank trigger wheel was designed, manufactured and fitted. The required sensor was attached to the engine.

List of Sensors

The following sensors were fitted to various parts of the car, none of these are visible to the casual viewer.

• Crank position sensor (see previous paragraph and photos)
• Water coolant temperature  (see earlier paragraph and photos)
• Air intake temperature sensor
• Fuel pressure sensor
• Knock sensor
• Throttle position sensor is built into the Jenvey throttle bodies
• Lambda oxygen sensor

ECU

I used the EMU Classic Black ECU

Wiring loom

The wiring loom was created using a set of colour coded and id printed sleeves from the ECU manufacturer. The design, layout and make up of the loom is quite a task, especially if like me if you have never done it before!!

I added a relay to control a new external electric fan, triggered by the ECU

Clean 12v feed to ECU via relay

Clean feed for Swirl pot via relay

Heritage Throttle Bodies

Jenvey Dynamics, Bridgnorth, WV15 5HP, UK

Dynamo

I wasn't planning to replace the Dynamo, but at start up I did get some interference and guessed it was the Dynamo. I have replaced it with a Dynator for Wosp https://www.wosperformance.co.uk/dynators

Dyno

Now you need to find a good tuner who really knows the ECU of choice, my final run-in and tuning was successfully completed by Page Motor Sport

I ended up with a very smooth power curve and flat torque curve. I did have a small vacuum leak on one of the mounts which probably lost be about 5hp. However with 148hp at the wheels I'm happy.

See the video of of one of the power runs

Alfa Romeo 2600 Spider restoration - August 2025 update

Big progress has been made throughout the summer. The car was moved from my garage to a company who allowed me to work on the car on their lift and provided extra hands for the heavy lifting of the engine etc.

Engine & Gearbox

The engine and gearbox is in, biggest hoist ever!! The heritage throttle bodies are fitted and looking the part and the harness for the fuel injection is finished for the injectors, knock sensor and lambda.

The throttle control bar was well worn, so I had a small engineering shop create a new hollow bar and re-bush the casting.

The exhaust has been fitted with the lambda sensor adapter.

Cooling system

The radiator and oil cooler have been fitted.

We did have a problem with the drain tap on the block which leaked and had to be replaced, quite difficult to get at once the engine was in!!  We also had to do some remedial work on the output that is situated on top of the water pump, in short it had rotted through and I hadn't seen it. It required drilling and re-tapping to take a new fitting.

The system is now filled and looking leak free, fingers crossed!!

Prop & Diff

The prop shaft was balanced, painted and then refitted along with the renovated differential.

Brakes & Clutch

With disc brake all round the refurbished discs and callipers have been fitted and the system has been successfully filled and bled. Clutch circuit is also fitted, filled and bled.

Suspension

All the suspension is fitted and the car is back on its wheels. The wheel nuts and studs had been damaged probably by the air guns used in modern garages, so the threads were cleaned using taps and dies, and all is well.

The wheels had been cleaned and powder coated, then created a key in the powder coat finish before spraying a coat of paint (hopefully close the the original colour) and lacquer.

Alfa Romeo 2600 Spider restoration - June 2025 Update

Progress stopped over the winter due to us escaping the cold for a couple of months. I started work again in March, doing a day or two a week and have made some good progress.

Wiring Harness

I routed the new harness around the car, this was made much easier as I had labelled it before I took out the old harness. I connected all the rear lights (newly chromed) and number plate light etc, then fitted and connected everything in the engine bay. 

Engine bay

The fuel, brake and clutch lines are in, with refurbished master cylinders and a NOS slave cylinder. The original reservoirs have been cleaned and painted. Everything else is now fitted in the engine bay ready for the engine fit. 

The brake servo has been rebuilt and a NOS non return valve added to the newly painted vacuum tank.

The regulator and relays have been checked, cleaned and refitted.

I think I have fitted everything in the engine bay that I can prior to the engine.

Engine

The engine is fully rebuilt and includes a trigger wheel and crank sensor ready for the fuel injection. 

The fuel system has been changed replacing the Fispa regulator with a combined swirl pot and high pressure pump together with a return pipe to the fuel tank. I will at some point do a specific blog on the injection system design and installation.

Body work

I have fitted the rear bumper, as I was fed up of moving it around my garage!

The original front lights with new rubbers and chrome have been partially refitted as has the front grill which is much easier to fit without the engine in place! 

Alfa Romeo 2600 Spider restoration - December 2024 update

More body work

On close inspection both door skins were in need of replacement. These new door skins were made and from scratch (thanks David!) 

The car went off to the paint shop in May 2024, so over the summer I finished off any part restoration that remained. The engine rebuild is also coming along, more on that in the net update. 

Manifolds

I have had all the manifolds and air plenum aqua blasted. The intake manifold has been de-Siamesed ready for the new throttle bodies.

After a long wait the car finally came back from the paint shop in December 2024, now at last I can start putting the car back together!!

Alfa Romeo 2600 Spider restoration - March 2024 update

Body work.

The underside of the car has been media blasted and epoxy primed. I then spent many happy hours seam sealing all the panels. 

All the panel edges were painted with a brush to ensure coverage before a coat of Epoxy mastic, once this had hardened I sanded the surface and applied a final coat of Raptor.

Engine Bay

I prepped the engine bay, epoxy undercoated then finished with Eastwood UnderHood Black that gives a very low gloss which is close to the original factory finish. I have used Raptor on the cross beams.

Here are the before and after photos.

Steering Box

In a previous posting I said that after I had had a quick inspection and the wear wasn't too bad, that I would leave the steering box alone.  I wasn't really happy with this but as the RHD rebuild kits are hard to come by, I was prepared to live with. 

Then I came across Ricardo Cavallero in Buenos Aires, they make all the bits I needed. As luck would have it I was planning to visit South America during December & January and Buenos Aires was on the schedule!. So a few emails to the very helpful Ricardo and it was all sorted, during my visit I could meet up and pick up the parts.

 - 1 (one) Gear worm & shaft (shaft installed into the gear worm).

 - 1 (one) Roller-kit  ( 1 roller, 1 pin for riveting, 2 oversize washers & the full complement of needle rollers)

 - 1 (one) Lower bearing set ( 1 cup and 1 cage with tapered rollers )

 - 1 (one) Upper bearing set ( 1 cup and 1 cage with tapered rollers )

 - 3 (three) Oil seals

 - 1 (one) Set of shims ( for axial adjusting of gear worm and bearings )

 - 1 (one) Gasket ( for sector shaft cover )

 - 2 (two) Housing bushings.

It all went to plan and I met with Ricardo and his sister and picked up the bits.

Dynamo & Regulator

I decided to do some minor upgrade work on the regulator which has now been converted to a solid state circuit, and the dynamo has been overhauled with new coils etc.

Fuelling

Having read so much on how to set up the Solex carburettors or the alternatively using the optional Weber's, everything I have read says that both options are not ideal and I felt that I would be "chasing" the set up for ever.
So decision made, I have decided to use heritage throttle bodies that look like Weber's.  I will add all the detail of the conversion in a later posting.

Alfa Romeo 2600 Spider restoration - Refurbing many parts

Engine

The engine is apart and looks really good. I have had it dipped and cleaned and I'm now working out what bearings etc I will need. Good news is crank, pistons, liners and valves are all ok.

Refurbing many parts

While the car has been away at the fabricators, I have spent most of the summer examining all the parts that came off  the car. I have kept and will reuse as many of the original parts as possible and have had many hours of fun cleaning, repairing and repainting.

I have rebuilt the heater box, it needed a new valve which sounds easy but the RHD models use a different valve so I ended up using he insides of a new LHD valve and the original outer casing of my valve. Fitted a new matrix while I was in there.

I have had new bushes for all the suspension and most of the rubber parts on the car had hardened and perished.

My spreadsheet of parts that lists everything that has come off the car or has been bought as a replacement now stands at 350 items, good thing is I photographed everything that came off and used the parts storage system that I have used on other cars. It saves hours of work when refurbing and putting the car back together.

Whilst I have managed to source most of the parts I need, none of them are cheap!!

Fuel Tank

The fuel tank was media blaster and no rust inside or out. Amazing. I have sealed the inside using Rustbuster Fuel Tank seal Slosh . The outside of the tank I have painted with a black epoxy.

Dashboard and seats

Are back from being re-stitched, the dashboard ended up being recovered due to multiple burn marks from the cigarette lighter.

Softop Hood

The car still has the original hood from 1964, its a work of art! Having looked at what is available on the market I decided to refurbish and reuse the original hood. It had suffered the same fate as the seats in that the stitching had deteriorated and the foam turned to powder. My fried at Stitchperfect has brought it back to life.

Steering Box Rebuild

I have had the steering box looked at and whilst the is wear its ok it will need a rebuild at some point. So for now, after a good clean its going back on. I'm hunting down the parts that I will need at some time in the future. (See next blog update on the parts)

Chrome

All the brightwork work (nearly all) has either been re-chromed or polished. A lovely job by ACF Howell. 

Non Original Concessions

Whilst I am intent on keeping as much originality in the car as possible, I have decided to make a couple of concessions. 

1. Power Steering

One concession  is the fitting power steering which I think will transform the drivability of the car. The unit fits under the dash and all the steering components in the engine bay remain unchanged.

2. Fuel Pump and Regulator

I couldn't get a rebuild kit for the Fispa regulator, and as fuel is rather important I have decide to fit a new fuel pump and Regulator both of which should perform much better than the 1964 originals.

Alfa Romeo 2600 Spider - Stripping down 2

Interior out

All the interior has been taken out of the car and assessed, the seats were all good except for the foam which had disintegrated to powder and some of the old stitching which had simply rotted.  The seats have gone to Stitch Perfect for repair, the plan is to use everything original.

Clean off floor pan and underside

All the inside of the car has been scraped off, and good news is there is no rust! 

Many hours spent cleaning off the underside of the car, removing the old original bitumen based underseal with a heat gun and scraper, by far the worst job to date! Great news again very solid!

Wiring Loom

I managed to source a new wiring loom from Autosparks. I was a bit sceptical about its accuracy, however after comparing every circuit it was accurate both for colour and completeness. The only missing wires related to the rear number plate light, an easy patch in.

Car ready for fabrication body repairs

After a complete strip down, it looks like the car will need work on the sills, a patch on the boot and rear valance and little bit on the inner wing. Overall I'm really pleased with how solid the car is.

Overview video

Fabrication work

I had the engine bay, underside of the car and lower parts of the doors and wings media blasted to make sure we hadn't missed any rust. We hadn't!!

All the inner and outer sills have been repaired with new fabricated panels

Small repair above the sill

Repair in the boot and rear valance

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