General 1986 1.5 fuel injection?

[razmataz09]

hi there, in my garage i have a 1986 bertone fiat x1/9 1.5 with a single weber carb, and i was wondering, is there a straight conversion kit for a fuel injected system or dual carbs, depending on which has more performance, thanks

 

[jimbro1000]

You can swap the head with one from an early Uno 1300 (turbo or normally aspirated). The head matches the one on your current engine but with some subtle differences to the inlet ports. The plenum chamber is identical to the one originally fitted to the fuel injected X1/9s sold in north america and fits perfectly.

The big problem is the engine management - the early Unos and injected X1/9s used a split injection/ignition system that was actually two separate independent system with separate triggers. If you're converting it is far easier to just fit a single trigger system and use a programmable aftermarket management system.

If you want to go twin carbs then you could go for twin DCOE's but they don't fit without sacrificing the boot area. It is much tidier to fit twin DCN's (most people refer to them as DCNF but that is only true if they were sourced for or from a Ferrari - guess what the F stands for...) or IDFs, you used to be able to get these cheap from Mini Metro GTs (not GTi's) but they are even harder to find than X1/9s these days so your best hope would be to buy them new from a weber specialist (there are still a few in the UK), they should also be able to supply a suitable manifold. If not places like mid-west bayless still sell them. Keep in mind that you are looking at about £400 each for two carburettors plus another £400 for the manifold plus linkage, trumpets, filters, etc. Realistically you won't get much change from £1500 just for the parts. On top of that you'll need a decent rolling road session to get them set up and properly jetted. So plan another £500 for that too.

 

[BirdyX19]

Jimbro you got me excited there for a moment. I need a new carb for my X1/9 and with all that talk I was thinking "ohhhh nice" but I think I'll stick with a standard set up. That's almost as much as l paid for the car.

 

[jimbro1000]

You could just fit a Mk2 Uno manifold as these go straight on if you want to go fuel injection. The later Punto manifold looks the same but has the throttle linkage on the wrong side on the inlet port...

There are other alternatives but it just gets stupidly expensive again

 

[razmataz09]

Well I was hoping for twin carbs for the aesthetics, but those prices :/ what about teconditioned carbs?

 

[ppalma]

Has anyone had any experience using Alfa 33 carburetors? I believe they are 36 IDFs. They are still quite easy to find here in Portugal

 

[jimbro1000]

The IDFs work well and you can get the manifold from mid-west bayless iirc, you just need to sort the linkage out. The 36mm ports are a little small to be honest but for normal road use anything bigger can start to cause problems at low revs/load as you don't the fine control for low flow.

 

[ppalma]

Dellorto and Weber are in any way comparable? I'm looking through ads and I'm finding quite a few Dellorto 36 and 40 IDF. Apparently many of the Alfas that landed here had Dellorto caras.

 

[jimbro1000]

Dellortos are essentially (but not quite) copies of weber carbs, they use the same base pattern but may be significantly different internally. The dellortos are generally more complex in construction and are reputed to work more effectively at the lower rev range while the big Webers tend to be a bit peaky.

You'll find people that swear by one or the other - ultimately the answer is that as long as you keep them properly serviced and balanced you will get good results. The only caveat is that the carb must be the right size for the engine. Bigger is not necessarily better

 

[razmataz09]

This is the current one, is there at least a drop in upgrade?

 

[jimbro1000]

Well the picture shows a European spec Weber 34 DATR - a progressive two barrel carburetor. It is the largest stock version of the DATR model and basically marks the largest single port Weber carburettor you will find that fits stock.

From here - sticking with Weber you would need to move to a 38 or 40 synchronous twin port DGA series but this would require a change of manifold. These can be fitted singly (one port for two cylinders) or in pairs (one port for one cylinder) from there you are onto full on big carbs 36+ IDFs or 40+ DCO series.

If you are using the car on the road you need to tread carefully as a lot of the bigger carbs are race-spec and do not include a choke mechanism making them very, very hard to start even on a warmish day.

Dellorto can supply carburettors still but you are in the same problem as the DGA, IDF and DCO series Webers - they are twin barrel synchronous so you have to change the manifold.

 

[razmataz09]

Right, thanks alot for the help, ill go get clued up and get back to you

 

[razmataz09]

Hi, ive been looking into this and ive noticed on Heads, the are called 10bolt and 14bolt heads? How could I tell the difference?

 

[jimbro1000]

No joking aside - count the number of bolts...

It really is that obvious - the head bolts are a little obscured where the cam box extends back over the edge of the head.

 

[razmataz09]

Is it really that simple.. why are they changed then ?

 

[jimbro1000]

The head bolt arrangement went through 3 phases.

The original head bolts (10 of) on the 1300 were fine for the 128 but in the X1/9 where the engine bay tended to get a bit hot Fiat finally decided they needed more torque to keep the head flat. Somewhere around the time they switched from the 1300 to 1500 engine the headbolts increased in diameter, allowing a higher torque setting and more consistent retention of torque - the move also included a switch to stretch bolts which unfortunately wasn't documented very well resulting in a lot of blown heads after an initial failure.

The move didn't fix the problem though and about halfway through the 1500 production life they decided to add more bolts - the extra bolts are thinner and just used to provide some tension on the head where it is vulnerable.

The 14 bolt head was retained throughout the remainder of the life of the sohc engine (in Europe that is the Punto GT3 as far as I know but production continued elsewhere for some time).

 

[razmataz09]

Well thanks alot, well ill have to have a look?

 

[Maigretnz]

Weber vs Dellorto copied from Lotus site (I have Esprit with Dellotos on it.)

Once set up, there's probably little difference between the performance potential of Weber DCOE and Dellorto DHLA carbs; however, they're not simply different flavors of the same taffy. There are differences between them, and for my money, I prefer Dellortos. I'm not trying to start a debate. If you like Webers, use them.

Dellorto calibration parts, like jets and mixture screws, offer much finer resolution. Weber Main Jets are available in size steps of five (130, 135, 140...) while Dellorto's are available in steps of one (131, 132, 133, 134...). Same with Idle Jets, Accelerator Pump Jets, etc...

The Weber Idle Mixture Screws have blunt tapers and coarse threads, while Dellorto's have long slender needles and fine threads. Then later, the "E" models (40E & 45E) got even longer tapered needles and finer threads. Weber mixture screws usually end up adjusted about 1 1/4 - 2 1/4 turns out, while Dellorto screws end up 2 3/4 - 3 3/4 turns out.

Overall, it's much easier to sneak up on a very exact mixture setting with Dellortos, while you just sort of take big steps with Webers.

The Weber progression circuit often has only 2 or 3 holes, while Dellortos have 5 or 6. The Dellorto 6-hole progression is a Lotus development for their own models which Dellorto later adopted across it's own main product line.

The 6-hole setup gives the Dellorto a much smoother progression off-idle so the carbs depend less upon a heavy shot from the accelerator pump. The Weber, on the other hand, uses a big pump shot. So much so that Weber carbed engines often deliver significantly shorter piston ring life compared to their Dellorto/ Stromberg counterparts due to the Weber pump shot washing down the cylinder walls all the time.

The Weber accelerator pump's piston runs in a bore machined into the body. It's metal to metal, is subject to "blow-by" do to clearances, tends to wear over time, and the bore can't be repaired. On the other hand, the Dellorto diaphragm pump has no blow-by and clearances don't wear with use. Then when it does get old, the pump is easily rebuildable back to 100% spec by simply replacing the diaphragm and gasket.

Weber's are more prone to leak. I'm not saying that they all leak, just that they're more prone to leak. I have three Lotus engines with pairs of DHLAs, and they "never" leak, and they don't smell of gas any more than is typical of a normal carb (ie, vented float bowls). The Webers in the other car are always having leak issues and the car wreaks of gas.

Someone I know at Lotus Cars once told me switching to Dellortos was Lotus' answer for solving persistent fuel leak issues.

Regards,
Tim Engel