However if you decide to convert to fuel injection, there are a couple of choices.
As you mentioned the later X's factory FI system will swap onto your engine. Many have done it; it is a bit of work but certainly possible and probably the most cost effective route. Look for the numerous threads on Xweb that cover how it is done.
Another option is to retain your carb manifold and install a aftermarket EFI for two barrel intakes. Effectively it replaces the carb with a pair of injectors and throttle plates, making it a throttle body injection. Holly makes one and I believe there is at least one other. The downsides are cost (definitely more than getting a complete used Fiat system), issues with installation (they are generic and not designed specifically for this application), setup (it won't necessarily be the correct injectors and controls), and there is really no way of knowing how well it will work (I don't believe anyone has ever done it).
Yet another option is to build your own system from scratch. There are throttle bodies that replace Webers and could be used on a SOHC manifold for dual Webers. Or use the throttle bodies from modern street motorcycles. Or use a race style set of slide valve throttle bodies from one of the specialists that make them for track applications. Any of these will require that you also develop a ECU and related components to support the system. Likely the most expensive and most difficult route to go.
I'm willing to bet you can find something on the internet describing how to get cheap used parts from junkyards and cobble together something. I won't even discuss that any further.
So I think getting the FI system from a later model X is your best choice. You can either keep it completely stock/original or you can do some upgrades to it (e.g. aftermarket programmable ECU). By the way, I seem to recall seeing somewhere that the "programmable EFI system" sold by one of the vendors uses another ECU other than MegaSquirt. But I could be mistaken.
As Karl said, rather than switching to FI you can get a better carb. Personally I feel EFI is much better than any carb. But that is only my opinion. A carb swap is certainly much easier and less expensive to do.
Have you heard of Remflex? Graphite gasket, crushes when installed, accepts minor deformation (up to 1/8").
all one piece, they have an X1/9 fitment
http://catalog.remflex.com/FIAT_MANIFOLD_HEADER_GASKET_p/37-001.htm
I have one, works like a champ!
Its sad to hear your carb set up is not working out. I have almost the exact same build as you, so we will see how it goes. It sounds like your biggest issue is the manifold itself. It is aluminum so is fixable. Perhaps with any lessons learned you could remove the top plate and modify/remake it as needed, reweld? This would be much cheaper than any EFI conversion.
On another note, I recently made a full order for LEDs inside and out. I can let you know how it goes once they arrive and I have a chance to install them.
Andrew,
Thanks for the update. Would love to hear how the LEDs workout for you. Looking to do the same to mine. Yes, you have the same setup from FiatFactory I believe. The issue with the intake is not just grinding it flat again, but getting too thin, then also the exhaust manifold has to be refinished as well. To help with some of the issues with any carb, I'm thinking an electric fuel pump, at least the bowls will be full every time I turn the key.
Do you have a return line from the carb to the tank for over pressurizing the carb? I have a little T in my line. I wish I could modify the top of the carb to make a splitter embedded into the inlet like the stock carb does. Perhaps remove it and see if that helps.
Or you could use a ignition cutoff switch to disable starting and allow the fuel to prime before starting. I need to put one in for an insurance break as well: active disable device.
Hi Willy, couple of thoughts after reading your comments.
First, if you decided to convert to a Fiat X1/9 FI, you do not need to go MS2. You can use the original stock ECU and all other components. That is actually more likely to be trouble free and much easier (and less expensive) to do. In fact, if you buy a complete used X1/9 FI setup from someone then it should contain everything you need for a lot less money than the Holley system. It will require a couple of minor alterations as others have mentioned. But so will the Holley EFI, and even your carb setup from the sound of things (more on that in a moment). As I understand it, the Holley EFI is designed for American two barrel conversions and will not be a direct replacement on your Fiat. I'm not certain what base mounting bolt pattern you now have on your modified intake manifold, but most of the American vehicles with "Weber" type carbs use the DGV derivatives, which are not the same bolt pattern as most Webers that we deal with. Therefore it may not be so easy to get an adapter plate to fit the EFI to a Fiat manifold.
Regarding your issue with the carb intake manifold not sealing to the head. I'm of the impression that the major amount of cutting, welding, and machining that is involved in converting the stock manifold to rotate the carb 90 degrees will ruin the manifold. Too much heat, etc, to keep it anywhere near straight...even with machining. Again, that is just my opinion. But consider that even the stock (unmodified) manifold can be difficult to get flat. I've dealt with this on both carb and FI Fiat manifolds. They are old, been through many heat cycles, the engines are prone to overheating, they have been torqued (and over torqued) MANY times, etc, etc. If it is machined enough to make it flat and true (two different things) then you are left with thin mounting pads. And with the (undesirable in my opinion) shared mounting between the intake and exhaust manifolds, you will still have leaks due to uneven torque on the studs (unequal manifold thicknesses). Yes the exhaust manifold can also be machined to make its pads thinner. But keep in mind the exhaust manifold is typically even worse in terms of distortion and therefore more difficult to get true and flat. So you will be going in circles trying to make both fit correctly. As if all that wasn't bad enough, I've also discovered the head mounting surface is often not flat or true. So still more machine work is needed once the manifolds are finally made right. "Magic" gaskets will help in minor cases, but with your modified intake manifold I am skeptical.
And do not forget. If you install a Holley EFI on your manifold it will still have the same leaking problems you are now facing. But as I said, the stock Fiat FI manifolds are not any better in terms of sealing. So converting to Fiat FI may not be much better. Although any other intake manifold may be better than the modified one you now have. One option might be to buy a new Weber style (e.g. Aqualti, etc clone) intake manifold from one of the Croatia suppliers, and keep the carb you have.
Any minute you will see replies pop up saying they have never had the manifolds leak, the stock Fiat components never fail, this is completely unfounded and simply not true, old Fiat engineering is the best in the history of the automobile, I will go to hell for saying such things, etc. And I'm sure they are all correct. But I am offering my personal experiences. I think before you decide to spend any money on any conversion, it might be best to find out exactly why your intake manifold is not sealing. Is the head mounting surface flat and true (as measured with proper machinist equipment)? Is the intake manifold distorted, excessively warped, or otherwise unrepairable and therefore not usable? How do the intake and exhaust manifold mounting pads compare in thickness AND surface angles (are the two halves of each nut landing true, parallel, and flat to each other)? Are the mounting studs, thick washers, and nuts correct and properly tightened?
Please do not take any of my comments as implications that you have not done any of this or that you do not understand these things. I am simply trying to go over all of the things that I think might be considerations in the hope of helping you find a resolution to the problem. That is the end goal...to get your engine fixed.
These guys seem to have this nailed down: https://www.classicfuelinjection.co...ath=113_110&osCsid=se0e86j43p71s7sueinik7clr2
Willy, thanks for explaining the details...I now better understand what you have. Sorry if I might have missed any of those details earlier.
Sounds like you are on a good path. Hopefully your manifolds and head surfaces are now true, that's a huge factor. I agree the mounting arrangement of these manifolds isn't ideal. But with enough effort it should be able to be made workable.
About prices. The Holley EFI is actually less than I thought. Somehow I had the impression it was closer to $1700-2000. On the other hand I think you can get a good working, complete Fiat system for under $1000 from guys on this forum. So it may not be that big a difference either way.
I agree it would be very interesting to see how the Holley system works on these engines. Keep in mind there are several factors about that design that may make it less than ideal. The size of the injectors in it may not be correct for a small 1500cc engine (think of the size of a 4L Jeep engine). The arrangement of having the injectors at the manifold mouth (throttle-body injection) instead of at each intake port on the head (factory FI) isn't as efficient. The mapping included with the ECU might have assumptions that don't fit these engines. The included sensors might not be of the appropriate range for this application. What inputs does it use for crank position, and is that included? I don't think it controls spark, but neither does the stock Bosch system. And installing it onto the Fiat manifold and throttle linkage may be a challenge. Also think about the intake manifold design; with the Holley on a carb manifold you have unequal length runners that are not great flowing, compared to the FI manifold's plenum and equal runners. But many of those factors might not be that bad either; it is just a big unknown, perhaps you will be the one to find out. If you wind up going that direction I can suggest a guy that can make the adapter plate to fit the Fiat manifold.
I agree the old Bosch FI system seems like a step backward, but it isn't that bad either (especially in comparison to a carb). Keep in mind it was specifically designed for these engines (unlike the Holley system). Many of the principles and design parameters that went into it are still used by some vehicles today. It is a fully electronic controlled injection. If you get to understand how it all works and make sure everything is functioning correctly, then it is very reliable and efficient. But there is always room for improvements, and those can get more costly as you mentioned previously.
I'm curious to see how the graphite gaskets prove to work. I've heard mixed input about them in general. They seem to be great for certain applications but not good for others. In the case of the Fiat SOHC it is a mixed bag, especially with the shared manifold mounting arrangement. So I'm really not sure. I am planning a turbo SOHC engine and would like to find the ideal gasket for that.
Speaking of gaskets, there may be some reasons why the ones you've tried so far haven't worked so well. I've found that the positions of the ports going into the head and coming off the intake manifold do not tend to align well on these engines (I'm sure that can vary). And there are places around the intake openings that don't have a huge amount of flat surface to work with. Some gaskets have oversized holes to accommodate this, and some do not align that well. So it can be possible for there to be a very marginal sealing area in spots...especially if 'all of the stars do not align' perfectly. Add in the mounting arrangement we discussed, and potentially inferior gasket materials (depending on the source), and you have a recipe for leaks. By the way, the UnoTurbo gaskets are designed for a FI head, so it has really big openings to clear the "scallops" on a FI head. That could have been a potential issue, but really should not have been.
Great discussion.