Dual Carb Mania in my garage:

[thechadzone]

I finally got my factory dual carburetor manifold from eBay.it, and it came with two Solex carburetors that are mostly complete, but are "parts carbs". My old man knows the Solex P11 carbs very well from his various Porsche 356/912 motors that he's been through back in the day, and he's optimistic that between the factory Fiat parts carbs and the Porsche/Solex P11-4 carbs that I just bought,(Good usable carbs for $175) something can be easily worked out. I trust him, but he hasn't looked at any of this stuff yet.

I know from childhood that the Porsche Solex has its throttle bodies on opposite sides of its carbs to work with the Porsche solid linkage bar that spans the 18 inches between the carbs. The Fiat carbs have their throttle bodies mating to each other in between the two carbs when they are placed on the super kick-ass waffle top manifold.

SO, can I swap out the carb shafts & linkage hardware from the Fiat Solex and put it on the Porsche Solex? Also, I see that the chokes are different between the two Solexes. Is there something that can be done about that?

I'm generally a Weber kinda guy, with a 32/36 DFEV currently on my '69 124AS, and a Weber DCOE set-up on my Alfa. I've read the arguments for and against Solex, but I think I still think my old man is the smartest man on the West Coast... Still, I'm now into this $432 including the rebuild kits, and I'm hitting the ceiling of how much more I can spend...

[manoa matt]

Chad,

I have these carbs, and the waffle manifold but have not installed them yet. I also got a super deal that I could not pass up, paid for the carbs and manifold what others have paid for the manifold itself.

However big differences between Fiat Solex carbs and Porsche/VW Solex carbs. The Fiats are P11-6 and the Porsche is P11-4. The Fiat P11-6 Solex carbs are an almost direct copy of Weber IDF carbs. The waffle manifold will take Weber IDF carbs and the Solex P11-6 carbs. Solex P11-4 carbs will not fit on that manifold without adapter plates, the hold down bolt spacing is different. The adapter plates are aviable on ebay or porsche parts carriers. Many guys with prosches have switched their solex carbs to webers for several reasons, parts avilability being the principal, tuning and performance are other reasons.

The big problem Solex carbs have is that the throttle shaft and shaft bushings wear out. Also the throttle butterflies tend to cut into the throttle bores from constantly opening and closing. Take the carbs off the manifold, open the butterfly and look at the condition of the bore around where the butterfly flap closes. If you see a deep ridge then if will adversely affect performance as air will leak around there and when you try to accelerate. A large gulp of air will get forced in from the not so smooth transition and upset the jetting.

I have only found one place on ebay that had the correct rebuild kit. If you bought a rebuild kit for the P11-4 carbs then it won't work. The ebay store is "Empi weber outlet" The kit will come with the necessary parts to rebuild both the p11-4 and p11-6 carbs, and you just throw away the P11-4 parts. I just checked and could not find the store or the rebuild kit. Search for "Solex 40" I can also give you the original ricambi part number off the box and you may be able to buy it direct from Italy.

The solex carbs are simpler in that they don't have as many jets, thats a good thing and a bad thing. The jets are hard to come by if you can find them. There is an ebay store in europe that carries them: http://stores.ebay.com/ALFA1750S-CARBUR ... ARTS-STORE I believe they are for the P11-4 carbs, but they should be the same as the P11-6 jets in terms of thread pitch.

I've talked to a few air cooled engine guys who are very knowledgable with both weber and solex carbs for Porsches and VW's One option is to buy jet drill bits and drill out your current jets to the size you need, however if you need to go down in size you will have to solder the jet shut then re-drill it.

Check the forum archives for the accelerator linkage setup for Weber IDF carbs as it will be the same. There are several setups that will work well, but usually the simplest is the best. Ace Ventura came up with a good one. Also check Mirafiori.com for links to Weber IDF carb linkages and setup.

Send me an email and I can provide you with some info on the carbs and pictures of accelerator linkage setups. matt.scarton@gmail.com

[manoa matt]

Chad,

Since you are going with the Porsche P11-4 carbs, the rebuild kits are readily available. Also parts for the P11-4 carbs are more prevelant due to the longer durration of the production run for those carbs. The Fiat solex carbs were only poduced for Europen Spec Fiats, and the production run may have been as short as a few years or even months.

To mount the Porsche P11-4 carbs onto the waffle manifold you will need adapter plates similar to the ones in this link: http://www.motormeister.com/suz/carb_ac ... erkit.html However, those adapter plates are to mount IDF type carbs onto a Solex manifold. You are doing the opposite. It may be possible to switch the studs and hold down bolts on those adapter plates to make it possible to mate the porsche p11-4 carbs to the waffle manifold.

Considering you are planning on using the Fiat solex P11-6 carbs as canibals/parts for the Porsche P11-4 carbs, I would be interested in a few parts from the P11-6 carbs.

[manoa matt]

Adapter plates : http://images.google.com/imgres?imgurl= ... n%26sa%3DN

I've also seen them on ebay for a little as $45

Jet kits: http://images.google.com/imgres?imgurl= ... n%26sa%3DN

Solex diagrams and manual, click the images for better diagrams and descriptions and part numbers: http://hillmanimages.com/912/fuel3.html

[thechadzone]

Thanks to each of you for your help! I'm still waiting for the Porsche solexes in the mail, and I believe the kits I have are for them. Considering the cost of adapter plates and jet kits, I'm not sure if the Solex idea is still bargain priced, and I haven't decided for sure if I'm going to go for the porsche carbs with likely modified adapter plates and swapped out jets, or just pass the Porsche carbs on to a 356/912 enthusiast who needs them, and hunt down some decent IDFs.

Which would y'all do? Anyone got a decent set of IDFs for Chad? Am I un-wise to continue on with the P-11 4 set-up?

I really appreciate the quality of responses I've gotten on this sight, thanks again!

[manoa matt]

The hardest part about dual carbs is getting them set up and tuned properly. The mechanics of linkages, adapter plates and such are the easy part, with a little ingenuity and help of those that have gone before you.

The weber IDf carbs originally used on Fiats were 13 and 15 series carbs. New weber IDF carbs are 70 series. The differences are: 13/15 series carbs have a cold start enrichment system, have the accelerator linkages in the center of both carbs, and are jetted to a fiat motor. The Weber IDF 70 series carbs are not.

However the 13/15 series carbs are hard to find, and even if, you will need to jet them to your particular motor setup, as they were originally jetted for the 1608cc motor. Regardless of whatever carb setup you choose, you will need to get the proper jets for your application. Unless you happen to find some original 13/15 series carbs that have been jetted to a setup close to yours, rare, unlikely, and pricey.

Considering the waffle manifold has a coolant passage/heated water jacket and the current aftermarket IDF manifolds do not, the cold start enrichment is not as big of an issue if you go with the 70 series carbs. There are plenty of guys out there running with the newer 70 series IDF carbs on aftermarket non-heated manifolds with no issues.

You can get a good deal on some Weber IDF's if you find some used off a VW guy. They will probably need to be rebuilt, re-jetted, and modified to link in the center. If you want to pay a bit more, you could get some new Weber IDF's from Pierce manifolds that are already jetted and center linked.

There is no reason why the Porsche Solex P11-4 carbs won't work. You just need to overcome the adapter plate issue. If you are handy, or can employ some of your father's knowledge, making those plates should not be to hard. Aluminum, Phenolic, or Derlin would all be acceptable materials. You could even make some simple molds and cast them out of JB weld or resin, then file and shape them to the finished dimensions.

You already have the accelerator linkages from the Fiat Solex P11-6 carbs to link them in the center, You may only need to shorten the throttle shafts slightly so they can sit close enough together. Even if you go with modern Weber IDF 70 series carbs, you will need to do the same modification to get them to link up. Others on this forum or Mirafiori.com can instruct you on the specifics of this procedure.

That only leaves the jets for the Solex carbs. The Porsche Solex P11-4 carbs most likely have smaller jets sizes compared to what you would need for your motor, so the cheapest option would be to drill out your current jets to meet the needs of your motor. If the Solex P11-6 carbs came with jets, then you have two sets of possible jets to work with. As stated earlier, whatever carb setup you go with you will most likely need to jet it to your particular motor, so you should plan on the cost of jets.

Chad, I'm still interested in getting my Solex P11-6 carbs to work for me, as the carbs I have are pretty good, but considering the rarity of these carbs, having some spare parts or cores is a good idea. If you are not going to use the P11-6 carbs then I'd be interested in buying some parts or the whole things to help you offset your investments.

If you rebuild the Porsche P11-4 carbs with the kits you have ordered, sell them on ebay, and I buy the Fiat P11-6 carbs from you, then you should have enough to buy some Weber IDF's. I've seen those Porsche carbs go pretty high, especially if you advertise as rebuilt and ready to bolt on.

In my opinion, you got three options: Make the Solex P11-4 carbs work, (cheap with some work involved). Rebuild and sell the P11-4 carbs, get some Weber IDF 70 carbs and make them work, (cheap with some work involved). One stop shop at Pierce manifolds with carbs that bolt on and go, jetted to your motor for a "premium" price.

matt.scarton@gmail.com

[Tappy]

found this on ebay :http://cgi.ebay.com/ebaymotors/Fiat-124 ... 240%3A1318




you can see dual weber idf's 40 13/15 pop up on a regular base on ebay , also check ebay.de !