The Official 356Talk Forum

Weber IDF 40s (Spanish) on my engine (1967 912 but virtually a S90/SC) have linkage that works fine with the standard linkage, just like with Solex P II 40s, that push down on the inside side (towards engine mid-line) of the carbs.

I just ordered, received new IDF 40s -- version K 291XE (40 IDF 70), supposedly for the 912 (356 S90/SC) engine. BUT the linkage on the carbs requires a mechanism that pulls the carbs linkage arm INWARDS; the linkage arm stands up vertically from the throttle axis.

Also, the old carbs on the engine (Spanish Weber IDF 40s) have different linkage on the left-side and right-side carbs; the new (K 291XE) both carbs are identical in linkage set-up, but with linkage arms at both ends.

I know it's not any 356 SC/S90 vs 912 difference. I knew the Solex P II 40's and the linkage well, which is the same on this engine -- having some decades ago rebuilt a set of Solex carbs (on a 1968 912 in Germany), and having messed around with the Solex's for 40 years on the 1961 356B Cabrio I used to drive.

Anyone know availability of finding linkage parts to configure the Webers correctly to be linkage "plug-compatible", so to speak, with the native Solex P II 40 linkage?

The new carb vendor sold them as specifically for 912(356) engine; if they can't fix this, I'll have the credit card company reverse the transaction on the basis of fraudulent assurance of compatibility.

Thanks for any info...

P.S. When I sold the 356 Cabrio, after a while a sort of homesickness set in, and I bought the 912 (for 1/4 what the 356 sold for) -- same engine in a body rather better engineered, much easier to work on for a person with long arms.

Consider making the sort of arms that you want. Someone may already make them. Don't be nasty to vendors.

Robert Vaughan wrote: Consider making the sort of arms that you want. Someone may already make them. Don't be nasty to vendors.

Doing more research, I've found that the photograph on the vendor's website of that Weber 40 IDF 70 I chose to purchase shows linkage that looks like it'd work fine (on 356 S90/SC or 912 engines), i.e. linking up with the descending rod by an arm on the carb that's oriented horizontally, to the inside (towards mid-line of engine) of the carb, so that the throttle is opened by pushing down on the carb's linkage arm -- the standard setup used for Solex P 11 40s, and works with the old Webers already in the car.

So I was not sent the items as advertised on the website and during the sale. They also, in the process, asked me to specify the exact brand, year, model etc., assuring that the item would be suited to 1960's Porsches.

Known available variations in the linkage of the Webers to fit 356/912 are apparently readily available (as in the photo). What I was sent was the wrong item, can't run on the Porsche engines short of making major alterations to the standard throttle linkage (likely, these days, $100s).

I've communicated the details to the vendor, and would expect him to understand, seek to supply those relatively minor parts (couple of two-piece items which bolt to the throttle shaft). If he can't do that, then the sale must be rescinded, as it was based on false representation of the product.

Surely I could go to any of the umpteen hi-tech mechanical engineering firms here in Silicon valley and have parts made, for $100s (not for the metal but for the hour or two of precision engineering).

My OP (opening post) here was intended to check for possible known sources for those parts, which should cost in the neighborhood of $5-$10.

I hope this helps....

If they sent the wrong thing, take it up with the vendor. If they fail to satisfy you, use your credit card service to get satisfaction. You say you have a 912. Is the carburetor vendor one of the vendors listed here on the Registry?

I've recently been trying to smooth out the running of webers and the associated 009 distributors that seem to follow them on a 912 and a 356SC. Neither car is happy with this set up and I can't understand why folks do this conversion when the stock carbs and distributors can be repaired.

Fred, if they HAVE to have the 009 distributor, send it to John Jenkins in San Diego and he can update it to give you an acceptable ignition curve. (At least he used to do that.....) He's listed in the vendors and works through an arrangement with 356 Carberator Rescue.

I'm running Spanish Weber IDF40's on my '65 356 C with 022 distributer (actually a 123 Ignition distributer with 022 curve) and 1720 kit and am quite happy with them. Yes, I've been sorting them for a number of years but persistence seems to have payed off. I'd like to compare them to a set of stock Zeniths but my car came with the Webers and the cost doesn't warrant the change over.

1: correction: in the subject title, "K 291XE" was incorrect. What I'd actually ordered was a pair of 40 IDF carbs model "18950.138", supposedly OK for 356/912 -- but not really...

2: Tentative resolution of problem: I figured out that the Redline kit "K291 XE" has, at least according to the pictures (found at multiple sources on the internet) IDF 40s with the correct 356/912 linkage -- namely push-down connections on the inside (towards engine mid-line) correctly aligned for both left and right carb assemblies. Reached agreement with the vendor to order the K291 XE kit and return the 2 "18950.138" for refund. Gave up arguing with him that the 18950.138s he sent didn't match the photo on his website. (That vendor is not in the 356 Registry list, fortunately.)

The downside is that I could've gotten the K291 XE kit from an out-of-state vendor in the first place for $699, and saved having to put-out for California sales tax (ca 9.5%). Several vendors (including the one I used and this out-of-state one) offer free shipping, but some in California add both shipping and tax -- an extra ca $100 cost and often on top of a base price more than $699. Learning curves can be expensive, as we all probably know in dealing with vintage Porsches.

3: Other interesting lessons from my research:

An article "The Weblink - Upgrading Dual IDF Carburetor Linkage - Reprinted from VW Trends / December 1998" at:
http://cbperformance.net/pdf/WeblinkDualIDFupgrade.pdf

An informative summary of the history of Weber carbs and VW/Porsche usage. It turns out that previously Weber offered IDF 40s with totally correct left-right mirrored configurations -- plug-in compatible with the standard 356/912 linkage system. Then Weber discontinued that (sometime before 1988), and only delivered "right side" carburetors. (Apparently Redline does their own modifications to compensate.) The article also includes detailed instructions, with abundant photos, of how to mess with / adapt IDF 40s linkage.

Apparently these original perfectly 356/912-configured Webers are what's in my 912, so worn-out, however, that I decided to replace them rather than attempt rebuilding with the risk of finding problems that would force replacement in the end. If the tentative solution (above) works out, I might offer this original set on eBay in case there's someone out there with the time and energy to try to fix them.

Also found a source, from Germany, for various possibly relevant parts, e.g.:
https://www.ebay.com/i/332377904141?chn=ps
and much more at:
https://www.ebay.com/sch/vergasermanufa ... pg=&_from=
They even offer IDF 40 kits if I ever want to soup-up my 1973 VW Camper-van -- for $1300!

Meanwhile, thanks to all here for their various interesting perspectives on the problem. Will look out in case the problem pointed-out elsewhere in this forum crops up -- where the difference between left and right back-forward displacement of the carbs might negatively affect performance of the linkage system ...

Chris Macie wrote: where the difference between left and right back-forward displacement of the carbs might negatively affect performance of the linkage system ...

The solution to that is shown in my 2 pictures above, 2 additional levers and one ball facing forward and 1 facing back each spaced equally 1/2 of the total offset at the levers. Failure to do it this way will likely cause binding of the down rods and/or sync imbalance.

C J Murray wrote:

Chris Macie wrote: where the difference between left and right back-forward displacement of the carbs might negatively affect performance of the linkage system ...

The solution to that is shown in my 2 pictures above, 2 additional levers and one ball facing forward and 1 facing back each spaced equally 1/2 of the total offset at the levers. Failure to do it this way will likely cause binding of the down rods and/or sync imbalance.

Thanks, that looks to be a better solution than the one I was referring to -- using a single long extension just on the left side, as pictured in a post you wrote under topic "Answer to a Weber question" back on "Thu Mar 28, 2013 10:20". Using two lever extensions, each 1/2 the distance discrepancy, would seem less risky (e.g. of distortion bending) than the single long extension on the left.

Where did you get or how did you fashion those extension lever pieces? I was able to find a website for "Classic and Speed Parts" that you mention in the 2013 post, but couldn't readily find such levers.

btw: another curious discrepancy among Weber configurations... Attached two photos of the Webers in my 912, showing a different configuration of the coil springs, which doesn't require hooking to the air-filter assemblies: (Can't figure out how to get these photos to show-up here other than clicking them to download. The original .jpg files from the phone camera were a bit too large to upload, so I screen-captured them to .tiff files that were smaller.)

These should work but I am looking for what I have. I have seen the springs done that way but it does not work nearly as well.

http://www.carburetion.com/Products/Pro ... =DELCB3406

For the way the lever sweeps the more upright position springing is much more consistent.

Much cheaper!!!!

http://vwparts.aircooled.net/Carburetor ... cb3406.htm

C J Murray wrote:Much cheaper!!!!

http://vwparts.aircooled.net/Carburetor ... cb3406.htm

Thanks.

How about the tubes / rods to insert between the carb's lever and the ball-joint at the bottom of the descending linkage rod, to equalize the back-to-front distances? Did you fabricate or buy those?

Do you think this part would do the job? http://vwparts.aircooled.net/Heim-Joint ... cb3395.htm

They are easy to fabricate.