WEBER 40 IDF Conversion-how to-PART 1 of 3

[Sweetheart912]

The site rejected my Word attachment, so I am sending it in 3 parts. Hope this helps.

MY WEBER 40 IDF CONVERSION for my 912.

I was reading a lot of the Weber 40 IDF tech discussions on various boards, and I just completed my conversion and the car runs SUPER & idles smooth @ 650 rpm. I have a 69, stock p/c & cam, 616/40 engine. If you are running a big bore or some monster cam or such, you may need bigger jet sizes than what worked for me here.

I did some homework, and went for it, and wanted to pass on the “how it went info”. I had to fabricate a few things, and I'll pass on what I learned during this hands-on event.

My opinion is if you use a VW setup from the dune-buggy guys, or an out of the box Weber, you are essentially replacing your old Solex with a new Zenith equivalent carb. I think most people are unhappy with their Weber conversion BECAUSE most all come out of the box with 28mm venturis, 115 mains, 200 a/c jet and 50 idles. It is not enough juice for the 912, if you do the math. Wanting to approximate the Solex, I ordered the Redline Weber Kit, 40 IDF with manifold adapters, plus four 32 mm venturis, four 130 main jets, four 125 main jets, and four 60 idle jets. Also, I ordered 4 short velocity stacks (for synchrometer use later). The 200 air correction jets that come with the carb are perfect. The 55 idle jets that come with the Redline Weber’s were in my opinion a little short, but may work fine. I went straight with the 60’s.
Also, when you take the stock air cleaners off, you will need to vent the oil breather/filler can that used to pour sludge back into the 1-2 air cleaner & carb. I went to Pep Boys and bought a Chevrolet Oil breather cap made by Specter- it looks like a mini air cleaner, @ 2 & 1/2” in diameter, & its chrome and washable. Matches the air cleaners perfectly. Slip it over the breather teat, affix with a clamp, and it looks cool & is functional.

The guy who sold me the high quality Redline Weber kit was Eric, at Performance Parts Warehouse, at 800 654-2778. GOOD GUY & helped with some tech too.

FRIDAY NIGHT:
Time to get to it. First I removed all the stock vacuum retard junk - and replaced the original vacuum distributor with a rebuilt 031 distributor (a 050 would be fine, but had the 031 on the shelf). Checked timing both static & dynamic with old carbs on the car.

Timing was dead on, so I removed Solexes, all assorted clamps, and original air cleaners, hoses, fuel lines, and black tubes. Boxed the whole Solex & distributor thing up for posterity - vowing that stuff would never see light of day again as long as I owned the Targa! But I think all original stuff is good to keep, so I kept it for the next owner, down to the last washer & clamp, +2 new rebuild kits & new manifold & air cleaner gaskets & filters. Yeah, guess I’m kind of anal about that kind of stuff.

Place paper towels in each manifold throat, or cover with duct tape, or take your chances that you WON’T drop something down there (Murphy?).
Remove studs from the Solex manifolds, on the engine. using the 2 nut removal process. Scrape all old gaskets off, vacuum all around there. Also, a good time to wipe off any back or side sheet metal, check around the back of the motor for long lost tools, or junk in the air volute. I replaced the fuel filter also-why not?

I also found it a good time to change spark plugs-since it was so easy to do with the carbs off. Besides, I wanted clean plugs to refer to for tuning after driving awhile to see if my mixture settings are right. Good call, as the old plugs were pretty fouled from rich running Solexes. I used original side tip, Bosch W225T’s when I can get them; other wise Bosch W6BC is a good plug. New W225T’s in, checked all plug wires for continuity, and tightened all wire ends. All rubber seals in place etc etc, so…

OK, ALL old stuff all out & aside, ALL preliminary garage work done, then, I took out my Redline Weber kit with adaptor plates.

First, the adaptor plate: Screw in 8 new studs finger tight and place gasket, carb, washer, nut etc for trial fit on both plates. Scribe pencil line on studs to make sure you have "enough". Red loctite all 8 in using the 2 nut install process, and then let them settle.

Second, the carbs: Swap main & idle jets and venturis out, and use the 28mm's for paperweights. (I started with the 125 mains & after initial tuning; my motor liked the 130's better). Make sure all 4 air bleed screws are closed & locked down and leave them that way. Turn in the 4 mixture screws until seated, back out one turn & stop. Screw in the 2 idle screws until they touch the arms then 1/2 turn & stop. Adaptors & carbs are ready. MILLER TIME….well actually a Corona.