Carb dilemna

[georgeramos]

So i was going to buy a DFEV but wanted to keep my manual choke capability. The only option at Pierce was the DGV. i bought it and received it today BEFORE researching it here on the forum. So has anyone successfully tweaked the throttle cable/linkage to make it work with the counterclockwise rotation of the carb linkage? It sounds like a bit of a hassle. i may simply exchange it but im not certain how to hook up the electric choke. My car is a 71 with stock components.

Thanks

George

[manoa matt]

You can simply remove the linkage from the carb throttle shaft and flip it upside down. It would turn a push into a pull or a pull into a push. That is provided there is nothing in the way.

[georgeramos]

Hi Matt, id the shaft you mention on the carb or part of the car? I would assume the latter but just want to be sure...

thanks

George

[manoa matt]

Your current carb should have a linkage ball attached to the primary throttle shaft. Sitting in the drivers seat looking at the carb, the linkage ball is on the upper left, and the linkage pulls it toward the engine/right. Take that linkage ball off the carb and install it on the DGV but orient it so its hanging down and to the left. The linkage will still pull, but since the ball is now below the axis of rotation it accomidates the counter clockwise rotation needed for the DGV.

One issue will be when you flip the linkage ball it will not be hanging down to the left, but hanging down to the right, which means you'd need to order a new linkage ball from pierce that orients it to the left.

The other issue will be the ball is in a somwhat different spot and whether the stock linkage with all the little rods and pivots can be adjusted to accomidate the new location of the linkage ball.

Alternatively you could swap the DGV for a DFEV and remove the electric choke and install a manual choke.

Try posting a picture of the current carb on the car and include in the picture the accelerator linkage with the rods and such.

[georgeramos]

I see it. sounds simple but "its always somethin" the hole in that lever is the "squared" type. It is a)smaller than the one on the new carb and b) facing the wrong direction... I can probably just drill it out round and maybe use a lock washer... does that sound like a safe plan?

thanks

[manoa matt]

No, don't drill it out. The semi square hole is imperative and must be a tight fit or there can be radial play between the shaft and the linkage(slop). I've made a few linkages by drilling and using tiny files to make that square hole. If its even the slightest bit too big the linkage ball will rotate a few deg. In either direction before it starts to turn the throttle shaft. If you tighten the nut too much, or even tight enough to clamp the linkage from moving, it can pull the shaft and the throttle plate into the side wall of the throttle bore, which would cause it to bind. That nut should be snugged but not too tight.

Pierce may sell the needed linkage ball, you just need to make sure the square hole is indexed properly, they have a bunch on their site.

[baltobernie]

You have another option. The throttle linkage on early Spiders is problematic, because it uses a rod from the firewall to the carb. As the engine shakes, the throttle linkage moves, making a smooth idle very difficult to achieve. Fiat recognized this design flaw, and corrected it with a cable design using an engine-mounted bellcrank in the late-70's. My DGS and DCD carbs pull to the left like the DGV. I swapped the pedal assembly from the later carbs, which place the pickup point left of the clutch pedal. I then had a custom cable made and used Weber p/n 99007.116 adapter kit:http://jameng.com/products/images/99007.116.jpg. This is the result:





You can use your OE choke cable (not installed yet in these photos), or get a new one for $13 from JEGS, p/n 15830. If you look closely at my engine, you'll notice that the Weber adapter provides a second cable mounting point, perfect for installing a cruise control. This is a really useful upgrade on a Spider, with its "Italian driving position".

[manoa matt]

How's the DCD working out Bernie? Tuned yet? If that's the 36/36 it should go like a scalded cat.

[baltobernie]

Still tuning, Matt. Thanks for asking. Up one idle jet size helps a lot, from 47 to 50, but still too lean under light load and light throttle. Mechanical secondary, as you know, so no problema there Strangely, the 55-size idle doesn't seem to help, so I'm gonna twiddle with timing; maybe "light the fires" a little earlier.

[manoa matt]

Bernie,

I highly recommend this book: http://www.amazon.com/Weber-Carburettor ... hn+Passini

The DCD series is extensively covered, as a matter of fact its almost a manual for a DCD. Passsini also demystifies the emulsion tube system. The way he writes is sometimes hard to follow, but I've never read a book by anyone that knows more about webers, I think he knows more than some of the techs at weber. I think there may even be some tables of jetting info for a DCD on a fiat.

George, Bernie's suggestion to switch to a cable system is an excellent one and could simplify the linkage, the trick is having redundant return springs on the linkage to elimenate any slop in the cables.

[baltobernie]

Ordered it, thanks. The Braden book is helpful for the DCOE, but not much else. (Someday, when I build my Ultimate Spider... )

[lanciahf]

Bernie,

On my old spider I had a DCD and loved it.

I used the largest chokes possible, 27 on the secondary and either 25 or 26 on the primary. Is that an old new weber or one of the new "webers".

Please let me know how you like it as I was thinking of ordering one from pierce manifold. I sort of did what you did with the cable but I used the stock throttle arm with the ball. I cut the ball off, flipped the lever on the shaft and rewelded the ball. I think I had a 1/2 spacer on the manifold.

I'm glad you got rid of the DGAS carb, they are too nasty for spiders.

Thanks,
Ralph

[baltobernie]

I'm glad you got rid of the DGAS carb, they are too nasty for spiders.

Yeah, everybody but the parish priest told me the synchro 38 was the wrong carb for the Spider, but, you know, I never was the brightest pupil ...

This is a new Spanish Weber, 36 DCD 16, with 25/27 chokes, purchased from Fast Road Cars in the UK. I'm very optimistic that this will perform well on my car. Out of the box was encouraging. Cold start enrichment works perfectly. Carb is very tall, so OE air cleaner housing won't fit. The short K&N assembly clears the hood; I'll use their breather filter elsewhere. The air filter is too small to accept the breather nipple. My phenolic spacer is 1/2".

The wideband A/F meter is making this exercise a lot easier. Film at eleven.

[manoa matt]

On both carbs in question, the DGV and the DCD, the primary and secondary throttle bores are reversed from other typical progressive carbs installed on an open plane manifold. The primary throttle bore being closer to the engine as instaled on the manifold.

I wonder if this orientation will cause cylinders 2 and 3 to be rich, while cylinders 1 and 4 go lean when running on the primary throttle bore. When the secondary opens it should even things out. The reasoning being the primary throttle would dump the mixture right in front of the No. 2 and 3 cylinder runners and get sucked in before branching off to cylinders 1 and 4. Where as with the typical arrangement with the primary throttle being further away on the manifold, the mixture can drop and spread out more before being sucked into the various intake runners. A simple plug inspection would reveal this.

Bernie, I have a fitting that came with an old Bayless 1 3/4" high lunch box style air cleaner. It mounts on the side of the element and you can attach the breather hose, it's yours if you want it.

[georgeramos]

Ive returned the DGV to Pierce and will exchange i for the DGEV...

Thank you for the tips and advice. i will be paying close attention to the linkage setup when i install the new carb!

George