Setting up IDA's for a stock /6, jets, and so forth Options

[krk]

Folks,

I picked up a set of IDA's in good condition that were set up for a 2.8 (maybe an RSR?) -- anyway, the IDA"s on my /6 have throttle shaft issues, so I figured I'd just swap some parts back 'n forth to get the correct setup for my stock 2.0L /6.

Turns out my original IDA's weren't exactly stock either.

There are several parameters here.

Idle jets are currently at 55 on both carbs. (stock is 45) I'll be using 55 initially.

Mains are 125 on my current set, 155 on the new ones, stock is 105. I'll be using the 125's.

Emulsion tube on mine are F26's (same as 911L), and on the new ones they are F3's (911S). The originals used F1's. I've no clue which one I'll use -- if I'm lazy, I'll leave the F3's in there.

Air correctors are 180 on both IDA's. Original's used 170s. I'll use 180s.

Pump Jet is 50 everywhere.

In the picture you will see two different auxillary venturis -- the shorts ones are stock /6, and the tall ones I've not seen before. No clue what to use.

Lastly, and I've not got this far as I have to cut wires, but from an eyeball estimate, the actual venturis on the originals were quite a bit more restricted. I'll pop both of them out shortly to see what they are --- i'll use whatever is closest to the manual I guess.

Comments welcomed.

kim.

This post has been edited by Gint: Feb 8 2004, 10:47 AM

[d914]

I have extrs 32 and 34 venturis and extra 135's and 160's for mains.

Swap or buy the 155's.

Looking for a different emultion tube. Have f3's need a f9 or 23 I think???

[J P Stein]

I ain't got all the answers here, but a few.

The tall secondary venturis improve mid-range torque in an engine with a lot of cam...or so I'm told.
Prolly won't do much for a T cam/motor.

The primary venturis for a stock T motor were 27mm, IIRC, and the carbs should be IDTs. Some folks switched to 30mm for more top end. The f27s tubes will prolly work fine...thas bout it from me.

[krk]

Thx for the data!

The IDA's that came with the car are clearly not the original's (not IDT's), so I"m not surprised to find things that a different from stock. My main goal is to have a set of carbs that should be reasonable once I put the alternator (and all the other crap) back on the car. (it started off as a quck morning project while the air temp got warm enough in the car port -- now my house smells of gas. Sheesh)

I believe the current engine has a stock cam (or something near stock) so I'll use the stock secondaries (damn - means I have to take both sets apart... ah well.. it's a saturday)

Your recollections on the stock venturi's agrees with the P manual. I have a choice between 30's (just took one out of the original ida's) or the new ones, which are unlabled, but clearly larger. I'm thinking the 30's make the most sense.

For Emulsion Tubes, I'm picking twixed F3's and F26's (dunno if there was a typo in your post) I'm leaning to the F26's since I have to dismantle all anyway -- this engine is not an S engine.

kim.

[TimT]

definately uise those tall secondary venturis, they help out alot in midrange and transitions,

30 mm main venturis
125 mains
180 air correctors
F3 emulsion tube


it should work well
you may have to do some plug cuts and adjust the size of the mains..

[krk]

Hey Tim, Thx for the comments!

That sounds like a doable combo.

Just to keep the thread up to date, the new IDA's have 34 venturies (the last one I took out had a number stamped on it) The firs t two came out easy, and the next one was not happy about leaving home.

I can almost assemble one carb. wheehoooo.

kim.

[krk]

As I chug along looking at the build list, there is another small question -- the intake manifolds could use a touch of paint -- how hot does it get that close to the engine? Any paint recommendations?

kim.

[seanery]

mine haven't been painted, just clean cast aluminum. You could send them out to Jet-Hott and get them coated.

[krk]

Seanery,

Heh. (IMG:style_emoticons/default/laugh.gif) I'm assembling. I can spray them now. Or just put 'em on. I have several different rattle cans around...

kim.

[mskala]

For a totally stock engine, I'm using 55 idle, 120 main, 170 air, tall secondary,
30mm venturi. I did test the 125 using my data collection stuff and it made
zero difference. I got most of my numbers from Jon Lowe's recommendations,
but I went to 170 air since it smoothed out something or other, can't remember.

Oh yeah, F1 tube. F2 and F3 were originally for the E and S, I believe. F26 is
listed in my old Clymer book as original (maybe in europe?). F1 was original.

[campbellcj]

Well I think I finally got my 40's sorted out today ! (IMG:style_emoticons/default/boldblue.gif)

Richard @ PMO was a great help and supplied some parts including his sweet AN-6 solid fuel bars with 2 day turnaround.

My engine is a factory -6 built to 2.2S specs, except that the heads are a "mystery" and may well be stock 9146/2.0T.

The main problem was just the setup of the carbs. I wish I would have checked that out sooner -- knew it was running very rich but figured the jetting was way off and I didn't want to deal with it at that point esp since rich = "safe". Well, the PO had the mixture screws about 6 turns open (baseline is 2 turns)! And, the idle jets were 55's but I found 1 50 and 1 45! (They may have been reamed out, I dunno). Air idles were too far open also, I think. Venturis were a bit too large for this motor too; they were 34's at least.

Also I tweaked the linkage rods to finally eliminate a tiny bit of preload that was causing the idle to wander; sometimes it would come back down nicely, sometimes not.

Lastly Richard suggested going to a click or two hotter plugs, so I went to a BP7ES (I had 8's which are very cold.) I have a set of BP6ES's here too but probably will not need them. BTW www.sparkplugs.com is pretty cool -- huge selection and very prompt delivery.

Anyways, this is what I have in 'em now and the car is running way smoother and with noticably more pull and sharper throttle response.

32 venturis/chokes
4.5 aux venturis
180 air correction
F26 emulsion
55 idles
130 mains

This is the 2.0S setup except for the F26 vs F3 emulsion tubes. Richard said I should try those if the car wasn't happy with the F26's but I am not seeing any reason to change at the moment and am not sure what the actual diff would be?

[krk]

marc, thx for the details on your setup. Hopefully, this means I'll be close (lol). Do you have a pointer to Jon's stuff?

kim.

[krk]

Chris,

Thanks a ton for posting. I can't wait to have problems from a running 914 (IMG:style_emoticons/default/laugh.gif), but it is good to hear of BTDT! As a status, I've moved all the internal bits over, and this evening, I'll move the jetting bits over. Tomorrow, I'll move back to assembling the grotty bits under the fan shroud and as long as I don't screw anything up, we'll have something to talk further on!

kim.

[campbellcj]

Since we are on this subject, can somebody take a crack at explaining what the emulsion tubes do, and what effect a change has on the tuning?

I am starting to get a vague grasp of Weber operation after reading several write-ups, but the emulsion tubes are still pretty mysterious to me.

TIA,

[krk]

I'm with you -- these are largely mysterious things to me as well.

I can certainly write up the bits that I have. Doesn't mean I necessarily understand all of it tho -- there isn' t a lot written that I've encountered so far and I don't have much btdt of consequence.

They are mostly reassembled -- the last venturi was a bit of a pain to get out, but the rest has gone smoothly. Some small bits to go, and they are ready for install. Tomorrow should (knock on something somewhere) see it all back on the car. (IMG:style_emoticons/default/laugh.gif)

kim.

[Carl]

As I understand it, the emulsion tubes slow the flow of fuel to the main jets by bleeding air into the chamber that feeds the mains. The air mixes with the gas making it less dense. As engine speed increases, the fuel level in the chamber is drawn down thereby exposing more of the holes in the emulsion tubes. As more holes are exposed, more air is drawn through the holes and the engine runs leaner.

Without the tubes, the vacuum through the carbs would draw too much fuel through the mains and the engine would run rich. Why this wouldn't be solved with smaller mains, I don't know.

The number on the emulsion tube has no bearing on a measurement or size. It only relates to the experimental sequence the factory went through to make them work. For example, F1 was their first successful design, F3 was the third and F26 was the 26th.

I think I read this stuff in a book somewhere ...

Carl

[si2t3m]

Here is some info i collected about the Emulsion tubes:

Emulsion Tube Selection
-----------------------
The emulsion tube emulsifies air from the corrector jet with fuel from the main fuel jet and therefore controls the mixture emanating from the nozzle at all engine speeds with the main circuit in operation.
The controlling factors of the emulsion tube are its diameter and the location of the emulsion holes. These factors are included in the code number of the emulsion tube which is always preceded by the letter F. Unfortunately the code numbers do not follow in any particular sequence which would indicate the applicable characteristics, but the following chart shows the emulsion tubes to be wired to correct mixture faults, together with the most common types:

This post has been edited by seanery: Feb 8 2004, 08:25 AM

[si2t3m]

and a chart

This post has been edited by Gint: Feb 8 2004, 10:50 AM

[si2t3m]

and finally an interesting write up:

Emulsion tube stuff


Found this a while back when someone posted on the bird board. I kept the stuff handy for my Weber Zen!

HTH



Marc-André

[TimT]

hey!! I believe I posted that chart on the pelican thread (IMG:style_emoticons/default/wink.gif)