Weber tuning expert needed

[Norm01]

I have a 68 2.0S 160HP engine. Unfortunately it does not have the original carbs. What the engine came with is a set of 40IDTP13C. Below are the settings, just wondering what Weber specialists might think of this. The main was changed to that of an S engine however the choke is a little small. Would that affect the top end, should I consider making changes. Thanks.

Main Jet 1.30
Choke 30
Air Corrector Jet 1.85
Emulsion Tube F2
Idle Jet .45

[1QuickS]

The 30mm venturis will move the torque range down a little and improve signal to the main circuit, a little better for all-around driving without significant top end loss. I'd recommend 55 idle jets and F3 emulsion tubes which should make a decent package with what you already have.

Since your situation is not typical then you will need to drive it to determine how she goes and make adjustments accordingly. My web site has some good info regarding installation/maintenance/tuning: Performance Oriented

The IDTP Webers have a progression circuit designed for a rather lazy 2.0 (1969 911T and 914/6 engines) using 27mm venturis. You might suffer a transition lean spot and if you do then there are a few things that can be done to sort the issue without breaking the bank. The 30mm main venturis might be small enough to make the transition issue less obnoxious than experienced with larger venturis.

I do have IDS Webers available for sale if you like; please contact me via my web site email for more info regarding those. I also have F3s and 55 idle jets. Another item about the IDTPs is they use a stepped tip idle mixture screw which is finicky for idle mixture adjustments...I have replacements for those as well, they are machined of steel and are exact reproductions of the OEM mixture screws including the knurling pattern.

Cheers,

Paul Abbott

[Norm01]

Paul, I am trying to adjust these carbs, I removed all the Jets and mixture screws and cleaned them and decided to follow your instructions on your site and set the air corrections screws all seated and the idle mixture out 1-3/4 turns. First I am having a hell of a time getting the engine warmed up to even use the sync meter, the engine is spitting out of pretty much all the carbs. I turned out the idle mixture to 2-1/2 and it's still spitting, my idle screws are in about 3 turns rather than 3/4 just to try and keep an idle. I was under the impression that the idle air corrections stay in and you only turn them out to adjust to the highest flowing carb. Does it make sense I am compensating so much with the throttle plate or should I turn out the air correction screws to start. Thanks.

[Norm01]

BTW, the valves, timing and dwell have all been checked and are within spec. I will check the float bowl height later in the week when I receive the gauge I ordered. Need some help on where to start with the adjustments to keep it running.

[1QuickS]

Were the IDTPs installed and running on the engine or were they part of a package deal? The IDTPs should idle just fine assuming fuel delivery to the idle jets is clear. I provided a link in my posting of 19March (Post #2) to my site where basic setup info is offered. However:

• throttle stop screws 3/4 turn open after just contacting the throttle lever arm
• idle air correction screws closed (tho ones with the lock nuts)
• mixture screws 3/4 turns open (IDTP screws have a stepped tip which decreases their ease of fine tuning adjustment)
• float levels adjusted statically using fuel pressure (will require re-adjustment once engine is running)
• throttle drop links adjusted so they just snap into place (these will be re-adjusted once engine is running and disconnected during idle adjustments)

Spitting up through intakes is lean indication, if you have spitting while trying to get the engine to stabilize then you can determine which cylinder(s) are lean and open mixture screw for that cylinder 1/2 turn or more.

Be sure your idle jets are clean (look up at the sky to see through the tip) and it would be good to check for blocked hidden fuel gallery issues using the procedure on this web page: Performance Oriented