Jetting 40IDA's for 2.7

[drola]

i am putting a set of ida's on a fresh 2.7
what is a good base for jetting? what jets/emulsion tubes should i be using before i go crazy trying to adjust the carbs?

[1QuickS]

Cams? Compression? Daily driver or hot rod, high RPM application (time-trial)?

Main venturis are first item to be selected and are based upon application & engine details. You can get excellent main circuit performance with either F26 or F3 emulsion tubes but jetting will differ depending upon which type you have.

Also, be sure your Webers are IDA or IDAP, if they are IDTP then you will have a transition issue that will be troubling. I have a modification kit to help tune that issue away without expensive modification of the progression circuit.

[drola]

sorry i should have clarified.
motor is a freshly rebuilt stock 2.7. car will mainly be used for street driving with an occasional track day. i'm pretty sure they are plain ida's
i'll take a look today and report back with the current set up to see if they need to be changed. they came from a 2.0 so i'm assuming they need rejetting
carbs have never been my strong point so i'm trying to get this right

[1QuickS]

This would be a good combination to use for 2.7 CIS rebuild for street use assuming IDA or IDAP Webers:

• 32mm main venturis
• 135 main jets
• F3 emulsion tubes
• 170 air correction jets
• 55 idle jets

If you have F26 emulsion tubes then use 140 main jets.

Cheers,

Paul Abbott

[JOHN21BLACK]

Sorry to highjack, but 1QuickS what would be a good combination with 40TIN Zenith Tall intake manifolds on fresh 2.7 with J&E 9.5:1, 964 cam grind, port and polish heads, intake 40mm, light flywheel and pressure plate. SSI Headers 7:31 gear. thx

[1QuickS]

I'd contact Alan in the UK for that setup since he knows better regarding Zeniths and can supply modified venturis & etc. for them. Search this forum for "Alan.UK" to acquire his contact info.

Also, see thread by VFR750 regarding Zeniths installation on his 3.0SC:

http://forums.pelicanparts.com/porsche-911-technical-forum/738223-zenith-tin-2013-modifications.html

and

http://forums.pelicanparts.com/porsche-911-technical-forum/810574-zenith-ida-conversion-performance-oriented.html

[drola]

So here is what i found when i took my carbs apart:
30mm main venturis
125 main jets
F2 emulsion tubes
180 air correction
55 idle jets

[Evans, Marv]

I would listen to Paul Abbot. Below are some recommendations from a few different people.

Weber 2.7L Jetting Recommendations:
Name Cams Air Venturis Idle Jets Main Jets Emulsion
Bruce Anderson Solex 145 34mm 60 - 65 135 F3
Jerry Woods E (2.8L) 180 34mm 70 165 – 170 F3
Kevin Redman E 180 34mm 60 145 F3

[1QuickS]

Yes, those cams (E & Solex) are a bit more aggressive than CIS cams which is why I recommended the 32mm venturis. 34s would be my recommendation otherwise.

Although, many combinations can be made to work. I do not have a recommendation for F2 emulsion tubes. Comparing them by physical attributes the F2s are a bit leaner in the 4000 to 4500 RPM region than F3s and they would be a little later in their effectiveness; as in slower to initiate main circuit operation. Otherwise they are close to F3s; try'em & see if they work.

[drola]

Paul, do you sell these parts?
I would need everything but the idle jets.

[1QuickS]

I do. Please contact me via my email address:

info@PerformanceOriented.com

Thank you!

[drola]

Originally Posted by 1QuickS

I do. Please contact me via my email address:

info@PerformanceOriented.com

Thank you!

Email sent

[chris_seven]

We have been refurbishing and modifying 40TIN carbs for a few years now and have fitted them to a number of different engines from modified 2.2S right though to 3.0 litre engines producing around 260 BHP.

We have a range of venturis, pump jets, emulsion tubes as well as mains, idles and air correctors.

We modify the idle air correctors if required and also make gaskets and thermal insulators.

The venturis we supply have the 'choke' at the correct height and the shape of the converging side of the venturi has an exponential form to optimise air flow.

[crummasel]

Hi Chris,
could you please explain what parts you have for the TINs in terms of emulsion tubes (variants, usage etc..).

Also what parts in general

Thanks and greets,
Robert.