What jets are people running?

Timo · Post by **Timo** » Thu Sep 20, 2007 1:33 pm

OK just out of interest I was wondering what size jets/venturi's people are using in their 912's carbs's. Mine has twin weber 40 idf's fitted and I was just wondering if it is jetted correctly for peak performance. What jets/venturi's are other people running and what is performance like?

ar_kid · Post by **ar_kid** » Thu Sep 20, 2007 9:47 pm

What jets are people running?

L-jet

Type 4 style

Timo · Post by **Timo** » Fri Sep 21, 2007 1:33 pm

Thanks for that

Nige · Post by **Nige** » Fri Sep 21, 2007 1:55 pm

the only way is to get it setup on a rolling road, they'll all be abit different on what jet sizes they need. It doesn't have to be a Porsche specialist, but somebody use to setting up multiple carbs. I took my 912 to a local guy who races MGs, he fettled it on his rolling road, opened up the jets tweaked the timing and it ran the best it ever had done. All for £50!

Timo · Post by **Timo** » Fri Sep 21, 2007 4:16 pm

I was just trying to get an overview really of what different jets people were using and what power results different setups will give (ie more low down torque or top end power) Only reason I ask is because my webers are running 28mm vents with 52mm idle jets and 115 main jets and in the original guide book I have which refers to the solex setup it states 32mm vents with 55mm idle jets and 120 main jets. I am aware that I can take it to a rolling road and get them to play around with it as I have done this before with my previous car (they didn't actually manage to improve on the setup I already had) but from my experience the people who have experimented with there own cars setup in different ways and have gained good results is as good a way of doing it.

revival-cars · Post by **revival-cars** » Sun Sep 23, 2007 12:12 pm

Citations usually

Graham · Post by **Graham** » Sun Sep 23, 2007 8:37 pm

Try F7 emulsion tubes,130 mains,55 idles,and the air correction jet on top of the F7(Im guessing you have F11's) 170 I think.
And 32mm venturi's,28's are too small.

Timo · Post by **Timo** » Sun Sep 23, 2007 8:53 pm

Cheers v much Graham, looks like mine are way out then as I suspected. Yes its got f11 emulsion tubes and what look like 200 air correction jets.

Think I'll try and get hold of some bigger bits in that case.

Graham · Post by **Graham** » Mon Sep 24, 2007 8:58 pm

Looks like you have the older VW type webers,these also have a cam operated accelerator pump,where as later webers have a rod operated one,the cam ones can throw alot of fuel in,causing the car to run rough/rich on pick up,they are a pain to calibrate,I have in the past reprofiled the cams on them to lessen the "squirt"!,though again I think you can also replace the accelerator nozzles.
Doing all those bits should transform your car.
Good luck.

Timo · Post by **Timo** » Tue Sep 25, 2007 1:09 pm

I think they have the rod operated pump tbh, I bought them brand new a week ago from vw speedshop in manchester so I would think they should be the latest design. However when I bought them Paul did mention that they stocked 2 differently jetted versions of the 40's one sort with 28mm vents and one sort with 32mm. I thought I needed the ones with 28mm as this is what the old broken italian ones were running that I had removed from my car. It looks as though I should have chosen the 32mm ones with hindsight! However I spoke to Jim Calvert at stateside tuning last night and he recommends a very similar setup to what you have advised so I am now awaiting the arrival of some 32mm vents, 135 mains, and 180 idles, he reckons the 52mm idles and f11 emulsion tubes that I have should be fine with that setup so I will give it a go and let people know the result

cheers for all the advise