Size of allen wrench for CIS Fuel Adjustment??

[VaSteve]

I think I'm trying to adjust the wrong screw when attmepting to adjust my CIS fuel mix.

I have seen a number of posts where the allen wrench should be a 3mm. Using Wayne's book, and following the photo, I found a hole next to the boot and the F/D that's 5.5 mm. Am I trying to adjust the wrong screw? It's a really tight fit for my tools/hands so I'm thinking I have the wrong one. Is they one actually behind this hole? (Any got a photo handy?)

Also, how much can the idle screw turn before noticing it on the tach?

This wouldn't be the first time I goofed something up.

Many thanks all!

[yelcab1]

3 mm allen wrench, very long one. It takes 1/8 of a turn to get 1.5-2% change in CO mix.

[VaSteve]

The hole I was trying to adjust was right next to the boot, I must have wrong one. Can you see this hole without a mirror while looking at the engine?

[Bill Verburg]

This is the factory tool, 3mm

[john70t]

Should be 3mm, same as VW CIS. I wonder if the distributor units/lines/injectors/WUR are compatible as well.

[VaSteve]

Ok. I'm going to give it a crack again tommorow, once it's done raining. Does anyone know how much I can turn the idle adjustment screw before I will see a change? I turned about 1/8 and didn't see any change. Admittedly, my mix is kind messed up (rich)

Thanks

[Paulporsche]

You should only turn the screw a max of 1/16 turn each time.

The hole is on top of the mixture control unit, to the right of the boot. To lean, turn counterclockwise, as viewed from the top.

Leaning typically raises the idle, and richening decreases it.

Do you have an airbox popoff valve? Is it seated, sealed, and located correctly?

On my car, a too rich mixture causes a fluctuating idle speed, while too lean causes the popoff valve to pop open. The correct mixture produces an almost black, very dark brown color to the inside of the tailpipe, and the engine revs freely to the redline.

If you have a gas analyzer, you should be somewhere 3.5% CO according to JW, although each car will vary somewhat.

I also find I have to redajust my mixture slightly richer by 1/16-1/8 turn each fall, and lean by the same amount in mid spring, although my temp range here in Toronto would be more drastic than yours in VA.

If this is your first time, make sure you are engaging the grub screw down inside under the hole.

Good luck.

Paul

[Sunroof]

Hey Steve..
Somethings to keep in mind.

When I first tried to adjust my mixture the hex wrench would just turn freely. Weird?! Well it turned out that the previous owner dumped a bunch of locktite down there and covered the hex adjustment screw. I wound up using picks to get it all cleaned out, but it was a very unusual circumstance.

A good thing to keep in mind.....

right - rich (clockwise)
left - lean (counter clockwise)

Just one small click at a time. Its sensitive.

If you have trouble turning it....with the engine off, take off the air filter cover, and reach in and hold the sensor plate with one hand firmly, while you adjust with the other.

Bob
73.5T/CIS

[Paulporsche]

Take the allen key out after each adjustment and rev the engine. Then drive the car, or test w/ analyzer.

Once i had debris fall into the hole and clog the screw. A thin wire should clean it out, or I had good luck dropping a little WD40 down the adjustring key shaft into the screw head, then cleaning it out before adjusting.

Paul

[VaSteve]

OK, I will give this a try tommorow. Assuming I get the mix sorted out, how much does the idle screw (on other other side by the heater fan) turn before noticing adjustment?

Thanks!

[Paulporsche]

Just a wild approximation: 1/8 turn should give you something like 100 RPM. As far as I know, you cannot cause any engine problems from over rotating as with the mixture unit, since it just allows more or less air to bypass the idle adjuster, so if it is not enough or is too much, just give it more.

Paul

[GB83SC]

Steve, do not adjust anything in the motor-bay without dropping the motor first, that's the law in NoVA

Try to find someone who has analyzer for best results.

My freind Jon Estrella in Leesburg has one.

[vash]

hey, i dont know much about this because i just bought my lambda car. an 81 SC. i know there is a trick of the trade of using a dwell meter set on the 4 cylinder setting where you can read your mixture. you hook the dwell meter to the lambda signal duty cycle test connector. start car and warm it up. and turn the 3mm allen until the dwell meter reads 45deg. you will nail your CO mixture. but there is a disclaimer that all other ignition and injection parts must be in good working order. i guess instead of sticking a sniffer into the exhaust pipe, you use the lambda sensor as the sniffer. genious. i will locate the duty cycle test connector tomorrow at a PCA tech session on tuneups.

cliff
p.s. a 5.5 mm allen fits perfectly through the hole but will not seat within the 3mm allen head. that is why you are turning and not getting any change. you bigger tool is just riding along the top of the allen. you will feel clicking or "indexing" when you get the right tool during the turning.

[Paulporsche]

Neither my 77 nor my 80 engine mixture adjustments would produce "clicks". You would have to guess the amount of rotation by feel. Does anyone know which years click?

Paul

[VaSteve]

Originally posted by vash


cliff
p.s. a 5.5 mm allen fits perfectly through the hole but will not seat within the 3mm allen head. that is why you are turning and not getting any change. you bigger tool is just riding along the top of the allen. you will feel clicking or "indexing" when you get the right tool during the turning.

That must be my problem. I'm off to give it a whirl!


George, I'm just hoping to get it going enough to make it to Porsches Under the Stars tonight. We can drop the engine tommorow. (Or I'll talk to Jon about the gas analyser!)

[RoninLB]

my old stock CIS ran better at 3.5 with the dizzy vac permanently disconnected.

[VaSteve]

Thanks, all. I see what I was doing wrong. I didn't realize the wrench had to drop into the hole a ways. Could they have made this more difficult to reach?