CIS rich to lean adjustment - 1977 2.7L

[kach22i]

Per the "101 Projects for your Porsche 911" book I have located the fuel mixture adjustment allen wrench hole (page 96) located between the fuel distributor and the large rubber boot above the engine and behind the airbox.

When I started the adjustment with a 4.5 mm allen wrench I swore I had it rotating counterclockwise to lean it out. I'm not so sure about the "clicks" I was supposed to feel.

I think I made a small improvement and leaned it out. The little fart-like mini backfires I was getting when I lifted off the gas seem to be minimized but they are still present.

Reference link - see "UPDATE":
http://forums.pelicanparts.com/showthread.php?threadid=184348&perpage=20&highlight=walker&pagenumber=2

Upon closer inspection and based on feel it looks like the allen hole is not a female allen but a stripped out screw hole. I just can't get any grip and feel rotation. I see no rotation using a flashlight.

To get a better grip I tried to use a slightly larger and longer allen wrench (non-metric) but it would not fit as the 5mm would not fit (too large) either.

I tried to get the 4.5mm allen wrench down in the hole deep with the engine running, but it seemed to slip down in the hole and the engine wanted to stall.

What the heck is going on?

The only allen wrench in my factory tool bag/pouch is very large.

I'm not sure what to do, please comment, I'll try to post a photo soon.

[Scott R]

WOW, a 4.5 should not fit at all, this is a very exacting fit with a 3MM. Is it possible you have some junk like old engine sound pad in the adjutment hole? Also if you remove the airbox cover and rotate the screw you can see the arm moving if you have it.

[kach22i]

I was thinking that maybe something slipped though, is this the best picture of the system?

http://members.rennlist.com/jimwms/CIS/CIShome.html

[sammyg2]

3mm. you will be able to feel it engage.

[kach22i]

Two theories at what is wrong with my situation.

1. I was using short, not long allen wrenches. This means I was in the hole but not going down to the butterfly/plate which comtrols "richness & leaness". When I felt the wrench drop in the hole and press on the plate below it wanted to stall the engine.

2. The screw is missing! I should not have a "hole", I should have a "SCREW " to adjust - Wayne's book says the "SCREW" is indexed to click, nothing about an access hole, or a hole leading to another chamber. The screw is missing! All I'm left with is an freak'n hole. The clearly threaded hole size is just a hair over 4.5mm.

Conclusion:
There is a missing indexed adjustment screw with an outside thread of about 5mm. This indexed screw has a 3mm female allen hex recess in the head or top of it's stem. The screw is designed to limit the upper range of the plate/butterfly action & motion by pressing down on the butteryfly/plate and not allowing it to spring all the way back up.

I took a very long and skinny SAE allen wrench (less than 3mm) into the hole, it then pressed down and I could see and hear the lever (butterfly plate) move.

I have no idea what happened to the screw or how long it's been missing. When I sprayed carb cleaner in that area yesterday there was no increase in idle speed - had fire extinguisher handy just in case.

If right about this, what is the Pelican order number or specification of the screw? Length, thread count etc....

[Oh Haha]

The "threaded hole" is where a plug would normally reside covering the 3mm screw.
I don' think the car would run without the adjusting screw. Could be wrong, though.
When I adjust mine, I don't "feel" the clicks but I only move it a small amount depending on the season. Richer for fall, leaner for summer.
it is still possible that the PO has stripped the 3mm opening for you.

[kach22i]

Originally posted by Oh Haha
The "threaded hole" is where a plug would normally reside covering the 3mm screw.
I don' think the car would run without the adjusting screw. Could be wrong, though.
When I adjust mine, I don't "feel" the clicks but I only move it a small amount depending on the season. Richer for fall, leaner for summer.
it is still possible that the PO has stripped the 3mm opening for you.

From what you wrote Wayne, sounds like I should not be able to poke anything straight through to the plate because there would be a screw plugging the hole. I can poke straight through, nothing but a vacant hole, no cap, no screw.

Some other clues now make sense to me. There was no CIS leak when I started, but I did not retest with carb cleaner after playing with the hole. I bet the results would be different now.

Clue one:
One of the lines nearest the rubber boot and the hole was some old blue silicone which easily rubbed off. My first thought was A-HA! Someone sealed up a CIS leak with blue silicone at some point in time. They have not made blue silicone in 20 years, first blue then came black silicone, then clear silicone in a tube. Anyway, it was not a line leak they were sealing but the hole left when the adjustment screw was ejected out from a large backfire - maybe they were replacing the airbox or something - just guessing. Maybe the screw fell in and was lost many years ago. It's not in the airbox now, that's all I know. Could it be rattling around somewhere?

This blue silicone was there - fact. I slowly removed it by rotating my allen wrench. The little plug of 20 year old silicone is in tiny pieces melting in my engine intake manifold somewhere I assume.

Let's assume the adjustment screw is gone, and some mechanic got it running by making adjustments elsewhere in the system. I still have a car running too darn rich and making little backfires when I let off the gas after high rpm's. I still need an adjustment screw.

Background:
I have no vaccum advance line runnning from the distributor air regulator to behind/below the rubber boot on top of the engine. Both ends are sealed. At somepoint in time some wrench was taking a lot of half-a$$ed shortcuts to get the car running. This may of even included the reason why I ended up having to reindex my distributor with the timing so off.

[Oh Haha]

Wow, this has been some adventure, George.
I am passing this issue on to the more experienced guys here. Apparently, it will run without the screw.
Could you use a small mirror and a flashlight to see down into the adjusting screw hole, just to verify that is indeed gone? Without it, I don't think you have a chance on getting it to run right. You might consider calling Monk's and ask Chris if he has a spare one on the shelf or could help in any way.

[kach22i]

Originally posted by Oh Haha
Wow, this has been some adventure, George.

Yea, fun and fustrating - always learning though.

A screw is a screw. It has a diameter, a thread type and count, and a length. I'm sure I'll get something to work.

I have the dizzy dead center and the timing right.

I have an idea of what my problem is now, and that's half the battle.

[Scott R]

If you have actually lost the screw and have other evidence of tampering I would remove the air flow sensor plate assembly and fuel distributor combo. Order a new keyway gasket and crush rings for the fuel hose connections on the injector lines, and the feed and return lines. It takes a few hours to get it out, however I don't see how could replace the screw otherwise.

[Paulporsche]

It's highly unlikely that the screw is missing. I think there is a stop built into it so that it can't be turned too far. Having said that, I realize that strange things do happen, especially to older, previously owned cars.

More likely is that the screw head is filled up with something. As someone else said, it is often crumbs from the foam sound pad.

It could simply be that you are not actually accessing the screw with the long skinny tool you mentioned and are alongside it and pushing down on the plate.

This happened to me years ago. I made up a new "tool" from a coathanger wire. I got it down into what I felt was the clogged screwhead. I then dribbled down some solvent down the wire into the screw. I waited and repeated. I then reamed the screw with the wire, cleaning out the accumulated gunk. The 3mm Allen tool then fit perfectly into the screw and the adjustment was made.

I then fashioned a plug out of a piece of brass tubing wrapped with self vulcanizing rubber tape at the bottom end to plug the hole.

If you have silicone in the screwhead, then the solvent probably won't do much, but reaming the screw with the wire should clean it out.

If that still doesn't do it, then you may have to disassemble it.

Good luck and report back.

[kach22i]

Originally posted by Paulporsche
It could simply be that you are not actually accessing the screw with the long skinny tool you mentioned and are alongside it and pushing down on the plate.

Is the adjustment screw attached to the plate then? If so I can still make the adjustment.

Is the access hole just a hole? If not, then I need a new screw.

Like I said, I do not have a properly long 3mm allen wrench at the time, but a slightly skinnier SAE can and does push down on the plate.

My access point/hole is a threaded hole which may of been clogged with blue silicone, junk and dirt.

[vash]

have you even tried to stick a 3mm allen in there? there is alot of vague-ness going on in there. the allen needs to be the long handle version, maybe 4-5 inches long. you will feel it engage. if you stuck the 4.5, i bet it would feel like you were turning something. it is probably rubbing against the sides of the holes, and fooling you. i have done this with even a 3mm. jabbed it in, thought i was changing things, even had the placebo effect with "yea, now it is running better" only to feel the allen drop into place correctly when i am trying to pull it out. duh.

the access hole is just a hole. on my car it is left open. as a matter of fact i have never seen a plug on any car. i guess those were easy to lose.

[kach22i]

Originally posted by vash
if you stuck the 4.5, i bet it would feel like you were turning something. it is probably rubbing against the sides of the holes, and fooling you.

That is what originally happened, ended up cleaning out the threaded hole.

The first tool I used was the short 3mm I have, and I most likely started making a hole in the silicone for the larger wrench to get it's feel for the threaded hole.

I hope this is not to hard to follow. It sure confused the heck out of me doing it.

[Paulporsche]

The hole is just that: an access point. The actual screw id down in there. You have to have the long tool as others have said. Make sure the tool is centered in the access hole and plumb (vertical). Once you find the screw head, you will know it. Often when I pull the tool out /I can even feel the plate raise up a little and then drop down into position.

BTW I've had 3 of these...one for my 78 Scirocco, one for my 77 911 and one for my 80 engine. None of them clicked during adjustment.

[kach22i]

Originally posted by Paulporsche
The hole is just that: an access point. The actual screw id down in there. You have to have the long tool as others have said. Make sure the tool is centered in the access hole and plumb (vertical). Once you find the screw head, you will know it. Often when I pull the tool out /I can even feel the plate raise up a little and then drop down into position.

Perfect, exactly the information I was looking for.

Now the next question, do I have to seal the hole when I am finished?

Anyone have some blue silicone?

[Paulporsche]

Make up a plug as I described. You don't NEED one for air metering. It's just to keep new crud out. Anything will do as long as
it fills the access hole, doesn't protrude down more than about 1/2" or so, and stays put until you need to remove it.

[vash]

a short allen can drop in there, but no way in hell you will have enuff to turn. get the long wrench and report back.

[ubiquity0]

Originally posted by kach22i

I'm not clear if this photo illustrates how you are trying to locate/engage the adjustment screw w/ a hex key, but the angle is way off.

You need to 'drop' a 3mm hex key vertically. The pic makes it look like you are trying to insert the hex key from the side, 30 degrees off vertical.

[Paulporsche]

You need a key about 4 or 4 1/2" long as was mentioned previously and get the key in the re straight. I mean plumb and centered in the access hole.