Location of 3mm enrichment screw on early CIS

[ARCSinAK]

Can anyone help me out with the location of the enrichment screw on a early CIS system 74. It's different from my 80SC which has a cap/rod to locate the screw. Tried holding a camera above fuel distributor no luck.

Thanks.

[Peter Zimmermann]

'74 is in the same place as the '80 car. Maybe the '74 has a plug of some kind in the wrench access hole? Maybe the rubber dome is deformed enough to partially block the hole?

I don't understand what you mean by "cap/rod to locate..." on your '80 car...are you talking about the plug to keep dirt out of the hole?

[ARCSinAK]

Hi Pete yes I was talking plug on wire with a loop on my 80SC which covers the hole to the air flow/enrichment screw. I used the 80sc location for a reference and found the hole but the screw to adjust is frozen. Tried blowing out with air using a pick to remove debris and letting Koil oil run down the pick to free the frozen screw, no luck. My car hunts at idle and randomly cuts out over 4 G on acceleration. When I push down on the screw it smooths out at idle. I wanted to richen the mixture. Anyone have thoughts on why, especially when up to engine temp or hotter on my 2.7 230 degrees it cuts out/bogs. I find that when it below 180 degrees she pulls nicely up to 6K. Seems like a fuel issue, the car has a new Bosch fuel pump and runs well otherwise.


Thanks for your thoughts.

[Flat6pac]

spray some good lube down the hole. The 3 mil allen set is small but the threaded screw is quite large.
Bruce, so spray plenty.
Bruce

[ARCSinAK]

Thanks Flat Six I will try I was a bit worried about adding lube to that location. I was able to put torque on the screw but the force was great and I did'nt want to strip it. Do you think this mixture adjustment could help the problems with the engine cutting out over 4K ?

[ARCSinAK]

Took off the air cleaner and was able to push up on the air flow sensor I believe and gain better access to the allen key from the top by the fuel distributor. She doesn't want to turn at all, do I dare use a vise grip and go for it. Could be 40 years of corrosion on the screw but I don't want to be a goon and break something.......

[Ronnie's.930]

Yes, an overly rich condition can cause the engine to misfire under high load. I've recently had this problem with my car, a 1987 930 with K-Jetronic/CIS.

[ARCSinAK]

Don't think I am too rich, here a plug photo. Seems like I dont have enough fuel on fuel acceleration over 4K strange part is it's random and happen most of the time when the engine is at or above operating temp. Have yet to have the balls or lack of brains to force the screw to turn, afraid of stripping out the 3mm allen head.

[timmy2]

What is your regulated fuel pressure when you are running hot?
Maybe the WUR (system pressure regulator) is out of whack...

[Peter Zimmermann]

Just wondering, do you still have ignition points in your distributor? If yes, have you set the dwell (38 +/- 3 degrees) & ignition timing? If your car runs that hot the dwell/timing might be off just enough to cause a problem. BTW; plug color looks good, gap correct?

Check this while the screw is soaking. To free it up might require sensor plate housing removal and working with it on the bench. This will also allow you to verify sensor plate height while the unit is open.

[Ronnie's.930]

I guess I came to the conclusion that you were running rich based upon your comment that the idle was hunting which is almost always the result of a rich condition with K-Jet (albeit at idle). The plug in the picture looks good, however.

[ARCSinAK]

Not sure how to test my regulated fuel pressure. I am running points PO removed CDI. Going to have to check the Dwell/Timing. Can that alone cause a 2.7 to run hotter? I plan to add a front cooler soon, I have the oil lines from a SC and a trombone just need a external thermostat.

[Jim Williams]

Originally Posted by ARCSinAK

Not sure how to test my regulated fuel pressure. I am running points PO removed CDI. Going to have to check the Dwell/Timing. Can that alone cause a 2.7 to run hotter? I plan to add a front cooler soon, I have the oil lines from a SC and a trombone just need a external thermostat.

Check here.

911 CIS Primer - Testing: Pressures

[Millweigh]

Arc,

You will be best served if you do determine your fuel pressure measurements
for system and WUR cold and hot test conditions per the previous threads.

See Link for backup info on 77 911S fuel flow problem:

http://forums.pelicanparts.com/uploads23/WUR_Refurb_Cal.pdf

I won't overwhelm you with the 50 plus thread I just worked with the guys here,
but did have an engine malfunction at 3100RPM due to a lack of pressure that the
WUR was not providing to the Fuel Distributor (FD). The differential pressure in the
FD is important to allow the proper fuel flows to occur at higher engine speeds.

The gurus will chime in as you gather your information, believe me, you will get it
resolved, but you will need to listen to their "Go Do's" carefully.

Best of luck, Paul

[ARCSinAK]

Thanks for all the help!