Dwell meter timing light suggestions

[gliderguy]

Hello Everyone! Newbie here, looking for suggestions on a

decent timing light and Dwell meter to help me with my 76.

Mechanically inclined, lacking Porsche wisdom, but learning a little

more every thread!

[rattlsnak]

Not sure why you need a dwell meter, but either a snap-on or sears light with the adjustable advance works fine.

Its not worth getting one without the advance feature. Snapon is quite $$$ though. the second one has a tach/dwell feature as well.

http://buy1.snapon.com/products/diagnostics/time_mt1241P.asp?tool=diagnostics&Item_id=10988&PartNo=MT1241P&Price=383&Desc=&SUB_Cat_ID=125864&SUB_Cat_NAME=Timing+Lights&Cat_ID=125627&Cat_NAME=Diagnostic&group_id=1388&group_NAME=Timing+Lights&store=snapon-store&dir=catalog&pix=objects%2F19700%2F19695.JPG&email=true

http://buy1.snapon.com/products/diagnostics/time_mt2661ap.asp?tool=diagnostics&Item_id=10985&PartNo=MT2261AP&Price=516.28&Desc=&SUB_Cat_ID=125864&SUB_Cat_NAME=Timing+Lights&Cat_ID=125627&Cat_NAME=Diagnostic&group_id=1388&group_NAME=Timing+Lights&store=snapon-store&dir=catalog&pix=objects%2F44600%2F44559.JPG&email=true

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00921023000

[gliderguy]

maybe I am using the wrong term for dwell. Allows you to check air fuel mixture?

[Rex Walter]

Gliderguy,

I have the Sears model that Rattlesnak shows, and it works very well for me. I could not live without the dial in feature. If you are still running points, a dwell meter is a good idea. I have, in an emergency, set points using a match cover for thickness, and been spot on when I finally got near my tools. But a dwell meter beats any feeler gauge in my book.

Rex

[Early_S_Man]

I have an older version of the Sears Craftsman at the bottom of Chris' list [a relabeled KAL 4185/Actron CP7519] ... ands it works great for under $100! A PDF-file copy of the user manual is at the link below:

http://www.actron.com/publish/2004/06/07/pdf_english_16182.pdf

Actron CP7519 details:

http://www.actron.com/product_detail.php?pid=16182

The SunPro/Actron CP7676 Automotive Digital Multimeter includes tach/dwell functions ... works well, and is featured in the Bentley manuals for SC and Carrera.

http://www.actron.com/product_detail.php?pid=16291

User manual is here:

http://www.actron.com/publish/2005/03/28/pdf_english_16291.pdf

[Rex Walter]

Gliderguy,

A dwell meter will show how long points are open, and thereby the point gap.

Rex

[gliderguy]

Thanks for the input! What will tell me if my air fuel mix is correct?

[fireant911]

gliderguy,
You are referring to the duty cycle though I do not know if this will work on your car. The three-pin test connector is used, at least on mine, when performing the A/F adjustment with this methodology.

[fireant911]

Originally posted by Bob Tindel in the 911 Q&A section
How do I set the mixture properly on my 911 CIS motor?
The procedure is to use a high-impedance (digital) dwell meter to measure the duty cycle of the CIS frequency valve. You can do this from the test connection inside the electrical panel at the left rear driver’s side of the engine compartment. It’s the little black plug with a cap, near the CD box. Inside are three connector pins. Connect the positive lead of the dwell meter to the green/white wire pin, and the ground to the brown wire pin. When the engine is at normal operating temperature, the reading on the dwell meter should dither around 45 degrees (using the 4-cylinder scale), typically ranging from 40 to 50 degrees. This translates to 50 percent duty cycle, meaning that the frequency valve is on half the time, and that your basic mixture setting is good. (If you are lucky enough to have a meter that measure duty cycle, obviously you are looking for about 50 percent.)

If you see a higher dwell reading, say 70 percent, it means that the system is trying to control a basic mixture setting that is too lean. Conversely, if you see a low reading, say 30 percent, it means that the basic setting is too rich.

The mixture is adjusted using a special 3mm Allen wrench, through the hole between the fuel distributor and the rubber air duct. Turning this screw to the right makes the mixture richer, left makes it leaner. Never blip the throttle while the wrench is in the hole, or you may bend the air sensor plate. Also, you want to finish the adjustment by turning to the right.

All of the above assumes that you are working on a 80-83SC, with the Lambda oxygen sensor. Correct basic mixture setting helps smooth transition from cold start to warm running, and overall efficient operation.

[Early_S_Man]

gliderguy,

If your '76 is stock CIS ... it doesn't have a frequency valve or O2 sensor! That means you don't need to worry about duty cylce or adjustments to the O2 system, an add-on system to SC engines.

Your mixture is adjusted with a 3 mm hex key while monitoring the CO output with an exhaust gas analyzer such as the Gunson.

[gliderguy]

correct no O2 sensor I have the 3mm allen, and contemplating a Gunson. Would to rich a mix possibly cause it not to start?

"After the passing of many moons maybe I will be able to answer some tech questions, right now just a empty spounge soaking it all in!!!"

[Paulporsche]

I suppose it's possible, but usually a too lean mixture would be more likely to do it. You should do a search. There is a huge amount of info on CIS starting issues, including air leaks, WUR, AAR, AAV, CSV,check valve, fuel accumulator problems and on and on...

[stlrj]

Dirty points will cause a no start. So will points not opening or closing.

Joe