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-   -   1981 SC (ROW) Rev Limiter/CD Box Questions (http://forums.pelicanparts.com/porsche-911-technical-forum/492323-1981-sc-row-rev-limiter-cd-box-questions.html)

FL911 08-17-2009 05:29 AM

1981 SC (ROW) Rev Limiter/CD Box Questions
 

My engine has developed a miss (fuel or Ign.) at around 4000 rpms all of the sudden.
I have read up on 20 or so things that could cause this but I am still not sure and do not want to spend a ton of cash chasing this gremlin.
I am pretty sure it is a fuel issue because it pulls like a freight train in first gear then in second is when the hesitation starts.............like the fuel is being cut off.

Questions:
I read that ....... The USA SC's have a rev limiting relay up in the front, behind the oil pressure/temp gauge. It cuts power to the fuel pump.
Could this be my issue?
Another post I read..........stated that the SC's from 1980-83 had the rev limiter installed into the CD Box.
Another one .............rotor that is the rev limiter ...........(which mine does not have) but should it or not?
Another stated that .............the fuel pump relay could be bad.......is this located under the dash or in the engine compartment?


Any help would be much appreciated.SmileWavy

Thanks
Frank

Daviboy 08-17-2009 05:41 AM

Frank, Sounds like could be a fuel issue. Mine is an 82 ROW SC and I had the same problem until I took her to the local Bosch tech who sorted out my fuel pressures and adjusted my CIS now no more problems till I hit about 6200 rpm which I have been told is the max I will see. Which is fine as I can get 120 mph in 4th at that then slide her into 5th.....

arrivederci 08-17-2009 08:40 AM

ROW 81 SC should only have a rev limiter in the rotor. With a US rotor in a ROW SC, it'll rev till it blows up...not cut out prematurely. I just put a '78-'86 Turbo rotor in mine - extends the rev limit to about 7300. At the track this weekend I verified that it works.

ischmitz 08-17-2009 08:42 AM

The stock 6-pin Bosch CDI boxes do not have a rev limiter installed. The only box (to my knowledge) from Bosch with a rev limiter is the 935 8-pin CDI unit. And that is unobtainium.....

Your issue is either a fuel (mixture) issue or fuel delivery (fuel pump, filter, releay) related.

If it only happens under load and at 4000 RPM it could also be the advance mechanism in your distributor being balky. Have you check that?

Ingo

Flat6pac 08-17-2009 09:22 AM

I was always under the impression the limiter is built into the SC tach
Bruce

Daviboy 08-17-2009 11:04 AM

Ingo your right on the dizzy as well that was another of my problems. Cleaned mine up as per instructions from I think Gunter, and reset timing. Remember ROW cars shoud be set to 25deg BTDC at 4000 rpm with vacuum line disconnected.
See attached for more detail

http://forums.pelicanparts.com/uploa...1250535863.jpg

FL911 08-18-2009 04:31 AM

Thanks you all, I will get back with you after I check the fuel pump relay and the fuel pump.
I read Gunter's post on the "Distributor Service" and that is something I will do this weekend.


Sit tight and I will let you know how it goes.

Thanks again

Skitstoval 08-20-2009 06:40 PM

(BOSCH) Rotor Part Number - 1234332223
or 930.602.901.01 - Rotor, 930Turbo 76>79 3.0 & 3.3 7000Cutout

Skitstoval 08-20-2009 06:42 PM

Also physically check that your cable is plugged in snuggly to the CD Box


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