Rev-limiting rotor

[GaryR]

Anyone know what the specs are for these rotors? I see nothing available for any 911 from 78-83 except the turbo RL rotor - (Part # 930-602-901-01-M14, Pelican Parts - Product Information: 930-602-901-01-M14 ). I think the SC's have something up in the dash that acted as a cutout but not sure if that works or not so if I can toss the turbo part on that will work. Also like to know what the rev limit is on these rotors,,

Thanks

[Grady Clay]

Gary,

Yes, the 911SC has a rev-sensing box (J35 “Speed Switch”) that cuts off the fuel pump.
No rev-limiting rotor.

Has anyone made this adjustable?

Best,
Grady

[GaryR]

Thanks Grady - Will the turbo rotor fit/work in the SC distributor? Do you know what the RPM cut-out is for the "J35" and the RL rotor?

[SpeedracerIndy]

Euro SC do not have a rev limiting switch in the dash. I use the turbo rotor for my euro sc. It's a 7200 rpm cutoff. The cutoff is printed on the rotor.

[GaryR]

Originally Posted by SpeedracerIndy

Euro SC do not have a rev limiting switch in the dash. I use the turbo rotor for my euro sc. It's a 7200 rpm cutoff. The cutoff is printed on the rotor.

Thanks, i'll pick up a Turbo rotor, assume our dizzys are identical..

[Joe Bob]

My euro had that rotor and I used a turbo one.....there are different rev limits. They are inscribed on the rotor.

[GaryR]

Anyone get one from here? I see no choice in rev limit..

[Dan J]

I have the rotors in stock Your car should still have the rev limiter box in it

[GaryR]

Originally Posted by Dan J

I have the rotors in stock Your car should still have the rev limiter box in it

Thanks Dan, servicing her now, switching seats around, fixin a couple little things then I think she will come in to run a quick alignment/balance on her if you have time..

[FrankyV]

Since the euro and turbo rev limit is higher than the US spec SC, you may not want to go the rev limiting rotor route as PCA is planning to check rev limits more than in the past.

[GaryR]

Originally Posted by SkankyFrank

Since the euro and turbo rev limit is higher than the US spec SC, you may not want to go the rev limiting rotor route as PCA is planning to check rev limits more than in the past.

I believe that "J35 Speed Switch"is NLA so there is no choice in the matter AFAIK, but in the end I leave it up to my shop to make right and meet the rules.

[FrankyV]

Originally Posted by GaryR

I believe that "J35 Speed Switch"is NLA so there is no choice in the matter AFAIK, but in the end I leave it up to my shop to make right and meet the rules.

I am going to disconnect my functioning J35 and replace it with the turbo rotor since I have converted to Euro spec, let me know if you need it and I will bring it to the Glen.

[Dodge Man]

Turbo rotor (BOSCH 1-234-332-223)is 7000 RPM and about 1/2 the price of the Euro (BOSCH 1-234-332-240) is 6800 RPM. I have used them for years on an early 3.0 conversion. Not perfect but functional. The factory cut off fuel to save the TE or CAT from clogging with raw fuel.

[Grady Clay]

Has someone looked into the rev-sensing box (J35 “Speed Switch”) and documented the circuit?
If someone has the circuit diagram, it should be easy to have the rpm cut-off adjustable.

Does someone have a defective one I can have? I'll produce a diagram.

Best,
Grady

[GaryR]

Originally Posted by SkankyFrank

I am going to disconnect my functioning J35 and replace it with the turbo rotor since I have converted to Euro spec, let me know if you need it and I will bring it to the Glen.

Frank - Not sure what Dan J. is going to do but if you would bring it along that would be great and if i'm set maybe someone else may need it.

It sounds like the Turbo rotor (one guy said 7200, one said 7000 RPM) may not be legal for you if their is a special (2x the $!) 6800 RPM Euro rotor available..

Grady - depending on what my shop does you are welcome to mine as it was cutting me out at anywhere from 5500-6000 and is NG as-is..

[FrankyV]

Originally Posted by Dodge Man

Turbo rotor is 7000 RPM and about 1/2 the price of the Euro 6800 RPM. I have used them for years on an early 3.0 conversion.

I was under the impression that the Euro rotor is NLA, where can i find one? Since the rev limit specs have a tolerance of +- 200 rpm, the turbo rotor could work for a Euro SC and be club race legal but you never know. Does yours cut in at 7k or below?

[FrankyV]

Originally Posted by GaryR

Frank - Not sure what Dan J. is going to do but if you would bring it along that would be great and if i'm set maybe someone else may need it.

It sounds like the Turbo rotor (one guy said 7200, one said 7000 RPM) may not be legal for you if their is a special (2x the $!) 6800 RPM Euro rotor available..

Grady - depending on what my shop does you are welcome to mine as it was cutting me out at anywhere from 5500-6000 and is NG as-is..

I will have it with me. Oh yeah, mine is cutting me out at 4000, that is why I am so slow For real though, it actually cuts in at the top of the tolerance range, perfect for a D car, I haven't switched it out yet because we wanted to keep the revs down a bit during engine break in.

[Grady Clay]

Gary, you have email.

Guys,
There are ± trade-offs between the SC fuel pump cut-off rev limiting and the rotor type.

The electronic cut-off is probably better for track use where you regularly approach (but never touch) the rev limit.
The fuel pump cut-off never comes into play unless you err by revving a bit more.

With the rotor type, the engine begins to misfire as it approaches the limit.
This can be as much as 500+ rpm below the stated limit.
Testing on an engine dyno, I can detect the misfire sometimes as far as 1000 rpm lower than specified.
On dyno runs, I always installed a non-rev-limit rotor.

For street use, the rotor type gives a ‘softer’ limit to the revs as you can feel it over the preceding 500 rpm or so.
The electronic fuel pump shut-off is very sudden and abrupt, causing the engine to off/on/off/on rapidly.

Best,
Grady

[GaryR]

Got it Grady, let's see if Dan can get mine working. If not it's yours else if he does maybe Frank will donate his!

[Dodge Man]

Originally Posted by SkankyFrank

I was under the impression that the Euro rotor is NLA, where can i find one? Since the rev limit specs have a tolerance of +- 200 rpm, the turbo rotor could work for a Euro SC and be club race legal but you never know. Does yours cut in at 7k or below?

I passed on the Euro rotor for the Turbo about a year ago because of the $$. I believe that Pelican actually had them and I found them with a search. I still have the old 6800 out of my ROW 3.0 that was working fine (stored in the glove box for that middle of nowhere failure monent).

PELICAN: OEM-93060290102 (1 234 332 240) Genuine Porsche Part: DISTRIBUTOR ROTOR- This is a special-order, non-returnable, Porsche part
(availability and shipping charges may vary). $51.00

EURO REFERENCE: Rotor, distributor Porsche 911 from Bosch - 1 234 332 240