Distributor gear

inaminit · 03-16-2022, 05:40 AM

Helping a friend with a 77 turbo engine. Originally a crank fire ignition. We want to put a 79 dizzy from a 3.0 in, but it will not engage the brass gear. Dizzy is a 0 237 301 001. Do we have the wrong dizzy? We were told it was ok to use it in place of the unobtainable turbo unit. If it is wrong, what is the best solution? Thanks in advance.

boyt911sc · boyt911sc's Garage

The SC ignition distributors turn counterclockwise unlike most 911 distributors. I am not familiar with the 930 motors and would assume they have clockwise ignition rotation. If that is the case, for an SC ignition distributor to work it would need a different drive gear to match the gear at the crankshaft.

Did you inspect the orientation of the drive gear at the crankshaft? Looking through the Dizzy mounting hole, you could inspect if the drive gear is CW or CCW.

Tony

Flat6pac · 03-16-2022, 04:12 PM

The 3.0 turbo distributor runs clockwise
Bruce

john walker's workshop · 03-17-2022, 05:06 PM

Can't run a distributor in the opposite direction because the advance weights won't move outward, so pinion gear swap isn't going to work.

gled49 · 03-19-2022, 06:41 AM

FYI, on all of my CW Distributor engine rebuilds, I up grade to 3.2 brass crankshaft gear and distributor pinion. The dimensions are different and must be used as a pair, be careful campers.

Trackrash · Trackrash's Garage

Quote:

Originally Posted by gled49

FYI, on all of my CW Distributor engine rebuilds, I up grade to 3.2 brass crankshaft gear and distributor pinion. The dimensions are different and must be used as a pair, be careful campers.

I can't take credit for this, thanks to the poster.

gled49 · 03-19-2022, 12:52 PM

Yes for CCW distributors engines.

al lkosmal · 03-20-2022, 03:35 PM

There is a spiral groove cut into the distributor shaft. This groove (Archimedes' screw) is cut so that oil is directed away from traveling up the distributor shaft. If you rotate the clockwise distributor in the counter-clockwise direction and vice-versa........the spiral rotates the wrong way and basically forces oil up the shaft, into the distributor.

Ask me how I know.......

regards,
alft

mikedsilva · 03-21-2022, 02:40 AM

Quote:

Originally Posted by gled49

FYI, on all of my CW Distributor engine rebuilds, I up grade to 3.2 brass crankshaft gear and distributor pinion. The dimensions are different and must be used as a pair, be careful campers.

Just seeking a little clarification: So the SC runs CW where all the others run CCW.
So you are saying then when you build an engine that uses a CW dist, ie SC engine, that you change the drive gear on the crank, and the pinion gear on the Dist, to a 3.2 spec (ie, CCW).

When you say above that dimensions are different and they must be used as a pair, are you saying that you must use a matching pair of drive gear and pinion? Are they matched in the same way that transmission gears come in a matched set?

Thanks in advance, Mike.

OSC911 · 03-21-2022, 03:25 AM

Quote:

Originally Posted by mikedsilva

Just seeking a little clarification: So the SC runs CW where all the others run CCW.
So you are saying then when you build an engine that uses a CW dist, ie SC engine, that you change the drive gear on the crank, and the pinion gear on the Dist, to a 3.2 spec (ie, CCW).

When you say above that dimensions are different and they must be used as a pair, are you saying that you must use a matching pair of drive gear and pinion? Are they matched in the same way that transmission gears come in a matched set?

Thanks in advance, Mike.

No, I the SC 3.0 runs CCW, the 3.0 Carrera with six bolt flywheel runs CW as do the 3.0 turbos. As far as I know the 3.2 runs CW also.

mikedsilva · 03-21-2022, 03:32 AM

Quote:

Originally Posted by OSC911

No, I the SC 3.0 runs CCW, the 3.0 Carrera with six bolt flywheel runs CW as do the 3.0 turbos. As far as I know the 3.2 runs CW also.

sorry, I got them back to front... long day and fuzzy head.

I was more interested in knowing if the pinion and drive gears are a matched set....

gled49 · 03-21-2022, 07:44 AM

If you run CW distributor you must pair brass gear and distributor pinion. Early 901 parts or 3.2 parts. Don’t mix them. CCW SC parts are only critical if your engine # is early, (check # above in service bulletin). We once tested a late SC distributor in an early SC engine while troubleshooting a performance problem, and the distributor stripped the brass gear right off the crank, broke it in 1/2, had to split the case and overhaul the engine to replace missing brass gear. Be careful out there campers.