930 distributor dimension request

[b930]

Hi all, I don't have my 930 distributor installed or laying around since installing my EFI system and was in the need for a few reference dimensions. I'm running batch injection and wasted spark at the moment with a 60-2 crank wheel only and I want to go full sequential. I don't want to use the rear of the cam gear as I have got rid of all the emissions pump stuff and I have SC cams and I cant remember if they have the threaded holes for bolting up the smog pulley anyway.

I do have an old 2.0 / 2.2L marelli distributor that I want to make into a cam sync sensor. I note the shaft gear looks the same as the 930's, a 12 tooth gear with the helix in the right direction. The body shaft OD is too small and will need sleeving to bring up to 930 diameter which is no problem, but I am unsure about how far into the block is should go and need confirmation of the gear being equivalent.

I have taken a picture of a 930 distributor and listed the dimensions I am trying to confirm, namely the amount it sinks into the block, the OD and ID of helical drive gear.



For info, when I mocked up the marelli 2.2L distributor per the picture below, I estimated the dimension 'A' to be around 63mm based on sinking the unit into the block and feeling for the right backlash. It would lock up if pushed too far in (suggesting that the mesh happens above the centre line of the drive gear on the crank???)

For the marelli drive gear, I measured dimension B and C at 25mm and 17.3mm respectively, 12 tooth.



If anyone can confirm it would be most appreciated, thanks.

[Speedy Squirrel]

I happen to have mine out to do the same thing! Except I am using a Bosch distributor.

For your dimension A, I measured approximately 70mm:



The pinion on the 3.3L turbo is 12 teeth, 25.80 to 25.90 OD. I can't get a good ID measurement because of the chamfer on the gear ID, but it is around 12.5mm.

I measured the overall protrusion length from the mounting face to the pinion end at 90mm. The Bosch spec is 89mm. I can get to that by pushing the drive shaft all the way in to the distributor body.

[b930]

Thank you Speedy Squirrel,

I think it could work but am concerned about the drive gear itself. The OD seems to match but for some reason, it just does not feel right when inserted into the block, like it binds with the crank drive gear; I am thinking the depth of the distributor gear might be wrong. Can you possibly take a picture end on the 930 drive gear?? Here is the old marelli 2.2L one I have, if I put the jaws of a vernier across the root of teeth I get 17.3mm, somewhat different to your 12.5mm. Be good to see if there are any obvious gear pattern differences.



If we are talking about the same thing, and the gear root diameters are as different as the initial measurements suggest, then I think the teeth on the crank gear are bottoming out in the (larger diameter) root of the old marelli distributor gear. Anyone got a close up of stock 930 distributor mounted in block shown the main shaft / block interface to get an idea of how far it sinks in?

By the way, this is the mag pic up I am going to use, its a marelli unit used in the YB cosworth engine distributor for phase signal.

[Speedy Squirrel]

I measured it. The gear outer diameter is 25.80mm. The gear root diameter is 18.20mm. The ID of the gear mounting bore is 12.44mm. I think you need to worry about the insertion depth. For the Bosch it is 89mm.

[b930]

Excellent, the gears sound the same, I was taking your previous shaft bore dimension as gear root. Thanks for confirming, I think it will work.