Rover v8 cam sync sensor disc - Rob may be able to help :)

[dnb]

I'm looking at removing my dizzy based cam sensor while I change the cam.
This means either being "normal" and having wasted spark etc, or getting a cam sync disc laser cut to fit where the dizzy drive gear should be, plus some shims to hold it in the right place for the sensor.

Note that I have a "Serpentine" Rover engine (often called "intermediate" as it still has the dizzy, and has the later crank driven oil pump) so there is a sensor boss already cast into the timing cover, but it's blanked off.  I can't easily fit the later Bosch timing cover as this causes mayhem with the sump, water pump, oil filter, having to lose the duplex timing chain etc...
 
If I drew up a nice drawing, would it be possible to get this cut in the same way as the Nissan trigger discs?

Thanks

[rob@vems.co.uk]

Yes.
The main issue I had was caused by the thickness of the stock disk (~0.2mm) and the fact that the majority of laser cutters only held stock of 0.8 to 1mm thick and I kept hearing talk of "We'll have to get that in and that will cost you more etc"
So if you can make it thick enough it will be simple.

Expect minimum orders of ten though, one disk will cost you around £60 , 10 disks will cost around £6 each!

Rob

[dnb]

Thicker is better for me in this case - it'll mean less shims to make up the thickness of the dizzy drive.

MOQ of £60 isn't too bad - I expect that with all these things, the time is in the setup, not in the actual production.  I dare say they'll sell eventually - Mike, Jools & I are slowly convincing the UK Griff owners that aftermarket ECUs are the way to go...  It's a small step to sequential operation then

Would something in TurboCad or DXF format be OK?

[rob@vems.co.uk]

I know who you are but who are Mike and Jools, and why are they not on the forum!?!

Once you get to a millimeter or two it might just be easier to machine, rather than laser cut them, which is easily done.

DXF, Turbocad or any format is fine, I'll stick them onto a CAM package to help reduce costs.

Rob

[dnb]

Mike is currently putting an AJP8 engine in his Griff - so will be fitting an Emerald ECU.  Nothing doing with VEMS since the engine is a flat plane crank v8 with weird firing sequence.  He had a very modified Rover running on an Omex in there up to last week - 354bhp from 5 litres, still NA.   

Jools is a Cerbera tuner with a good reputation.  He's branching out into Griffiths (He mapped Mike's car) now and I'm due there shortly for him to supply & set up the new suspension and for some playing on the rollers.

[dnb]

I should have said - around 1mm is fine.  Since this is going to be basically an unbalanced load on the cam, I want to keep it as thin as possible, but also want it thick enough to not be a problem with it triggering properly or getting distorted by anything - it'll be getting splashed by oil etc as it's inside the timing cover.

[Agriv8]

If you have a .DFX  file I can have a chat to a mate who has a CNC plasma cutter he cuts 2mm or 3mm ali for the pannels for the kit cars I am sure I can get him to run a development one or two off. I know he has cut trigger wheels for spedo drives.

No promises but I can investigate if required. Was thinking about this route myself ( perhaps I should concentrate on getting the bits I have got working first  ). If it is small > 100mm dia this can be done using off cuts of ali. What sort of tolerances do you recon you require.

Will hope to see him Tue eve so let me know.

Regards Agriv8

[dnb]

Thanks for the offer - it would be good to have a few more sequentially triggered cars   I'm looking at approx 70mm dia, however the material needs to be ferrous so the hall sensor works.

Not worked out tolerances yet, but I'd like it to be pretty tight as it's going to be rotating at up to 3,500RPM (maybe even 4000 if I get my way)

 

[Agriv8]

dont know what size he goes down to steel wise ( 2mm 3mm ) perhaps and upto 10mm.

Will have a chat and see what sort of tolerances he can get down to .

But the offer stands if you want one to prove a theory and have a .dfx file let me know. I am actually upgrading the CNC plasma PC for him this evening, So may have a play seeing what scrap I can create ...

Regards

Agriv8

[dnb]

Having had a good look at the nicely cleaned timing cover and cam last night, there is quite a bit more room than I thought for a thicker wheel.  However, the thicker I make it, the more carefully I have to design the wheel to keep it balanced.  Not a problem - just more thinking time!

[rob@vems.co.uk]

Have you checked the Honeywell 1GT1 sensor datasheet?  That will give good advice on the material thickness.
Remember that the cam runs at half crank speed and that a bit of counter balancing or a well placed hole will eqaul the weight of the tooth.
I have a CAD program that will identify the centre of gravity of a peice.

Rob

[dnb]

I was going for a solid disc with a single hole in it for the trigger (so it is a falling edge trigger, although it doesn't really matter because a hole still has 2 edges).  To balance, I was going to make other holes in the disc that aren't near the trigger hole. 

Not read the datasheet, but from experience, 2mm thickness should be plenty for the sensor to see.

The thing to determine COG would be very useful - it'll save me doing some really nasty integrals...