The V8 Owners Forum -

Hello all,

I want to have a bespoke camshaft sprocket made for my VEMS setup.

Anyone know what materials going to be best.

cheers

scott

If you have a vernier you only need to make the central part, any magnetic steel will do if the aim is to have a cam phase sensor.

The sprockets we make are in EN8.

thanks...

just gotta decide now at what angle to make the trigger point on the sprocket....

Then see i can get one made somewhere.

cheers

scott

having a sprocket made is a bit extreme for getting a cam position sensor?
can you not use an dizzy ?

hello eliot,

I am using an intermediate front cover with a piper 285 cam, and currently a GEMS camshaft sprocket.

So i dont have any facility to use a dizzy as theres, no camshaft drive.

The GEMS sprocket give me 4 pulses (2 short & 2 long) but the vems cannot use this.

So thought best just to replace it with a bespoke one.

Think i need one pulse either at TDC or just before to make the VEMS work with secondry triggering.

Still its work in progress...

scott

Surely the angle doesn't really matter as you set it in software, balance is the only consideration so opposite the keyway if a missing tooth or adjacent if a missed drilling (holes at 10 deg increments). I'm not sure how many catch in less than 2 revolutions so fancy predictive patterns always seem a bit over complex to me?

here is what i currently have, that works on the 4.6 v8 GEMS efi engine.

http://www.turnerengineering.co.uk/acat ... o_363.html

And i want to make a new one with one pulse somehwere between TDC and before TDC.

As my VEMS ecu only allows for one trigger when using camsync.....

Not sure if there's any benefit from this other that it works.

scott

Hi,
the N-1 type timing sprocket has the advantage that the electronics can lock up more quickly to any changes to pulse rate than one pulse per revolution. Realistically an engine with one pulse pre cam revolution will take 6 revolutions of the engine to workout where the pulse is on start up as opposed to an n-1 approach which can work it out in just over 2. When engine revs change, once the engine is running, it can see that change in 1440/n degrees, so for a 36 tooth wheel that is 40 degrees, as opposed to a 1 pulse set up that will take atleast 4 revolutions of the engine.
Best regards
Mike

What sort of sensor is it?
With the new sprocket, what was you going to leave a hole or something?
Could you not make up some filler pieces out of ~3mm steel and tig weld them in to fill the gaps up?

kiwicar wrote:Hi,
the N-1 type timing sprocket has the advantage that the electronics can lock up more quickly to any changes to pulse rate than one pulse per revolution. Realistically an engine with one pulse pre cam revolution will take 6 revolutions of the engine to workout where the pulse is on start up as opposed to an n-1 approach which can work it out in just over 2. When engine revs change, once the engine is running, it can see that change in 1440/n degrees, so for a 36 tooth wheel that is 40 degrees, as opposed to a 1 pulse set up that will take atleast 4 revolutions of the engine.
Best regards
Mike

It's not a crank sensor or a cam sensor as such - the crank trigger is doing that - it simply needs to give the phase the crank is on.

machine up bits of steel to fill the holes you don't want and solder them in place. You wont put enough heat into the sprocket to change the temper with soldering. Other alternative is to machine out the holes so you get 4 even pulses. What configuration does VEMS need? It cant be just one pulse as that would leave just one part holding the outer to the inner of the sprocket. Its the metal that creates the pulse not the hole unless of course it can accept one long pulse?

yes i thought of making some filler pieces, but am worried about welding them in as the original gems sprocket looks like a cheap cast material.

And i thought it either might be a poor weld or crack or even distort during welding.

I've got one to try and might do this yet.

Its all still at the decision stage so all ideas are welcome.

cheers

scott

if the filler pieces are well made and fit closely, a few small tacks with a tig welder wont cause any problems.
Certainly attacking it with a mig welder on full blast laying down massive beads may well get a little too much heat into it.

What about making a round plate that goes over the whole sprocket, held on with the central bolt hole with a small dowel to stop it rotating?

Out of interest if its an intermediate cover, do you really want to get locked in to the different P38 cam noses and timing gear?