Getting sync from a cam lobe???

[Chris Wilson]

I have done a few M800 installs, and am about to put mine on a B230 Volvo turbo red block engine. In discussion on a Volvo forum someone said they got sync from a Hall effect sensor looking at a cam lobe! The sensor being mounted in a welded on boss in the alloy SOHC cover. Someone else chimed in saying they were getting a sync pulse from a Hall effect sensor looking at the redundant mechanical fuel pump lobe on the half engine speed layshaft for the disi / fuel pump / oil pump drive. I believe they were both using Megasquirt. Is this feasible or recommended? Surely a cam lobe does not have a well enough defined edge for satisfactory operation of even a Hall effect sensor?

As an aside, I will be getting the crank signal from a lightweight version of the stock flywheel and magnetic sensor. 60 minus 2 "dimples" in the periphery, stock mag sensor and bracketry. Anyone got a neat way of getting a sync? I prefer Hall effect for this. I thought of using a peg in the layshaft, in a turned down section that would have been the mechanical fuel pump lobe, but the late oil squirter blocks do not have a hole in the block casting for a mechanical pump. I guess I could bore one... Any other neat ideas? Thanks.

[Sean]

Really just depends on how well defined the lobe is.... I have done it with on motorcycle engines. The big GSX engines have quite pointy lobes with aftermarket cams, so it works Got a picture of a typical cam and/or lobe for one of these Volvo engines?

[stevieturbo]

Could you drill and tap an allen key bolt into the camshaft somewhere, as it would be more defined ?

As a temporary basis on my LS a couple of years ago, I used a hall sensor pointed at one of the valve rockers for a phase trigger. I was going to use the spring, but it was easier to point directly at the roller tip of the rocker itself.

Whilst it did work, it was a little unreliable, but I opted to ignore cam trigger once it was sync'd up so it wasnt an issue.
Not sure if Motec allows you to do that or not though.

Could you adapt or weld a little tooth onto the upper cam wheel and fit a sensor into the cam cover somewhere ?

[harky]

I used a cam lobe on a Kawasaki GPZ 1100 ( 1982)
The standard lobe was very " pointy " and worked fine to 9500 rpm
When I changed cams to a lot more broader profile I had poor sync , especially @ high rpm
I fitted a tab to the cam sprocket to get good sync
So the answer is yes you can get a sync from a cam lobe , profile and rpm dependant
I was using a hall sensor
Cheers
Harky

[super7]

You can use the original equipment distributor which is mounted on the block and take the signal from the Hall sensor.

Sincerely, Nils-Erik

[stevieturbo]

Good thinking.

My Volvo still uses a dizzy and cap at the rear of the cylinder head which is running directly off the cam, so it probably wouldnt be too difficult to adapt something back there

Not sure which engine model mine is, 1997 940 turbo.

[Chris Wilson]

Mine has the distributor on the back of the head, too. It merely distributes HT though, no sensor within. I am planning on trying a few different heads I have and some do not have provision for the rear of head disi. I think I will use the hole for the mechanical fuel pump on the side of the block. Some blocks not using a fuel pump have a blanking plate here, some do not have the casting drilled at all. My blocks have the hole, so no boring needed. The low pressure carburettor pump was driven off a cam lobe on the auxiliary shaft, which rotates, like the cam, at half crankshaft RPM. I have machined the lobe off a spare shaft and I think things can be made to work by drilling and tapping the now round "lobe" for a steel peg, and mounting a Hall effect sensor on the pump hole blanking plate. I will start another thread, but I will need a Hall sensor that will run in a hot engine oil environment and has provision to seal into or against the flat blanking plate. I have used Bosch 0 232 103 022 sensors in the past, but these have been in fresh air. I am not sure whether they would like or even tolerate a hot, wet oily environment. I work on lots of 2JZ-GTE Supra twin turbo engines and these have 2 cam position sensors that pick up off pegs cast into the intake cam, and run bathed in hot oil on the engine side, within the cam box of the head. I think they are magnetic, not Hall effect though, and are rather big. They are also very expensive, new.

Has anyone any ideas for a Hall sensor that is happy with half of itself in hot oil, can be sealed to a flat surface, and is reasonably priced and easily sourced? Ford TDCi ones seem to look as if they are designed to run in oil, and are cheap. Are they Hall effect though?

Thanks.

[stevieturbo]

generally speaking if they are 3 wire they are hall.

There is no sensor in the dizzy cap, adapt and overcome.

I ran a sensor like this ( not sure if it was exactly this one, but very similar ) when I had it screwed into the valve cover pointing at the rocker

http://www.rapidonline.com/Electronic-C ... pe-63-4655

There are various versions of sensors like this though. As to how well it will seal though...supposed depends on sealer used on the threads