Does anyone have an old distributor they can give/sell me??
Discussion
If you have a Serp engine, I might have a better option than a redesigned dizzy.
This is a balanced cam sensor disc as fitted to my Griff to give one pulse per cam rotation to synchronise the engine. It requires a common Honeywell hall sensor fitted in the space designed for it in the timing cover.
This is a balanced cam sensor disc as fitted to my Griff to give one pulse per cam rotation to synchronise the engine. It requires a common Honeywell hall sensor fitted in the space designed for it in the timing cover.
Edited by dnb on Tuesday 19th April 22:53
Bluebottle said:
Hi Nick 
MA told me you were going gems, and to have a chat with you about it.
If you don't get Peter's, i still have your old one in a box somewhere. drop me a mail if you need it
Hi Hamish! Yes I'm going GEMS; its taken a fair bit of thought to get the right bits in place, but with lots of preparatory work done up front, the actual conversion is now going together pretty simply. I have the full loom in the car now and all connected up, the only thing I'm missing is a cam sensor and I'm now torn over whether to go for a modified dizzy or a front cover/trigger wheel mod. MA told me you were going gems, and to have a chat with you about it.If you don't get Peter's, i still have your old one in a box somewhere. drop me a mail if you need it
Edited by Bluebottle on Wednesday 20th April 12:30
I'll drop you a mail anyway now...
dnb said:
If you have a Serp engine, I might have a better option than a redesigned dizzy.
This is a balanced cam sensor disc as fitted to my Griff to give one pulse per cam rotation to synchronise the engine. It requires a common Honeywell hall sensor fitted in the space designed for it in the timing cover.
I'm also progressing to a GEMS conversion as I already have a 38A block with knock and crank sensor bosses. I have most of the components lined up which I either had from an old P38 Rangie or have picked from eBay but nothing installed yet. This is a balanced cam sensor disc as fitted to my Griff to give one pulse per cam rotation to synchronise the engine. It requires a common Honeywell hall sensor fitted in the space designed for it in the timing cover.
Edited by dnb on Tuesday 19th April 22:53
The dilemma I have is I have a stealth cam which is only 2 or 3k miles old and I don't want to change it just to get a GEMS nose cam and timing gear.
DNB your solution looks good and is similar to an idea I have been toying with but I understand the GEMS ecu requires 1 short and 3 long pulses per revolution, hence the form of the GEMS timing gear;
image courtesy of RPI.I guess your solution would work but the plate would need to have the trigger lobes as the GEMS gear. Does any one know how close the end of the sensor has to be to the trigger plate?
What clearance do you have from the face of your trigger plate to the alloy tube inside the timing cover that holds the dizzy? Does the alloy tube cast into the timing cover need to be relieved to allow your plate with the bolt head trigger to pass?
Taking your questions in order:
Yes, I'd have to redraw the disc to have lobes as the GEMS gear. I am not sure if the GEMS needs a single pulse from each transition or whether it monitors the whole length of the slots. If it needs slots, this presents a little problem because the honeywell sensor is too short to see slots in the disc. There is nothing stopping the entire disc being spaced away from the cam pulley by thinning down a pair of cam spacers to make a disc sandwich. The sensor has to be approximately 2mm away from the disc.
There is a few mm clearance from the disc itself to the timing cover tube. However there is no clearance for the pin/bolt head. Therefore a small section does need to be removed from the tube. I took a photo but have not found it yet.
Yes, I'd have to redraw the disc to have lobes as the GEMS gear. I am not sure if the GEMS needs a single pulse from each transition or whether it monitors the whole length of the slots. If it needs slots, this presents a little problem because the honeywell sensor is too short to see slots in the disc. There is nothing stopping the entire disc being spaced away from the cam pulley by thinning down a pair of cam spacers to make a disc sandwich. The sensor has to be approximately 2mm away from the disc.
There is a few mm clearance from the disc itself to the timing cover tube. However there is no clearance for the pin/bolt head. Therefore a small section does need to be removed from the tube. I took a photo but have not found it yet.
Hi David, sorry I've been trying to get hold of Mark A to confirm the trigger requirements for GEMS but it does appear as Micheal has said above that it requires 3 short and one long pulse and these are fairly specific lengths.
In principle the method will work but like you say, it will require a completely different disc. Michael, perhaps you would like to drop me an email as we could probably benefit by joining our efforts!
I'm a little further along now and have all sensors and loom in and tested, I just need the cam sensor and to connect my ECU loom to my car loom (a couple more hours worth of work). If you would like any tips or to discuss plans then give me a shout..
In principle the method will work but like you say, it will require a completely different disc. Michael, perhaps you would like to drop me an email as we could probably benefit by joining our efforts!
I'm a little further along now and have all sensors and loom in and tested, I just need the cam sensor and to connect my ECU loom to my car loom (a couple more hours worth of work). If you would like any tips or to discuss plans then give me a shout..
Hi Nick
PM sent.
The next stage in my plan is to acquire an old GEMS gear to measure and produce an Autocad drawing of a suitable disc.
As Dave's install I have a JP timing gear. I don't think this will work with a vernier gear for instance. If you don't have the JP gear might be worth persuing the dizzy mod otherwise you will have to change the cam gear to JP type.
As I understand the trigger requirements the ecu needs 1 short and 3 long pulses, so the sensor must detect the solid part of the gear and it must also measure the duration otherwise there would be no need for the different length sections around the gear. Not sure how you would replicate this inside the dizzy body.
I think the disc can be made flat like Dave's solution and use the NAS Defender spec cps which MA tells me is longer than the standard P38 GEMS cps and so this should reach to within 2mm of the trigger disc? The only drawback is the NSC100840 part is quite a bit more expensive than the Honeywell item Dave has used.
I'm happy to collaborate in a cam gear solution but it sounds like you're much further advanced than me and work keeps getting in the way of my plans call or email so we can discuss further.
Cheers
Mike
PM sent.
The next stage in my plan is to acquire an old GEMS gear to measure and produce an Autocad drawing of a suitable disc.
As Dave's install I have a JP timing gear. I don't think this will work with a vernier gear for instance. If you don't have the JP gear might be worth persuing the dizzy mod otherwise you will have to change the cam gear to JP type.
As I understand the trigger requirements the ecu needs 1 short and 3 long pulses, so the sensor must detect the solid part of the gear and it must also measure the duration otherwise there would be no need for the different length sections around the gear. Not sure how you would replicate this inside the dizzy body.
I think the disc can be made flat like Dave's solution and use the NAS Defender spec cps which MA tells me is longer than the standard P38 GEMS cps and so this should reach to within 2mm of the trigger disc? The only drawback is the NSC100840 part is quite a bit more expensive than the Honeywell item Dave has used.
I'm happy to collaborate in a cam gear solution but it sounds like you're much further advanced than me and work keeps getting in the way of my plans call or email so we can discuss further.
Cheers
Mike
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