Does anyone have an old distributor they can give/sell me??
Discussion
Right I've done some research and the cam sprocket trigger pattern is a bit complex so I've ordered a new one and will have some of the guys at work model it in cad and convert it to a disc much like dnb's. I'll get a bunch of them laser cut and hopefully we'll be good to go from next weekend!
I've decided that although it is more of a pain to install as the front cover has to come off, it is a simpler part to fabricate than a stubby dizzy with integral sensor and unequal rotor. Plus it's also a neater long term solution.
So thank you Hamish and Peter for your offers of dizzies but it looks like I won't require them now. If anyone else is thinking of a GEMS conversion please let me know if you'd like to ask anything, and obviously I will have a solution to the cam sensor issue.
I've decided that although it is more of a pain to install as the front cover has to come off, it is a simpler part to fabricate than a stubby dizzy with integral sensor and unequal rotor. Plus it's also a neater long term solution.
So thank you Hamish and Peter for your offers of dizzies but it looks like I won't require them now. If anyone else is thinking of a GEMS conversion please let me know if you'd like to ask anything, and obviously I will have a solution to the cam sensor issue.
Hi Nick
I'll certainly take one off your hands, I will share your development and material costs for the disc if you let me know what they are.
I'm sure you have this in mind already so hope you don’t mind me mentioning it; the centre hole of the disc needs to replicate the bore and keyway of the dizzy nose cam gear, so in effect a hybrid of the GEMS trigger pattern and the old dizzy style mounting arrangement.
I've attached a copy of Dave (DNB's) drawing which I have copied from his post on the British V8 forum. Dave hope you don't mind!
I suspect the keyway position is critical and based on my observations the keyways are about 90degrees different between the GEMS and Dizzy cam gear. I don’t know where I can get specific info to establish the actual angle difference so I plan to pop over to speak to Rob at V8D (he is only about 20 mins drive from me and he built my engine) and see if he can help with this figure.
What thickness material are you thinking of using? I had thought 3mm for rigidity and also to try and ensure that the CPS doesn’t sense the sections of the JP cam gear behind the disc which will be visible through the slots of the disc (but hopefully far enough away not to actuate the sensor).
I'll certainly take one off your hands, I will share your development and material costs for the disc if you let me know what they are.
I'm sure you have this in mind already so hope you don’t mind me mentioning it; the centre hole of the disc needs to replicate the bore and keyway of the dizzy nose cam gear, so in effect a hybrid of the GEMS trigger pattern and the old dizzy style mounting arrangement.
I've attached a copy of Dave (DNB's) drawing which I have copied from his post on the British V8 forum. Dave hope you don't mind!
I suspect the keyway position is critical and based on my observations the keyways are about 90degrees different between the GEMS and Dizzy cam gear. I don’t know where I can get specific info to establish the actual angle difference so I plan to pop over to speak to Rob at V8D (he is only about 20 mins drive from me and he built my engine) and see if he can help with this figure.
What thickness material are you thinking of using? I had thought 3mm for rigidity and also to try and ensure that the CPS doesn’t sense the sections of the JP cam gear behind the disc which will be visible through the slots of the disc (but hopefully far enough away not to actuate the sensor).
What have I started here.... 
I think you've got the main issues sorted out now. They are along the same lines a's the concerns I had. I have no problem with you using my drawings. With my ecu I can get away with the trigger tooth moving around a bit since it is only there to reset the cylinder counter. The main timing data comes from the crank. This may not be the case for GEMS so you'll need to be a bit more accurate than I was.
I think you've got the main issues sorted out now. They are along the same lines a's the concerns I had. I have no problem with you using my drawings. With my ecu I can get away with the trigger tooth moving around a bit since it is only there to reset the cylinder counter. The main timing data comes from the crank. This may not be the case for GEMS so you'll need to be a bit more accurate than I was.
Mike, if you could have a word with V8D that would be great! My primary plan is to have a look through the Land Rover RAVE manual that I have to find out how the small tooth is meant to be set relative to TDC of cylinder 1. I'll then work out where the keyway needs to be and place it accordingly. Like you say, a 3mm carbon steel plate should suffice, offset as far forward as is possible to avoid cross signals from the pulley behind. Other than that I guess it needs to be very much like David's lovely creation. I'll try and get the front of my engine apart this weekend (weather permitting as it's outside 
) then I'll hopefully have a clear run once the new cam sprocket turns up.
) then I'll hopefully have a clear run once the new cam sprocket turns up.Matthew Poxon said:
What is the advantage of doing all this work to convert to GEMS over a decent aftermarket ECU? I know Mark did mention something about self mapping last time I spoke to him?
Hi Matt!There are lots of good reasons...
- GEMS is self mapping (completely) - to the point where Mark reckons it maps cars better than he can so no more trips to the dyno
- Dual knock control, dual wideband lambda sensors, mean your engine is very safe in all conditions
- Full sequential fuelling (as most aftermarket ECUs now do)
- OEM - any aftermarket ECU will start with a blank set of tables which a mapper will have to set in ~1 day using a dyno (which can't replicate all driving conditions). GEMS was developed on the RV8 over a period of years at a cost of millions of pounds. The base maps have been tuned and refined to a full OEM standard - something you will never achieve with an aftermarket ECU. GEMS will give a more refined drive than anything else available unless you put in serious mapping time, and it is hugely over-engineered at a cost to Lucas-Sagem which aftermarket manufacturers could not dream of. This is particularly important on the knock maps - Lucas-Sagem will have I'm sure tested many engines to destruction to tune the knock sensing maps correctly.
- With an AFM, the measurement of air is much more precise, and allows the ECU to adapt to any conditions (eg mountains) - Mark even has these ECUs running in light aircraft with no modification - it will adapt to huge changes in pressure, temperature and all sorts and still run perfectly.
- CAN bus - GEMS is fully OBD compliant so you can take your car to any garage if it ever develops a fault and it has a full diagnostic system, including error histories so it can track intermittent faults. In addition you can plug in (as I have) a wi-fi OBD reader and can read/clear fault codes and read any of the ECU's parameters from your iphone/laptop/ipad etc in real time
- It is designed for a RV8. If you have the correct block, all of the necessary sensors simply bolt on to the existing bosses which were not used by TVR. And the parts are OEM range rover so very easy to source, and very cheap if you go for good quality second hand (there are millions of spares on Ebay)
- The ECU is waterproof! (hopefully not a benefit you'll need)
- If emissions laws ever change, you can add two more lambda sensors and a fuel tank pressure sensor and your car will be fully Euro 3 emissions compliant.
Edited by 450Nick on Friday 22 April 15:29
Matt
For me the attraction is;
All the benefits Nick has outlined plus
I have all the parts (mostly acquired for very low cost) apart from the Tornado chip
I have the 38A block in my Griff already, just need to fit a GEMS trigger flywheel (engine is internally balanced) and sort the cam trigger
I can pretty much install it all myself
Its a factory/manufacturer standard installation
The only other option I would consider is the MBE from TVR Power, I know they do impeccable work and it would be a first class job but I cant justify sinking £3k of investment into the car right now.
If I didn't already have the 38A block with the crank and knock sensor bosses already installed GEMS wouldn't be an option
For me the attraction is;
All the benefits Nick has outlined plus
I have all the parts (mostly acquired for very low cost) apart from the Tornado chip
I have the 38A block in my Griff already, just need to fit a GEMS trigger flywheel (engine is internally balanced) and sort the cam trigger
I can pretty much install it all myself
Its a factory/manufacturer standard installation
The only other option I would consider is the MBE from TVR Power, I know they do impeccable work and it would be a first class job but I cant justify sinking £3k of investment into the car right now.
If I didn't already have the 38A block with the crank and knock sensor bosses already installed GEMS wouldn't be an option
Many thanks for the detailed responses gents. Certainly sounds impressive and I shall look forward to hearing how you get on. I reckon combined with your SC that will be a really nice refined drive Nick. No pop and bang map though I presume like you had on the emerald.
I seem to remember my block being an older non-cross bolted version with no knock sensor bosses last time Mark looked at it.
I seem to remember my block being an older non-cross bolted version with no knock sensor bosses last time Mark looked at it.
Matthew Poxon said:
Many thanks for the detailed responses gents. Certainly sounds impressive and I shall look forward to hearing how you get on. I reckon combined with your SC that will be a really nice refined drive Nick. No pop and bang map though I presume like you had on the emerald.
I seem to remember my block being an older non-cross bolted version with no knock sensor bosses last time Mark looked at it.
Oh that is a shame Matt, though not the end of the world I don't think? I'm hoping for a very well sorted ECU, and having experienced the wild variation in feel of the car depending who's mapped it; I'm looking forward to seeing how it's supposed to drive from Rover's base maps. I'm sure it will still crackle a bit with the exhaust on but perhaps not the cannon fire of old (although we'll see what Mark can do...)I seem to remember my block being an older non-cross bolted version with no knock sensor bosses last time Mark looked at it.
450Nick said:
Oh that is a shame Matt, though not the end of the world I don't think? I'm hoping for a very well sorted ECU, and having experienced the wild variation in feel of the car depending who's mapped it; I'm looking forward to seeing how it's supposed to drive from Rover's base maps. I'm sure it will still crackle a bit with the exhaust on but perhaps not the cannon fire of old (although we'll see what Mark can do...)
I am looking forward to hearing your thoughts on the GEMS ECU especially as you have experience of 14CUX and Emerald. I know mine drives very nicely indeed on the old 14CUX mapped by Mark Adams, very complaint and well mannered, just a shame it relies on the dizzy for ignition.In theory GEMS should be the ultimate ECU for rover V8 considering the budget behind it. It does make me wonder how well an aftermarket ECU car would deal with uncommon environments such as high altitude where the air is much thinner. All of these situations would have been tested with an OEM product but perhaps not by the average tuning shop with aftermarket ECU. MAFM is also a very accurate way to control the fuelling which most aftermarket ECUs do not use.
I think Mark is missing a trick by not offering a GEMS drive in drive out conversion, compelete with new loom.
Matthew Poxon said:
I am looking forward to hearing your thoughts on the GEMS ECU especially as you have experience of 14CUX and Emerald. I know mine drives very nicely indeed on the old 14CUX mapped by Mark Adams, very complaint and well mannered, just a shame it relies on the dizzy for ignition.
In theory GEMS should be the ultimate ECU for rover V8 considering the budget behind it. It does make me wonder how well an aftermarket ECU car would deal with uncommon environments such as high altitude where the air is much thinner. All of these situations would have been tested with an OEM product but perhaps not by the average tuning shop with aftermarket ECU. MAFM is also a very accurate way to control the fuelling which most aftermarket ECUs do not use.
I think Mark is missing a trick by not offering a GEMS drive in drive out conversion, compelete with new loom.
It's not just thin air, its all sorts of situations which can't been replicated on the dyno such as low speed, low temperature starts, hot starts with hot fuel, light throttle when descending down a hill (particularly on motorways); these have always been bugbears of aftermarket ECUs. The high end ones are certainly capable of catering for the situations, but the maps need lots of work to cover this and I'm sure no one is prepared to pay for a tuner to sit in the car with them for 6 months ironing it all out! This is the benefit of an OEM ECU with OEM maps. The only issue with them is they can be a bit of a faff to implement and very few people can unlock them for use. In theory GEMS should be the ultimate ECU for rover V8 considering the budget behind it. It does make me wonder how well an aftermarket ECU car would deal with uncommon environments such as high altitude where the air is much thinner. All of these situations would have been tested with an OEM product but perhaps not by the average tuning shop with aftermarket ECU. MAFM is also a very accurate way to control the fuelling which most aftermarket ECUs do not use.
I think Mark is missing a trick by not offering a GEMS drive in drive out conversion, compelete with new loom.
I wouldn't be surprised at all if Mark does do a kit, but he is pretty well limited on time so I've no idea when he'll get around to it; I will try and collect together a sort of guide of what I did so at least people can get an idea of what's involve and the parts required then perhaps Mark can look at supplying the bits for people or garages to do themselves. We'll see once I've ironed the kinks out of mine I guess
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