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Dec 20, 2020 16:01:42 GMT
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With that all sorted I went to fire up on the DTA. I just copied the same 2D advance curve (15* idle) and trigger offset (115* BTDC) I had previously run with the NODIZ so expected it to just work. Interestingly this was not the case... instead I got lots of coughing through the carb indicating a lot of advance. I dropped the timing to 0* BTDC and it started and ran, but not that happily. Dropping the trigger offset improved matters and at 80* it was running well enough to get the timing light on. Set to 2 stroke / wasted spark I ended up at 60* BTDC and an engine running very happily indeed - and me feeling a bit confused. Hopefully more will follow very soon. James At least on Megasquirts you have to put advance on 0° and let the ECU do the tune from there. You are running stock cams? |
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Dec 30, 2020 18:52:59 GMT
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samulis - I have been running the standard 1,3 cams but will be fitting some 774 rally cams when it all goes back together, the head is away being skimmed and ported which will bump the compression from 9,5:1 to 11,5:1. Since last time it has started to feel like a bit of an uphill struggle. When I came to fit the new adaptor plate onto a block with dowels and all the fasteners it became apparent something was very wrong, several holes were 4 or 5mm out of position. Overlaying it onto a 1:1 print revealed that the entire form was distorted around the starter motor recess, splaying out. I suspect this was due to stress in the steel so popped the plate in the press. Carefully manipulating it got the dowel holes in the block to line up, along with some of the bolt holes. However, holes that had lined up now didn't... I need to discuss the issue with the supplier when they are back next week as it appears that not all of the holes were cut before the outer profile was cut. The A-Series version was a complete ring so was more stable. I think moving forward I will abandon fully laser cutting the plate and either have a cut profile with milled holes or a fully milled part, depending on cost.  Not to be deterred I carried on with a trial fit in the car with the dummy block  Gearbox in.  Followed by the block. It is so light I can lower it in with one hand!  Gear stick looks to be in the right place but is a bit tight. I will trim the housing a bit and probably move it forward 10mm to get a bit more clearance.  Underneath there are no issues at all. Success! Significantly less successful was the discovery that the flywheel doesn't fit in the bellhousing! When I first started researching the conversion I was looking at using a later R7ME Jimny gearbox from the twincam M13A engined cars. I was given a drawing of the bell housing profile by a very helpful member of the bigjimny forum which had ample clearance for the Micra (and A-Series) flywheel. However I found that the R7ME box was quite rare as it was quickly replaced with a R72 box, which is much more fragile. This puts the R7ME into higher demand in Jimny circles wanting to upgrade. To counter this I decided to use the earlier G13BB gearbox which is almost identical externally but with a slightly different starter motor position and bell housing hole pattern. What I failed to notice was the smaller bell housing casting!   The flywheel I am using has a standard ring gear and a smaller set of teeth for crank position sensing. The CPS teeth are size for size with the bell housing so I was able to get clearance quite easily with a carbide.  This just leaves the starter ring gear. This is too large to grind clearance for without compromising the strength of the box. However, it only protrudes by 3mm above the adaptor plate.   This leaves me with two options Option 1 - Modified FlywheelMill 5mm from the crank mating face of the flywheel. This would pull the flywheel further into the adaptor plate clearing the bell housing and would be a pretty simple modification to make. This would result in a problem with the clutch plate not being fully engaged on the input shaft splines.  Clutch plate (green) is not properly engaged on the splines. Having the clutch this close to the engine also means that it is not possible to use the Suzuki clutch release bearing as the guide tube is not long enough This could be resolved by spacing the entire clutch assembly out further towards the gearbox with a plate  What this ends up with is a functional setup with a lot of custom parts, a huge amount of rotating inertia and a hodgepodge of parts (modified Nissan flywheel, Mazda clutch plate, Nissan clutch cover, Suzuki release bearing, custom spacer, custom spigot bearing carrier etc etc). Option 2 - Custom FlywheelThis can be machined with a reduced diameter crank sensor cut outs, a thinner starter ring gear closer to the engine and the clutch spaced closer to the gearbox. It also gives me freedom to incorporate the spigot bearing location into the flywheel and use any clutch combination I like. This would mean I could run an entirely Suzuki set up (cover plate, pressure plate and release bearing). It is also a chance to optimise the design for reduced inertia. It will also be expensive    I think my next step is a careful costing exercise and some more market research into whether this is likely to be commercially viable. I had a good amount of interest in the Nissan engine swap but no takers with most feedback asking for a 5 speed gearbox to go with it. This does solve that issue but I am unsure whether it will be cost effective still. Thanks for looking James
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mk2cossie
Club Retro Rides Member
Posts: 3,061 
Club RR Member Number: 77
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Dec 30, 2020 20:05:27 GMT
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I'd personally go with the custom flywheel setup, and speak to TTV about a one off flywheel made to your spec  From previous experiences with friends who have used them, they are pretty well priced for what they do, and may even have something on the shelf for that engine already that could be tweaked  |
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Drizz
Part of things
Posts: 337
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TTV for sure!
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MGF VVC 160
MG Midget
Metro Turbo
200 BRM
Range Rover Classic TD5
Discovery Premium 300TDi
Defender 90
Rover 420 GSi Sport Turbo
Discovery Extreme 300TDi
Range Rover P38
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Dec 31, 2020 10:18:35 GMT
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Another happy TTV customer here. However as you are considering a thinner ring gear on the custom flywheel, why not thin down the existing one. Could even combine with taking 1 to 1.5mm off the back of the flywheel if needed. I would also consider the cost of flywheel vs. the extra cost of the correct gearbox. Would make your conversion kit a lot cheaper if you werent supplying a flywheel.  |
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bstardchild
Club Retro Rides Member
Posts: 14,971
Club RR Member Number: 71
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Dec 31, 2020 10:41:59 GMT
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Another happy TTV customer here - they made a group of us Flywheels which used a std Monza Friction plate, Audi S3 pressure plate and release bearing to fit a bold pattern of a Lotus Carlton Crankshaft (and we all wanted different weights as one was for road car and one road and track and one pure track ) |
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Dec 31, 2020 10:43:00 GMT
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Looks like I will be giving TTV a call on Monday... procrastinator - it is a balancing act with this decision. The larger R7ME boxes tend to go for around £250 compared to about £100 for the G13BB version. As far as I can tell they are internally identical. While this does solve the issue of flywheel clearance it doesn't solve the clutch issue. I would still be running parts from 3 different cars and would still have the clutch release bearing problem to solve. As far as it goes for the kit it simplifies things a fair bit as it is not necessary to source a used coil pack type flywheel and I only need to supply a single clutch kit rather than parts from several. You are right that it would bring the cost of the kit down but I am not sure it would actually reduce the cost of the full conversion. I am going to wait until I have costs for a flywheel before working out whether I am sending good money after bad by not just getting the larger gearbox James |
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Jan 18, 2021 20:21:59 GMT
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James, Stellar work sir, great posts with excellent photos. I just finished reading this thread and if I lived in the UK I would be hoping to get your kit in the post. I wish you good luck in your business and hope you will soon post again on progress with the spridget. I love the Nissan engine with it's BMC heritage and progress that I do not associate with the BMC.
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Jan 19, 2021 12:28:09 GMT
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James, Stellar work sir, great posts with excellent photos. I just finished reading this thread and if I lived in the UK I would be hoping to get your kit in the post. I wish you good luck in your business and hope you will soon post again on progress with the spridget. I love the Nissan engine with it's BMC heritage and progress that I do not associate with the BMC. Thank you for the kind words. I am more than happy to ship internationally, send me a PM or email if you are interested. A decent update in the pipelines... James |
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Feb 10, 2021 17:50:09 GMT
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Hi
Anything new with Midget?
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Feb 11, 2021 22:10:37 GMT
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As promised, here is an update on progress. Gearbox wise I decided to make a bit of a U-turn after costing everything up and purchased an R7ME gearbox the day before lockdown. This box is a bit more expensive compared to the earlier G13B version but has a larger bellhousing. Other than the bellhousing the only other difference I have found is the spigot bearing journal on the input shaft, which is larger. The changes were made to make the transmission compatible with the more modern M13A engine.   Externally the R7ME is almost identical, the bellhousing is the giveaway with a lot more holes. Changing gearbox meant a new adaptor plate was needed. After the trouble I had with the laser cut steel plate I have decided to move to CNC machined plates from 6082 aluminium. This is also the case for the ribcase kits I am selling, but more on those later...   And mounted to the engine  I will need to modify this plate to accept a clutch slave cylinder / cable further down the line   Sucess!  A small amount of material will need to be ground to clear the Nissan starter motor. The top hole in the starter is threaded. In this corner every existing hole in both the engine block and gearbox seemed to be occupying the same place but was half a diameter out of position so I will drill a new hole in the bellhousing which will fall between the two original holes and align with the starter motor.  I am pretty pleased with this solution. The change to CNC machined aluminium gives a big improvement in accuracy and consistency and also reduces mass by 1.7kg! Next step is another trial fit before getting the shift housing TIGed and having a new prop shaft made up. I am itching to get back on the road but given current circumstances (weather and otherwise) I taking my time and trying to just get it right. In other news I took the plunge and have now officially launch the rib case version of the kit to market. I have several provisional orders and production parts are starting to arrive. First on site was a batch of CNC turned parts including crankshaft bolts, idler studs and some spigot bearing carriers.    Thermostat housing assemblies also together  Finally I received some very exciting news today, the first of a production run of manifolds are well under way, a huge improvement on my efforts!  More parts are due shortly and I should be ready to start dispatching kits in the next few weeks. Thanks for looking James |
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Last Edit: Mar 19, 2021 13:20:50 GMT by metroman
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A truly impressive project. I can appreciate you'll not want to run before walking, but I'm sure the kit would find interest in Spitfire circles, albeit with a few model-specific changes.
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Mar 19, 2021 13:15:55 GMT
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A huge milestone has now been reached for the project - complete kits are now in stock and ready to ship! I won't go into too much detail because this thread isn't about advertising and all the information is on my website but I will share a couple of photos that I think came out well.   Getting everything ordered, inspected and ready to go has taken up a lot of time which can now be spent on the car again. This has been focused around getting the engine back together. The original plan was to rebuild with a ported and skimmed cylinder head and some performance camshafts, with the intention of hitting 10.5 - 11:1 compression and making some decent power. However the head is taking a bit long than expected and I am also being asked a lot about the performance of a standard engine by potential customers. The standard power of 75bhp for a CG13 is not terribly appealing and while it is generally accepted in the Micra tuning community that the manifolds and exhausts are major restrictors for performance it is a hard sell without having actual numbers to back this up. To address this I have bought a late (coil pack) CG10 head, simply because it was the cheapest one on eBay. As far as I can tell there is very little, if any difference with porting or compression compared to a CG13 head.  New head gasket went on, followed by the cleaned up head with care taken to follow the 4 stage torque/angle process.  Next up will be fitting the marginally higher lift CG13 camshafts and checking the timing. On the gearbox side I have had a drill jig 3D printed to help get the hole for the starter motor in the right place and the shifter housing has been welded up. A hybrid prop shaft is also on order.    And finally one of the biggest improvements over the last build will be the exhaust manifold. I think it looks great!  More to come soon Thanks for looking James |
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Last Edit: Mar 19, 2021 13:21:49 GMT by metroman
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Mar 19, 2021 14:10:53 GMT
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Have you considered doing a version to replace the 1500 Triumph unit in the Midget?
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Mar 19, 2021 14:29:52 GMT
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A truly impressive project. I can appreciate you'll not want to run before walking, but I'm sure the kit would find interest in Spitfire circles, albeit with a few model-specific changes. Sorry for missing your post - it is something I would consider but probably not for a little while! dukethrust - the chassis are the same as far as engine and gearbox mounting points go between A-Series and 1500 cars so the kits will work for a 1500. The current kit would need an A-Series 'ribcase' gearbox and the 5 speed version will work with both. James |
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Paul Y
Posted a lot
Posts: 1,951
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Mar 19, 2021 15:27:11 GMT
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A huge milestone has now been reached for the project - complete kits are now in stock and ready to ship! I won't go into too much detail because this thread isn't about advertising and all the information is on my website but I will share a couple of photos that I think came out well. Getting everything ordered, inspected and ready to go has taken up a lot of time which can now be spent on the car again. This has been focused around getting the engine back together. The original plan was to rebuild with a ported and skimmed cylinder head and some performance camshafts, with the intention of hitting 10.5 - 11:1 compression and making some decent power. However the head is taking a bit long than expected and I am also being asked a lot about the performance of a standard engine by potential customers. The standard power of 75bhp for a CG13 is not terribly appealing and while it is generally accepted in the Micra tuning community that the manifolds and exhausts are major restrictors for performance it is a hard sell without having actual numbers to back this up. To address this I have bought a late (coil pack) CG10 head, simply because it was the cheapest one on eBay. As far as I can tell there is very little, if any difference with porting or compression compared to a CG13 head. New head gasket went on, followed by the cleaned up head with care taken to follow the 4 stage torque/angle process. Next up will be fitting the marginally higher lift CG13 camshafts and checking the timing. On the gearbox side I have had a drill jig 3D printed to help get the hole for the starter motor in the right place and the shifter housing has been welded up. A hybrid prop shaft is also on order. And finally one of the biggest improvements over the last build will be the exhaust manifold. I think it looks great! More to come soon Thanks for looking James That is really smart. Well thought out kit you should take a bow Sir! P. |
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Mar 22, 2021 22:45:26 GMT
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Thank you Paul Y , very kind I managed to get a few hours over the weekend and this evening in the workshop which has moved things forward a bit. The valves are now shimmed to suit a set of CG13 cams and the timing set using the factory method of aligning dots rather than 'properly' with a DTI and wheel. As said above, this build is to be representative of a completely standard engine and help put to bed the argument that the conversion is pointless as it doesn't make enough power...  This was capped with a fresh satin finish cam cover. The crinkle finish cover is for the distributor head so doesn't fit. With the Nissan Twin Cam lettering painted silver I think it will look reasonably smart.  With an alignment tool turned up over the weekend I was able to fit the clutch assembly. For this build I have a Micra cover and Mazda 323 friction plate. The Micra cover is designed for a 180mm plate with a different set of input shaft splines to the Suzuki box. Helpfully the Suzuki box has the same splines as the 184mm Mazda plate which fits nicely. With the engine basically back together I turned my attention to the gearbox.  The 3D printed drill jig was bolted on with some tube pressed in to protect the plastic from the bit. The holes are undersized with spigots on the back face to more accurately and securely locate in the existing holes in the bellhousing.    Worked a charm Hopefully more to follow soon Thanks for looking James |
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mk2cossie
Club Retro Rides Member
Posts: 3,061
Club RR Member Number: 77
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Mar 22, 2021 22:52:30 GMT
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That jig does seem to have worked like a charm indeed  Love the ethos of this build! Surely if the 1275 CG13 only makes 75bhp, its still much better than the A series? Lighter, more efficient engine design, and loves to rev as standard anyway! Can't see any downsides personally |
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Mar 26, 2021 22:33:23 GMT
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Hi,
Love the kit you made for everyone.
I think many people are getting it wrong here.
Standard 1275 engine only produced 65bhp when it was new. Midgets are getting old.
So most likely, you will need rebuild and still have 4 speed gearbox.
With your kit, you are having easy 75bhp as standard with injection.
I know with bike carbs, it will rev quiker with your aftermarket peformance exhuast manifold.
I think you will see over 80bhp with standard cams.
How much will that cost if you decided to use A-series?
I was going to build 16v head A-series with 73.5 pistons with South African 1100 crankshaft(similar stroke to 970) and add 5 speed gearbox for a good measure. I added up all of the cost and it was £8.5k just for an engine and a gearbox. Can you imagine how many time you have to rebuild? Perhaps every 3 years if you are lucky.
So I looked into Suzuki Swift GTi. It come with 105ps as standard and 5 speed gearbox. My friend offered me for £150 including ECU, wiring harness and everthing you need for a conversion.
My engine has now R1 carbs, Group A camshaft and P&P head(increased CR) and RC40 1.75" exhaust.
It is now good for 140bhp for very little money.
I think J engines are good for 150k miles before you needs to rebuild.
So once you finsh building this car, you can enjoy another 40 years!
Cheers
Atchi
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Building roof chopped, screen raked '68 Mini with G13B 1.3 16v Gti engine with LSD, Yamaha R1 carbs. As well as mk1 Suzuki Swift Gti AWD with a turbo.
Drives PHEV Outlander but wishing my mk1 Swift Gti or mk2 CRX Vt were still with me!
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miniswift Thank you Atchi, you've summed up the ethos behind the build really well. Progress has been slow and steady. The gearbox bellhousing has now also been relieved to clear the starter motor crank position sensor, now mounted in a new billet bracket which will prevent any risk of the sensor moving again.   The gear selector assembly is also back together with the two shafts MIG welded together to delete the UJ. It get it all working smoothly several hours were spent on the press getting everything straight again - inevitable when welding that there would be some distortion. The bores were also cleaned up with some 120g on a long stick in the drill. It was well worth it though with a really nice positive gear change with a short throw.  The gearbox was then refitting to the engine with the clutch assembled so the travel could be assessed. I used a length of M5 studding to control the clutch arm position and measured 30mm of travel necessary to move from the bearing lightly touching to the clutch disengaging with the output shaft turning feely by hand. The only issue is the arm being very close to the casting at this point leaving no further adjustment should it be needed - there is the risk that the clutch may be slightly dragging still. To fix this I can either put a spacer behind the release bearing or shim out the pivot bolt.   I am still flip flopping on clutch actuation but a Mk1 Escort cable looks to be the right length. To convert to a cable I will need to extend the end of the clutch pedal as the current total travel is only 20mm. Other than finishing the clutch I am only waiting on a prop shaft before the engine can be refitted. As a side project I have revisited the inlet manifold. As said before, it is a perfectly function home made special made from gas pipe. The problem is the port matching and 45 degree bends are incredibly sub-optimal for flow. It is also a pain to fit because the round pipes does not give enough clearance to do up the central nuts more than 1/16" at a time! Bad thoughts of filling the ports with JB Weld and then reshaping made it further that they should have before I decided to take more drastic action... Enter the 3D printer - nothing special, a cheap but well regarded Chinese Ender 3 v2. I am really impressed with this machine - assembly was straight forward with actually good instructions and very little setup was required to get good prints  Starting small with a 50% scale test to check everything worked  Followed by a full scale print  These are just PLA prototypes - only good to ~60C so not functional yet. The plan is to upgrade the printer so I can print the actual parts in carbon reinforced Nylon. I will also be upgrading the mounts to flanged style ones to better support the carbs and eliminate the problem of creep that I think could be an issue with clamping a hose style connector onto a print. More on this as and when - the focus is on getting back on the road ASAP Thanks for looking James
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