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Nana Spec 69' 510

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Ok, next dilemma. Having an issue at low revs under load. For example 35mph in 4th gear. The ignition breaks up and it coughs and splutters. I've cleaned the points and put new plugs in it recently but it doesn't seem to have helped. Thoughts? Condensor? New points? 

Edited by slowlearner

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80% of ignition problems turn out to be carburetor and 80% of carburetor problems turn out to be ignition.


There is no accelerator pump on an SU it relies on the thickness of the dash pot oil to delay the slide moving up. Check they are full. Most use 3-in-1 oil or ATF.

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One issue I had was the aftermarket point spring (arc) was too long, shorting out on the dizzy housing. Only found it by cranking the engine over with the cap off. Didn't do it all the time but when it did, it lit up like the 4th of July. Had to get an oem point (factory spring arc). Just a thought.

Edited by Fetch

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It's been an eventful few days for Nanaspec, heading off to SW Motorsport for a proper tune. And just as well too. It was running like a bag of spanners. Wouldn't idle properly and kept breaking up at low revs.



Stewart and his team are the gurus of tuning carbs on Dattos and despite pretty much everything going wrong, it turned out really well. It ended up costing a lot of money, but the car is literally transformed. I couldn't believe how much nicer it was to drive. He also went looking for the petrol stink in the car, but couldn't find it. Of course, another surprise greeted me when I hoped in. The bottom spring clip had come off the window winder and the window had come off all it's rollers and was sitting in the bottom of the door. I had to drive the car up the mountains to a meeting, so duct tape won the day. 


Today was another adventure...



The first CACA motorkhana in the car with my 16yo daughter driving as well. @Lachlan also came along in his Mazda 323 metro. You can see the in car footage from a few runs in my car above.


I learned a few more things today;


1. It's a bit droney in the car on the freeway at 60mph.

Another muffler should fix this. A special muffler in the shape of a snail. 🤓


2. The speedo is about 12mph to fast at 60mph.

My GPS speedo app on my phone helped me with this.


3. I need to lower the back of the car a little to get rid of the slightly positive camber on the back wheels.

To put this in perspective. Before the khana, the first thing I did was put super skinny tyres on the back. I had 29psi in the front and 45psi in the rear tyres. Usually this would mean instant tail-happy action in any other car. Instead, I had on and off issues with the car plough understeering, starting to transition into oversteer and then lurching back into understeer. My datto guru drove the car after me and had the same experience and confirmed my suspicions. So I'll need to find some shorter springs... or trim a coil off the current ones. I suspect my current springs are slightly too long anyway. I'm not a fan of cutting springs, but it might be an option with these ones.


4. I want a better handbrake setup. 

The umbrella hand (park) brake is terrible for handbrake turns. Apparently one solution is fitting a Datsun A10 Stanza (Violet) handbrake assembly between the seats. My other option is keeping the standard park brake and adding a hydraulic hand brake. I've got to look into into the legalities of that. I think the A10 setup might be better. Either way. I need a better setup, coz leaning forward to grab the handle SUCKS!


5. Broadly speaking, I think the car has enough power as is.

When I say this, it can spin the tyres on dry concrete and even do so in 2nd gear on wet concrete. The chassis is letting me down, but I think it's manageable to improve. 


Overall, I'm pretty happy. The beetle I had before took a LOT of effort to make it work and this car is obviously bags better straight off. I'm also really enjoying driving it. It idles, pulls away gently and goes really well. It's not fast, but it sounds good and it's lots of fun. It's also very forgiving for learner drivers. My daughter stalled and lugged it all over the pits today and it just took it and went. Stew was also very positive about it the other day. He said, "If you put some paint on it, it would be perfect." The reality of that is $10k here and neither I, nor my finance minister (wife) is interested in that. Besides, we'd be afraid of scratching it then.  

Edited by slowlearner
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Been driving the car a LOT recently. The longest trip was across town to collect my upright bass the other day...





I gotta say, it's such a nice thing to drive. Even in peak hour on a hot day (85degF) it just doesn't get hot. The new radiator is sweet. It also turns out that my upright bass fits fine in the front seat.


I also had my Bilstein decals turn up after SIX MONTHS! 




Still gotta put these on. In other news, I got a choke cable from Stewart Wilkins the other day and fitted it to the Hitachis. Coz, it doesn't like starting with no choke now. 

Edited by slowlearner

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Another big arvo on the Datto... (grrr, insta link isn't working)




Like usual I was overthinking the rear springs. But when I got into it, it wasn't so bad. The hardest things to removing the driveshaft bolts. Stew Wilkins gave me a tip about getting it right.


"Cut off half as much as you want to lower it by."


I piled my wife and 2 of the kids in back of the car to try and get a measure for where it should be. Then I looked up some pics online of rally cars resting. For the most part they looked level, where as mine was backside up (floor to side trim; front 285mm; rear 317mm). So I ended up cutting an inch (25mm) out of them. When I got the car back on together, the car looked backside down, but when I measured it I got; 280mm front; 280mm rear. Dead even. So I guess that's a win. 




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Took the car out for a spin last night with my wife. Lot's of windy road and a slow old car = fun. Putting three teenage kids in the back seat on the way made Nana sit pretty low though, lol. 


As you can see, it's sitting a lot more even now.


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Been nearly a month since I last posted and LOTS has happened. I've been offered a new job and taken it, which is great for my whole family. Unfortunately, it also means moving again... that's three times in three years. We have to sort out what to do with our house and I've had to downsize some wood work tools too. Where I'm going we're provided with a really nice house, but I'm going from a 2 car garage to a generous 1 car garage. So yeah, not so much room for junk, although there is some sneaky storage for parts.


In Datsun world, the car has been getting driven 3-4 days a week. Stewart Wilkin's tuning the car was worth every dollar. The twin hitachis (SUs) are very sweet carbs and give lots of down low torque as well as fun shouty noises with your foot flat. 😁


I'm still battling a few issues, but they might have to wait til next year and I have these things to put on the car...

Megasquirt EFI

Race motor

Back mudflaps

Hydraulic handbrake

Proper rear exhaust mount


My turbo guru mate and I are planning a few things like maybe a different cam and a turbo. He has an adjustable nozzle turbo off a 3 litre diesel hilux he thinks is perfect. 

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Trying to sort out a few things before moving. One of them is a baffled rear sump for my l18 race motor. I've been fiddling with the temple Stewart Wilkins gave me a while back. Today I got it almost sorted. I also pulled the Stanza sump off and had a look at the bottom end. Suffice to say I'm very happy. It's obviously been fully balanced. It's also pretty clean.





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Went out to Stewart Wilkins Motorsport. They were kind enough to print out the graph for my dyno tune. I'm a bit scared for my driveshafts with a neck snapping 67hp and 75lb at the wheels! He also gave me a table of all the fuel mixtures which will help come efi time.


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