NickJ's Lada Niva TwinCam

[NickJ]

With the workshop staff still on summer break I spread Lada/Fiat bits across the main workbench and had a leisurely measure up of vitals

I then spied a lonely looking mill in the corner and gave her something to do

End result was 2.1mm off thickness taken off the 8mm flange to get it flat, was a pig to hold down without warping too much, I now fear it may flex and wobble in use, but hopefully will seal better/easier than it was before.

The engine side is thankfully not as bad as it would be a pain to hold down but if I can work it out it might get similar treatment.

 

[NickJ]

I had plans to get the Niva ready months ago, but work had different plans, I finally dropped the engine off to have all the vitals tickled, while its not going to be a 'performance' build, it will be a darn sight better than previous, i'm hoping to at least have compression back!

With Otago rally on this weekend, I was hoping to use the drive there and back to run the engine in, sadly the weather has been absolutely terrible and in my crampt shed with not enough light, achievement has been low.

Utilising the parts cleaner obtained off Bart, I've sparkled up the underside bits, ultimately, only the wof man will ever see it...

Threw on a lick of speed enhancing red

Multifunction 2105 workbench:

Forgot how much I enjoy assembling engines, checking, cleaning measuring and torquing, no pics cos its dark, but the block is back together and awaiting a break in the clouds to lift it all into place

I've also sealed up a 5 speed box I rebuilt ages ago, 4 just wasn't enough!

Sitting out the rain I got onto the computer and drew up a head gasket, my sources have all dried up on standard thicknesses so i'll run a thick one until I get one waterjet cut from copper to give a hoon, hopefully it works......

 

[NickJ]

Much to talk about...

First of all, 

#CleansheetVTNZ #Levelimposibleclocked

 

Time to set my mind onto more interesting things, hooked up the wideband to the Niva and had a horrible surprise, all nice at idle and up to 50kmh, but then open up the secondaries and she's rich as, so rich no amount of tweaking and miniature jets could alter, I gave the single carb a full half day of messing about but in the end ditched it for the dellortos, even though these are rich, the results were far more consistent and changes to mixture followed changes I made.

With the twins on it was time for some serious thinking, driving around with the wideband on the dash wasn't really the easiest thing to do so I sat down last night with a beer and bashed the keyboard to get python to read throttle position and mixture via arduino, all thats needed then is a tps on the carb, PAP wanted $40 but i'm too cheap for that kind of extravagance, headed down to jaycar and grabbed a $3 10k potentiometer and aluminium knob for $4, mix that with a bit of scrap ali sheet and boom, tps! (well not quite, still had to hack a slot for the shaft to engage in, man I wish I had a mill!)

All that set up I dumped the laptop in the passengers seat and had a play

Worked out far better than I imagined, managed to tune Idle much quicker than listening, by simply looking at the rev counter and O2 reading, awesome!

Pre-drive calibrating of the tps found this wee fella:

The 3 equal peaks are me pushing the throttle pedal, the larger peak is holding full throttle on the carbs, few free ponies if I sort the linkages better!

With that in mind, I went for a drive and things got tricky...

Blue line is O2, red tps, scale is kinda random, but ~500 = good for mixture, tps runs 180->1024 and ignore the green, thats there for when I get engine speed mixed in, but so far its floating along for fun. Oh and graph reads right to left.

At cruise and idle mixture is about right, average acceleration (pulling away from lights etc) is lean as, while planting foot runs mega rich(after a brief lean out), my conclusion is the idle jets are a bit small, and needs a size or two up there, and the mains need to be dropped a similar amount with a little more on the pump jets to see about the lean as the pedal hits the floor.

Fun times, but man I wish I could just go full EFI without having to cert the darn thing!

Discussion about carb tuning tips please:

 

 

[NickJ]

Because Anton failed my last submission i've tinkered with the code:

Labels, scale and grid, well kinda

Bench test only, cos its dark out.

Speaking last night with a knowledgeable carb tuner, my initial analysis is off, word is idles sound fine, but mains are lean and the air correctors could be opened up to prevent flooding at high revs, I have a lead for some jets to try and failing that there may be a set of jet drills near by too.

I also brought a LM2917 IC, this has a fancy trick of turning frequency to a linear voltage, ie give it a signal from the points and it will output 0-5V for the arduino, i've put together a small circuit on veroboard, but just need to bench test it along with an isolation circuit (optocouplers) so i don't risk getting the points running via my laptop!

[NickJ]

Been a few months since I really updated progress, so

Got really pissed off with chasing issues in the carbs, that I traced to a vacuum leak, fixed that for a quick win, got the LM2917 running and lined up all data points on the one plot, this ended up to be very useful and with that and a set of micro drills, I soldered and drilled my way to a decent mixture, eventually settling on 0.5 idles, 1.20 mains and 2.0 air correctors, pretty much the same as where I started! there are a few more gremlins in there, I have reason to believe the pump jets are a tad rich, but economy is acceptable and that was really all I was after!

A couple of days later the stalling at idle came back, notably at the gate into work, at the same time one of the older staff members who happened to be a capable mechanic heard it splutter and came over full barry spec commenting the Russians swapped Ladas for butter, oh and plugs are too cold. Sure enough, purchased up a grade and stalling be gone! 

That would have been the start of winter, with a running Lada, I dug into Niva orientated activities:

Drove up mountains to frolic in the snow:

Then spring came, so drove up mountains to fill the freezer:

Life was good, then on the way home  one evening there was a loud bang, followed by nothing but concern, figuring I wasn't in the ditch I carried on carefully, arriving home I looked closer:

Hmm, so a few phone calls to my parts man and spun a few spanners on the magic floating Lada

Couldn't resist a flick of paint while there

Reverse spanner spin

All in time for a late night run to the mountains for one last weekend

I was promised spring shred, but woke to snow, Niva looked happier than Vladimir necking vodka

Returning home the steering box made a few bad noises, being that the wof was a few weeks from dead it was back to the axle stands but this time the front end up high, I then got way too motivated and pulled the steering system out, along with some worn ball joints...... Poor thing is now destined to sit on the stands til after christmas as I just don't have time right now to really do the work right!

After all this time and effort to get the Dellortos running correctly i'm 90% convinced they are coming out, I have an efi option on the cards thats just too good to refuse.

[NickJ]

99% sure the dellortos are now heading for the shelf, had some younger, more attractive twins dropped off last week

Nissan GTiR itbs, complete with all the bits and loom required, i've also got the speeduino assembled and running on the workbench to organise the electrons, small issues still around injector choice, engine sensor locations, fuel pump and regulator, but all in all the pieces are there.

Biggest pain is it will require a re-cert, i've been through it all once before and comfortable it will be able to pass, but am left considering if I should do any other mods while there! At least with christmas running up fast I just don't have the time so will worry about that next year!

[NickJ]

Got the Speeduino running and sat down to give it a bench test, hooked up the tps, fed a simulated crank sensor in and scoped the outputs.

Pretty darned stoked to have it this far, found I had installed a few parts wrong during initial assembly which caused some searching, I even contemplated ordering a megasquirt if the fault was too hard to find, but thanks to open source and having all the circuit info available, a reversed capacitor was to blame and all is now working as intended. 

Drew up a concept for the manifold, while I can't quite make it as I initially though, it will still work with some extra manual labour, the idea being a single piece aluminium adapter plate won't require welding (I just don't have that much time anymore!) bit of manual machining needed and then sitting down with a die grinder for the final match up shouold do the trick. This will also keep the final package tidy in the engine bay, currently the manifold I made to snake around the distributor and dellortos is as large as the head and looks a little out of proportion (say the guy putting all this effort into a Niva)

Printed out fullsize for a quick check, good thing as I had the itb sketch upside down! i'll fix that and then look to getting the blank cut out.

also need to give them a good clean, a little grimy as well as the token Al swarf from being under a workbench the last few years!

[NickJ]

As normal in life, just as you commit to a project priorities change, sadly the EFI conversion is now on the slow boat as the house needs some funds, i've had the car long enough, whats a few more years!

Having another think about the mixture, even though the wideband says its running lean at cruise, fuel consumption suggested otherwise, most likely cause, the brake booster, so that was disconnected and I went for a drive.

80kph with vacuum hose connected

And with the hose disconnected/blocked off

Blue=tps
Green = wideband
Red should be engine speed, but the analogue-digital converter wasn't playing nice so it just floated along with mixture.

While there are a few months between the two comparisons, i'm confident this is worth chasing as there was no change in the brake feel, best be adding a brake booster to the shopping list! 

Another interesting point is the mixture plot has less fluctuations, interestings.... I'm also sitting right where I was told i'd end up, having to choose between cruise economy and wot performance, regardless I will fiddle with the jets and see what happens.

I've also acquired some rear callipers from Bart, plan to graft some front disks onto the rear shafts and finally get rid of the constant wof issues drums are so keen to provide.

 

 

[NickJ]

Some good learning today, have been bracketing jet size around what is currently working and found going from 110 main to 100 is like falling off a cliff, having the datalogger hooked up allowed me to see when the idle/primary system moves into the main jets, everything would drive fine up to 40% throttle, hit 45% and nothing but lean, this confirmed the primary circuit is close if not a touch rich and I can focus a bit more on fine tuning the mains. This also showed up a another gem, the lean hole that i've had forever between the two circuits is looking most likely to do with the emulsion tubes, I have increasing confidence now to solder up some ports in the emulsion tubes to see what happens.

Lada themed curtesy image:

 

[NickJ]

Pulled up my suspenders, slid on some spectacles and fired up the soldering iron, the day has arrived to attack the emulsion tubes!

From the previous post, suspicions of the emulsion tubes not being right was strengthened, spending the day pondering methods to attack I settled on the 4 large holes at the top, from my understanding, the jet at the bottom controls fuel flow to the venturi, via the emulsion tube, which mixes air into the fuel assisting atomisation, this air mix is governed by the air corrector and the series of smaller passages along the length of the tube. roughly speaking, the holes at the top control mix at idle, the holes lower down, WOT. Having already messed with the air corrector diameter and unable find a combination that gave good mixture throughout, I was always left with a gaping hole around 3500rpm, so, dead spot around 40% throttle and 4 large holes around one third of the emulsion tube, reasonable place to start!

Now, one would ask, why not just buy another set? well first of all, i'm cheap, a set of four to try would be a good chunk of efi money, second, i'm a sucker for learning and thirdly, the only difference between the 4 available styles is the body diameter of which I can't find solid data on what this actually changes.

So, remove said items:

Air corrector at the top, emulsion tube center, main jet bottom.

Fill 2 of the 4 upper radial holes with solder

and leave to dry

Being a Friday night, I felt a quick drive was needed, so not expecting much I casually drove out to the open road and wow what a difference! the chasm is now a friendly ditch, I really should have hooked up the data logger as mixture stayed within acceptable limits for the first time throughout the rev range, more testing needed but a step forward in battling against the 50 fudges that constitute mechanical carburettors. 

 

 

PS, this is in no way an endorsement of twin carbs, EFI is king!

 

[NickJ]

Development has slowed, but the Niva is driving well, even completing a few road trips. Fuel economy was a tad crap, but performance has been satisfactory, I had the wideband hooked up the majority of the trips and the results are pleasing, while still a bit rich, it never leaned out under full power, for now that will have to do!

I recently returned from Jackson Bay via the west coast, here's a few pics, such a nice place to travel through.

On the way I called in to catch up with a good mate, TCGC.

Found some long straight (bumpy) roads

Beaches

Surf was a bit lousy

On the engine fixing side I had a fellow OSer 3d print some intake trumpets, they look the part, I just need to tidy them up a tad, 

After 2000km of worry-free motoring something had to give, most likely picked up some British virus near Timaru and now sports a large oil leak from around the sump, i'll have to explore further, so for now she's having a rest as I focus on work.

[NickJ]

Had a generally good run out of the Niva recently, not that it really does much work, spends most of its life in the shed and then gets rolled out for weekends away.

Went for a drive down south Canterbury way and found another Niva hiding away in daily use.

Also had a look around a few of the high country valleys over winter:

After this trip on rough river stones the steering idler once again slogged out, upon measure up I found the shaft is slightly undersize, that explains years of rapidly wearing out bushes! A quick call to a supplier and I had some nylatron through the lathe with much less clearance.

And of course something big had to happen, on checking the car over before a trip I found a missing washer and screw in the intake, the screw was caught in the carb throat, the washer no where to be seen.....

After trying the obvious, I made the call to strip the head in expectation of a gouged bore, but no, nothing seen but a few divots in the head and piston, it appears the washer made it to freedom via a brief beating in #4, once again, the gods seem to smile on me!

Moving forward the Niva will keep hanging out in the shed with occasional weekends out, but come christmas improvements will slow......

This weekend I picked up part A of my legit black plated new project (cheers Greg!) while a few OS'ers know about my excitement, i'll wait till I pick it up to start the build thread, for now here's a teaser:

And for those that don't identify as a drivetrain Barry....

 

[NickJ]

And nearly a year later......

Oil leak finally got to the point of Greenpeace protestors chaining themselves around the car.....

Finally got around to setting up the electric winch I brought off @HKM400 ages ago, wish I had one of these since day one, engine removal was a breeze!

Turned out the diff mount had been rubbing on the sump leaving quite a hole, once again the lada gods smiled as it also made a reasonable job of blocking the hole.

With the engine out I modified the sump to have more clearance and TIGed up the hole in time for a trip to the hills.

Always fun taking the Niva up into the snow

Also surprising that i've put chains on it twice this year, that doubles the number of times its had chains in my ownership!

 

[NickJ]

Been having hot start issues with the engine, worst of all being random which hampered troubleshooting.

I also didn't bother refitting the fan when the engine was out as i've often wondered how much effect it gives without a cowl and so far back, unfortunately it draws sufficient air to keep the engine cool at idle so leaving the car running for short stops was not an option. (Must re-fit...)

Keeping to my usual mantra of when it seems like the carburettors are playing up its the ignition I started swapping out bits that I could.

Given the brand of the coil I was left unsure of the results, resistance to start hot was still present, or do I have two faulty coils?

This game carried on with all major components including stripping and checking the distributor to no avail.

Just maybe it is fuel this time? Fitting the wideband straight away gave the answer, massively lean at idle..... Quick spray of butane found the leak point and left me quite impressed that the drivability was not noticeably worse. Remove carbs, clean, check refit + new gasket.

Aaaaaaaaand its back to life, solid idle just on the rich side of 14.7 to aid starting.

Now on summer break I have plans for some trips away, one task on my list that remains unchecked is to drop the steering box and inspect. This is where the personality of the Niva starts to come out..

 

I have been unenthusiastic about this task due to all the nasty hidden bolts and knocking off ball joints etc, took a solid 4 hours to get the box out along with almost everything else on that side of the motor, as painful as it is to remove half the engine bay to access one part, i'm quite glad its not modern Japanese and I can fit my hands and spanners where they need to be!

Once again inspection found trouble, grittiness in the box was due to pitting/chipping in the gears, quite likely from rough treatment prior to purchasing joint pullers.....

Not wanting to put that box back in, I pulled out a spare, being of unknown quality I decided to strip it down first, what a fun mistake that was!

Only seal I really cared about was the lower one, carefully hidden under the pitman arm, initially I hooked up my 2 jaw puller but it just didn't like the shape falling off with only moderate load, at 17:20 I had enough and headed down to Repco and brought a pitman arm puller, as they closed for the day, even with greased up threads I couldn't budge the darn thing, stern words were muttered and I left it for the night retreating inside for tea.

After a second prolonged struggle using various combinations of tools, percussion and  finally the purchase of a gas torch, the arm relented, clean-inspect-reassemble resulted in one new condition steering box.

Lovely clean looking steering box too, and possibly the most expensive maintenance item for some time!

Only a few short hours will have the Niva back on the road...... except for NY hangover, just lifting tools is bit of a challenge right now, hence i'm writing about fixing rather than actual fixing!

 

[NickJ]

Earlier this year I went for a 4wd mission to scope new hunting areas and came to the realisation that I was choosing spots based on where the Niva could go and not where I wanted to go, the big barrier on the east coast is rivers, and the fiat motor hates water!

We managed 15min up this valley before being forced to cross the river, issue with the twin cam is the spark plugs are located in the valley between the two cams, any splash of water is directed here which promptly kills the engine, normally mid-current.

We turned around and headed home, on the way back I was pondering methods to prevent water but nothing was simple or failsafe.

What I needed was a snorkel, diesel, raised breathers, longer wheelbase and bigger wheels........

With this in mind I set to work....

The snorkel was easy, pretty much bolt on

Diesel pump to fiat twincam was tricky, but with a big enough hammer it went into place

Bigger wheels needed clearance, overload springs were installed

This all took quite some time, and the result somewhat best enjoyed with a cup of tea in hand

Unfortunately i've replaced the Niva with a more suitable vehicle for my current needs. I have access to a garage not too far from home that once lockdown is over it will be tucked into, My mind says I should sell it and move on, but I can't bear the thought just yet of parting, its been a great toy over the years and really is a hoot to drive, sadly I just don't have the space for so many cars!

Before parking up, I plan to carve out some rust to be sure there is no deterioration, parked up in WOF condition is the plan, ready to hoon should the urge arise.

[NickJ]

The Niva's replacement has settled in and proven it's worth, so unfortunately the rego is very much on hold and not looking like revival any time soon.

The financial roller coaster of 2020 has had my finger hanging over the sell button, so far i've managed to hold off and I really hope thats all over with stability actually on the horizon.

Lockdown feels like so long ago, like everyone else, with time on my hands I got stuck in with general maintenance and cutting out some rot, quite glad I got in when I did!

This location behind the front wheels is a standard trap, there is a panel to flush the gunk out but, yeah, rust  

Over the winter the Defender was needed for another mission so with the aid of WOF extensions, I threw a month rego on and took the Niva for a spin up to work

Was bloody good fun to have it on a skifield access road again and quite a fitting last trip. Right now there is no reason that it shouldn't pass a WOF so i'm quite happy to be putting it to bed in this condition, sleep well wee Niva, you shall hoon again!

[NickJ]

4 years later..... welcome home old friend

Those years in a shed haven't been kind, I have some work to do.