My "L29" build.

jonbills

jonbills

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A little update.
I got it in and running, but the HG was leaking everything everywhere.
Turned out the head bolts were not at correct torque.
My torque wrench had snapped inside as I was installing the flywheel - I got another and thought nothing of it and finished the install.
With the head bolts loose, I can't trust that the main and rod caps are at the right torque.
So the engine is out again for retightening.
Anyway, the exhaust is installed and fits nice and tight.

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Huw

Huw

Club Member
Feel for you Jon, but it's the only way you will get piece of mind and trust the build. Been loving your thread, learnt a lot.:thumbs:
 
jonbills

jonbills

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Thanks. the main and rod caps were a little loose. I Had a look at a few bearings while I was there and they were ok.
So I'm glad I checked.
Still a long time to Z weather so no rush
 
jonbills

jonbills

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At last, it's running again. All 6 cylinders this time.
https://vimeo.com/201545757

It has a new head gasket, 1.0mm rather than 0.8 (Mr Mori advised 1.0 is stronger). So I've inadvertently followed Moriarty & Matt's advice on clearance.

Anything goes wrong now, I'll blame them
 
jonbills

jonbills

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Certainly won't be turning the engine over with a socket on the crank damper any more.
No oil stat - I've heard they're rather a liability. Next weekend I'll fit an oil temp gauge so I know when it's safe.

I also had to put some heat shield back on quick - the exhaust was boiling the fuel in the rear two carbs. Didn't run so well like that.
acf18b06fcb654463aafb4d170910d61.jpg
 
jonbills

jonbills

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Oil temp gauge fitted. Proper job :)
506420b2ec0d9f9ebd2cdc3a6b0a6d3c.jpg


I just need some dry weather without salt on the roads to get it out and sort the jetting.
 
jonbills

jonbills

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OK, just to keep this thread up to date.
On the spur of the moment, I had a go on the rolling road at Mass Racing.
I didn't get a graph, just a peak figure of 210 at the wheels and a suggestion that that's 2/3 of the flywheel power - so very encouraging.

Also confirmed that it's not pinking and that my AFR gauge is reasonably accurate (although read maybe 0.5 below theirs, or perhaps was 0.5 seconds behind - it's hard to tell :unsure:)

And also it showed a big misfire under load above 6k, which I had lots of help on here : http://zclub.net/forum/showthread.php?t=27965

3 things seem to have contributed to the misfire - vacuum leak at the brake servo hose, the coil failing and the spark plug gaps set too big - I'd had them at the 'standard' for 280zx dizzy of 1.1 mm, but now at 0.6mm and, fingers crossed, it's good now.

Next things to address is to improve the mixture in a few places.
It's too rich in the mid range/acceleration phase, so I think I need one step leaner on the emulsion tubes.
Its a tad too lean right at the top end - my AFR is showing around 13.5 at around 7k, and given what I learned about it reading rich I need to go for richer air correctors.
lastly, I hope, It's way too rich on the accelerator pump jets. so smaller ones of them.

For the record, the current carb jet settings are:
45DHLA
39 mm main chokes.
7850.2 idle holder, 52 idle jet.
7772.6 emulsion tube, 160 air correctors, 143 main jet.
45+ pump jets. (45+, since I don't have an accurate measure, I drilled 'em myself http://zclub.net/forum/showthread.php?t=24508).

and the replacements will be:
7772.5 emulsion tubes, 140 air correctors and I'll worry about the pump jets after that.
 
johnymd

johnymd

Club Member
I missed out the plug gap bit on my post. On my 1j I've progressively had to close the gaps up to stop the misfire as I've increased the combustion pressures and meant to mention this. Hope its all sorted now.
 
jonbills

jonbills

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Thanks John, I remember reading that about our 1JZ car. It's great now. I'd like to think I'd have got their on my own, but actually Phil who built the head told me.
 
jonbills

jonbills

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I've been fiddling with jetting a lot, and not really got the mixture right just off idle and in the midrange yet. Just off idle, it's rich ( AFR 10s) but goes lean with a little more throttle.
This week I've made a bit of a breakthrough in understanding how the progression holes work. My progression holes had been drilled and refilled some years ago, and I was looking to return to standard, but I couldn't find the standard progression hole sizes on the internet anywhere.
I sent an email to Eurocarb (dellorto.co.uk) and they very kindly sent me this back:
2caec63c9032ccf7453c627c2dc815d0.jpg

I was a bit dissappointed to find my A hole (tee hee) and B hole are already standard size and my C hole was a tad smaller (0.8mm).
The breakthrough is that I found on sideways-technologies.co.uk a thread that explains that progression holes on the air filter side of the throttle plate add air to the mixture and those on the engine side add fuel.
So making hole C slighty larger has the effect of making it leaner when only hole A is on the engine side and richer when all 3 holes are on the engine side.
So now, with 1.0mm hole C, it's running AFR 12 just off idle and a little less lean as I open the throttle further.
Next step... I need a 1.1mm drill for hole C.
Then maybe crack the midrange. At the moment it's very rich (AFR 10 again) between 2500 and 4k rpm on WOT.
After 4k to about 8k it's perfect at about AFR 12.5.
 
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