Welcome back to my garage. I’m happy to report that over the past month a whole lot has happened and progress with Project Z is on a roll. You might be looking at this photo and thinking I’ve gone mad, but don’t worry – the G-nose will be back soon enough. While the car has no motor in it we’ve decided to take the opportunity to give the engine bay a proper tidy up.
First the front body panels had to be removed so that we could start prepping the engine bay to be cleaned up, repainted and then eventually rewired. It felt weird seeing the freshly painted G-nose and fenders coming off, and even weirder seeing the Z in this half zombified-looking state.
I’ve been lucky enough to have the help of some awesome friends who have been helping me on the weekends and even on weeknights too. I can’t begin to thank them enough for their help.
I’m not a mechanic and I didn’t grown up around cars at all, but over the last few years I’ve really tried my best to throw myself into modifying my own projects so that I can really understand everything from a hands-on point of view. It’s been stressful at times and I’ve learnt that patience is key, but I absolutely love it. I can’t say that I particularly love sanding that much though!
After my friend Michelle and I prepped the bay for its eventual first coat of primer, it was time to remove a whole lot of ugly bits protruding from the engine bay…
… of which there turned out to be quite a few! Since we had previously removed the fuel injection system, there were a lot of unused brackets as well as what I can only describe as industrial strength twistie-ties to hold the now mostly-useless looms in place.
There were now a lot of redundant holes throughout the engine bay so these were closed up thanks to my friend Marcus, who conveniently happens to know his way around a welder pretty well.
This process is so fun to take photos of, but I struggle not to look at the light! It’s like when someone yells: “Look, boobs!” You just can’t not look, am I wrong?
It’s still far from completion but the engine bay is going to look amazing once it’s done, and it’ll be such a huge improvement in comparison to before which I’m really excited about. But the burning question here is – what’s going to be sitting in it? I left you all with a bit of a cliff-hanger recently with what was going to happen the original L28 motor and whether or not it would be worth rebuilding.
Even I wasn’t sure what was going to happen at that stage, and I had some interesting suggestions from people about possible options for different engine swaps that I actually did consider.
But I really had my heart set on retaining the SOHC L28 straight-six motor. I wanted to keep the engine set up period-correct as well as being nice to drive on the street but still capable on the track. Plus, to be honest, it’s hard to beat the sound of a worked L-series motor sucking down air through triple sidedrafts. The motor will be staying 2.8-litre, but will be a much angrier beast once it’s all back together. So last month we pulled it out to see if we could figure out why one of the cylinders was so low on compression.
From what we could see there were no problems with the valve clearances, which could have been the cause. So then we removed the head to take a closer look.
The previous owner had been told when he bought the car that it was running flat-top pistons, though he was suspicious that this was not the case. We discovered his suspicions were true when we removed the head and saw the dished pistons in there. Though this obviously had no bearing on the dropped compression of one cylinder, it did suggest that the motor’s compression ratio was going to be super low.
A quick CC test confirmed that the L28 was currently running a very low compression ratio of 8.2:1. Looks like a set of new flat-top pistons will be on the cards!
Next we took the head over to Jason at Cylinder Head Supplies so that he could take a better look and see if he could diagnose the problem.
It didn’t look too pretty, but again there was nothing wrong enough with the valves themselves to cause such a dramatic drop in compression.
Further inspection showed that the N42 cylinder head hadn’t been cooked either, so it was still dead straight…
… and after removing the valves we discovered that at some stage it had been nicely ported and polished. This was something we were planning on doing anyway, so at least this was a good find.
But after fully examining the head and finding no abnormalities, we still hadn’t solved the mystery of why the fifth cylinder was down on compression.
With the motor on a stand we removed the sump and began to drop the pistons, as our next thought was that the issue might lie with the piston rings.
The pistons, although no good for a high compression rebuild, looked really nice.
Sure enough, when piston number five was pulled out, the ring came out in two pieces.
Jason then gave the bores a hone to try and clean them up…
… this however, revealed a score in the cylinder wall from the broken ring – too deep for a hone to fix. It will need a full rebore, which considering the old pistons will be ditched anyway, wasn’t the end of the world. This should see the compression ratio raised to around 9.8:1.
Although having the cylinders rebored will cost a bit of extra cash, I think it’ll be worth it to be able to give the original motor a new and improved lease on life. I’ve become attached to the idea of keeping Project Z true to its heritage, and after much consideration I’ve come to the conclusion that building a motor that’s comfortable for the street and the track is what appeals to me the most. Although the outcome won’t see any extreme power figures, the rebuilt L28 should make the car quite quick extremely fun to drive, and I really want to enjoy driving the Z around town, on road trips throughout New Zealand, and to the track and back. Staying with the classic period correct theme and keeping the soul of Project Z intact definitely feels right, and with a set of new 1mm oversized flat-top pistons on their way from the States as I write this, hopefully by next month the motor should be back together!
Good to see that your keeping it with the stock engine. Thats what I did with mine. Here is something you can come to expect with a high compression engine, and the webers.
Lovely..... I just can't get enough of the old Datsun Z's. You've got me browsing ads for them now, shame they're far pricer in the UK!
judging base on the camshaft, it running on some high degree profile, you really need a flat top piston with valve relief to squeeze the power up, make sure your valve spring up for that task, wiseco have those piston.. if not mistaken
I have a spare L28 in Los Angeles if you want to pay for freight. I don't want anything for it. you can email me at brian at european auto source dot com.
One day l'll live in NZ or Au, and marry a girl into cars like you do!!! http://www.youtube.com/watch?v=-mg4t85qDUw
Hey Taryn, check out Otomoto.com.au (Australian agent) for Kameari products for L-series under Atmo tuning parts. They're not cheap but high quality. Their range of tuned length headers look amazing! , valve springs, chain tensioners, sprockets, stroker kits, pistons etc.
Kameari twin idler gear kit for Nissan L-series engine.
"Twin idler gear kit to replace timing chain tensioner in L16, L18, L20, L24, L26 and L28 engines. Sutiable for up to 13,000rpm" yum
Great article Taryn. I can't wait to hear this thing start up when it's back up and running how it should be :)
Great to see some progress! Great inspiration....
Stewart Wilkins Racing in Sydney makes a great set of headers, tuned length just like the Jap race cars. He also has plenty of specialist parts to get some real decent performance (he was the main race car mechanic for the African Safari Rallys, they used L28s)
CAMSHARFT!!! A real key in unlocking power. And IF you can find a P90 head (normally off a L28 turbo engine, or the L28 Patrol) and get it worked, you cows be on your way to 160kW at the wheels...
For moar go... 3.1 lt stroker kit (using a Patrol Diesel Crank)... but I'm giving away too many secrets now :)
will you drifting it ??looks awesome (remember the final battle on fast and furios tokyo drift use that damn car)
good luck with the rest... :D
Keep it with the l28!!! How can you go wrong with a triple carbs?!?! That is the sound of pure raw sex!
Everytime I see an S30 being built I can't help but get The Wangan Midnight soundtrack out of my head.
Nice article there Taryn this project is nectar! Glad your sticking to the L28. The allure of the blue light will only last until you get 'arc eye' (Basically sunburnt eye balls) and wake up at two in the morning feeling as though someone has poured sand in your eyes. Trust me its not nice nor good for ya haha. Best of luck with the rest of your build, awesome car.
Sounds like what happened with my MR2's engine back in the day. The bore really is your best option. Should be fun! You have one of the more interesting builds on speedhunters in my opinion.
Glad to see you're going with a carbed L. There really is nothing better sounding than triple sidedrafts.
Taryn. Good to hear you're going to stick with the engine and go the sidedraft route! Looking forward to how things work out for you. Once you understand the basics behind tuning it becomes second nature. Going to be making a couple sets of hot-rod-style brazed fuel hardline setups for triple webers, let me know if you want one! Now lets get some of that 94 NZ octane to California! My own triple weber project, not the same car but along the same principles. http://www.bmw2002faq.com/topic/116731-m20-triple-weber-build-x2/
I think you should have added a lil more compression. More like 10.5.1 since your staying na. But on the other hand I love your ride!
Rebuild it with a set of the carby style fuel injected throttle bodies, keep the nice intake noise without the hassle of mucking around with carby jetting when you want to tune it.
Also can't wait to see the end of the build. Needs video of triple Webers sucking down that o2! Even just a recording of the sound is fine by me hehe
@Flauski me too! :)
@TheRobotCow That's the plan! Can't wait!
@Neogeo64 best movie ever for the car i think :)
@Johnny_Bravo Thank-you! My husband got that once, I felt so sorry for him! Sounds painful!
@ClaytonPayton This man speaks the truth. Picked up a box of 100 for 5 or 10 bucks at harbor frieght and its been paying dividends.
@AceAndrew2 Yep we have 91, 95 and 98 Octane all available at the pump in NZ
@Jamie20 u r gay
High comp engines with that head and flat pistons are sensitive to knock. If she were to go any higher comp the chambers will need to be redone for better quench and flame travel or look into getting a high quench head like the MN47. Luckily I think they get 94 octane at the pump down there in NZ so she might be able to run a higher advance and not worry as much about detonation like we do back in California with our weak 91 octane.
Heres some good info on which head might work best for her setup.
@2bAUS This is a great idea. They make throttle bodies that look like webers. Would be awesome. Then megasquirt!
@koko san I was thinking the same as the body of the car. Keep it simple and classic. What do you think?
@Taryn Croucher After experience and speaking with a lot of local racers about this engine, the key is to balance balance balance! The crank balance is crucial and should be within the tightest possible increments. It is also a better idea to update the crappy front pulley on the front of the crank shaft. A lot of guys here in NZ use modified BMW ones which have large portion of rubber sandwiched between two plates (in order to severely reduce vibration.
Even better is to balance the rotating assembly (pistons, rods, crank, front pulley, flywheel/clutch.)
Vibration/balance issues on these engines lunch bearings. Guess it depends on how far you want to go but if your going to the effort of a full rebuild / triple carbs then it can't hurt to be safe rather than sorry.
@Taryn Croucher Awesome! I can't wait to see the next update on your Z!
@Oompa Lucky lucky...... better than the 91 swill we get here in CA.
@Taryn Croucher Simple and classic is always good, another option could be that gold color it already has. Anyway with all those metal bits gone it will look very tidy.