Weekend Automotive Fun

"BoulderZ" (BoulderZ) 05/05/2014 at 13:47 • Filed to: None

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I missed my favorite car show of the year on Sunday. I wasn't going to enter, as I won the Import category last year, but I really did want to attend and see this year's entries. I also missed the snow-delayed Tax Day Decompression meet and drive of the area Datsun enthusiasts. And I didn't get to see any of the Laguna Seca coverage. So, it should have been a terrible weekend, gearhead-wise.

But it wasn't. I have been trying since July of last year to get enough time to fix the manifold gasket on my Z. I had not checked the torque on the header studs-plus-nuts before a track day, and by the time I figured out they were loose, the gasket was done on top of the #6 exhaust outlet. Every time I could get time to work on it, another car would have a must-do repair, or I'd get sent out of town for work, or it would rain/snow/freeze when I needed to do some of the job outside. On Sunday, I finally won.

I got the header and heat shield detached and sufficiently cleared to get at the head under the intake. A new less-tapered 8x1.25 tap and some narrow cleaning brushes let me get the threads back in good shape, and every one of the 11 studs is now brand new. I'm not totally finished. I need a new header-midpipe gasket, which I'll get over lunch today. I need to get 8 more of the nuts on before final torque, and there are some intake assemblies to hook up, but it's all minor re-assembly stuff that I can do in a few hours. The worst part is done. This guy:

...is finally back in place with a new gasket. Which means I can soon hit the track again, just in time for time trials and club days in this guy:

BiTurbo228 - Dr Frankenstein of Spitfires > BoulderZ 05/06/2014 at 02:47

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Mmm 6-1 header.

I've been trying to weigh up whether to get a 6-2-1 or a 6-3-1 header for my Spitfire 6. You can get both of them, and I assume they both fit alright in the chassis. The 6-3-1 is £200 more expensive though...

BoulderZ > BiTurbo228 - Dr Frankenstein of Spitfires 05/06/2014 at 10:48

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I don't know the Spitfire mechanicals in any detail, but it sure looks like a lot of ink has been spilled on the topic. Straight 6's usually afford a decent advantage in room to work on headers. Mine is only a pain because the L28 has the intake and exhaust on the same side. So installing the studs, then the washers and nuts is all done under the intake manifold, with a flexible worklight and a mirror to see where your hands are going.

BiTurbo228 - Dr Frankenstein of Spitfires > BoulderZ 05/06/2014 at 10:56

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Yeah, mine's a reverse flow head as well so less space to work. Still plenty though thanks to the clamshell bonnet.

I also wonder what the weight difference will be between the two, as swapping the Triumph I6 in place of an I4 adds a fair amount of weight to the front. I've done a lot of work sorting that out, and I don't really want to be moving in the opposite direction with this.

BoulderZ > BiTurbo228 - Dr Frankenstein of Spitfires 05/06/2014 at 11:49

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Is the Spitfire I6 an iron block, aluminum head? Didn't know they were reverse flow, too. I like that when I have to work on plugs or change the oil, but it's kind of a pain the rest of the time. I've been surprised at how well some swaps work, in Z's anyway, for weight distribution. The SBC swap that everyone and their brother seems to do ends up with a very nice nearly 50/50 weight distribution. Hopefully yours will have similarly good fortune, without having to get in to a lot of chicanery w/ firewall cutting, battery relocation, mount fabrication, etc.

BiTurbo228 - Dr Frankenstein of Spitfires > BoulderZ 05/06/2014 at 13:54

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Yeah, it's all cast iron. The Spitfire only ever came with an I4, but the GT6 came with a 2.0l I6 based on the Spitfire I4 (mine's a 2.5l based on that 2.0l). It's about 50kg heavier than the I4 so I've got a few alloy bits, lightweight starter and alternator, battery in the boot and a fibreglass bonnet. I'm aiming to keep the stock weight distribution of the Spitfire (56% front), but it's shaping up to be a bit better than that at the moment. If I used the stock Spitfire engine mounts, I could mount it 6 inches back in the chassis and wind up with near-perfect 50/50, but I'm trying to see what can be achieved without that.

I'm surprised that the SBC swap ends up with a better distribution. From what I've read LS engines are a bit heavier than L-series. Only by about 10-15kg, but heavier nonetheless. I suppose the shorter V8 lets you mount it further back in the chassis which makes a big difference.

BoulderZ > BiTurbo228 - Dr Frankenstein of Spitfires 05/06/2014 at 14:33

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That sounds like some really nice custom, upgrade potential on your Spitfire with the GT6 engine.

You have it exactly right with the SBC. Shorter block, farther back equals as-good-as or better weight distrib. Mounts for it are from "Jags That Run", last I heard. I've not done it, myself; I absolutely love the L28 motor in the Z. Speaking of which, just scored the afternoon off. Time to go finish it and drive (fingers crossed...)!

BiTurbo228 - Dr Frankenstein of Spitfires > BoulderZ 05/06/2014 at 14:56

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Sweet :) and good man sticking with the L28. That's my preferred way as well. What sort of other mods have you got on it?

My little Spit should be a bit of a monster by the time it's finished. It'll only end up with 170-180bhp, but roughly the same torque and 750-800kg. Roughly the same power-to-weight as a BMW 1M hopefully :)

BoulderZ > BiTurbo228 - Dr Frankenstein of Spitfires 05/07/2014 at 12:05

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Finished yesterday afternoon, and even drove it! Other mods: Had Web Camshaft regrind my cam to their 94a profile, bored 0.020" over (0.5 mm, I think?), mild head cleanup and three-angle valve job, baffled extra-capacity aluminum oil pan, converted to flattop pistons from the later ZX motor for about 10:1 CR, all urethane suspension bushings, ZX 5 speed (a little stouter), 4 piston vented front disc conversion, rear disc conversion. It's a fun streetable track car, or trackable street car. If I get to swap the kid seat over to it this week, I'd like to drive it to work now that we have some nice weather. Best day-care drop off ride ever, as far as my son is concerned.

Wow, 170-180 bhp in the Spit will be amazing! That car is so light, it'll be a rocket. Will you have to do anything with the wheels/tires/suspension/driveline/brakes to handle the extra power, or are most of those systems stout enough for it already?

BiTurbo228 - Dr Frankenstein of Spitfires > BoulderZ 05/07/2014 at 13:57

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Oh cool :) yours should be pretty hot too. What sort of power are you thinking you're making, and is it on carbs or injection? I remember absolutely loving when my dad would drop me to school in his 914/6. It's something I plan on doing when I have children of my own :)

I'll have 175 or 185 section tyres (the widest I can fit without flares), a gearbox from a TR6, a Quaife LSD in the stock diff and some uprated CV driveshafts and an adapted rotoflex rear suspension, paired to GAZ shocks all round. I've got beefier GT6 brakes as an upgrade, but I'm thinking of slimline alloy 4-pots for the front as I'm not sure they'll be enough.

170bhp would easily overwhelm the stock Spitfire components, so it's just as well I'm going for upgrades :)

BoulderZ > BiTurbo228 - Dr Frankenstein of Spitfires 05/07/2014 at 14:33

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I'm guessing, from others with similar builds, that I'm in about the 170 range, but could be as low as 150, maybe. I blew all my dyno money on tuning the EFI/turbo conversion in my truck, so I haven't gotten to test the Z yet. There was a portable dyno at the car show I missed on Sunday, sadly. That would have been a good, cheap baseline.

In the Z, I'm on EFI. The stock Bosch L-Jetronic system in '78 was super reliable and very easy to work on with nothing more than a multimeter. It's pretty adaptable, short of forced induction, so I stuck with it. If I ever re-do that car for a turbo, I'll switch to Megasquirt. I have SDS in the truck, with a low-boost setup. It's nice, and not having to have a laptop for adjustment is a plus, but it would be much easier to have a proper GUI application for tuning. Fueling is weird here, and very hard on carbs. We're over 1600m altitude (5440'), with passes in the 3500 m (10,000' +) range. An acquaintance with a lovely 70's Lancia has to stop halfway to Estes Park and change the jets in his carbs to keep things running well.

Your mod list sounds like a perfect recipe! I'd like an LSD for the track, but getting one that fits well hasn't worked out yet. I like the 4-pot idea. There's not a lot of downside to brakes that are a little large, but there's a pretty heavy penalty for too little. Are the GAZ shocks adjustable? I went with Tokico blue tubes, but kind of wish I'd used the Illuminas, even though they are a fair bit more money. Hindsight's 20/20 and all that, I suppose.

BiTurbo228 - Dr Frankenstein of Spitfires > BoulderZ 05/07/2014 at 15:25

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Oh wow, I'd never considered having to change jets and that as you go up. The UK's all fairly low down. Where abouts are you?

It's odd with the Datsun L-series because they kept using gross power figures for a long time after most people had switched to net. From what I can work out the L24 was 135bhp (with a year or so at 141), the L26 was 130bhp and the L28 was 151bhp. With the bump in compression and the valve job I could see 170bhp being acheivable, especially if you've got an exhaust as well.

It is the perfect recipe, but I'm paying for it :S still, do it once do it right and all that. That alone might persuade me to wait another month and get alloy 4-pots. The GAZ shocks are 18-point adjustable, but they do both bump and rebound at the same time. Perfect for me, but if you want to really get into suspension tuning probably a little limiting.

Which truck have you got, and what have you done to it?

BoulderZ > BiTurbo228 - Dr Frankenstein of Spitfires 05/07/2014 at 16:20

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I'm in Boulder, CO, US. The conditions here skew the auto fleet. There are ridiculous numbers of Subarus and Audis due to the whole AWD thing, lots of off road opportunity means a lot more SUVs and trucks, and the altitude makes for a lot more forced induction sales.

Yes, Datsun's numbers were notorious. It's pretty much guesswork without a dyno. I'm hoping to have enough of a break from repairs this year to have some money for testing. And some other projects, of course. The truck is an '89 Toyota 2WD, extended cab. I think that's the HiLux on the good side of the pond? Clarkson and crew did a nice job testing one a few years ago. The carb on the stock 22R motor is fairly complex, and I didn't want to rebuild it again, after 10 years, for altitude and emissions testing. One thing lead to another, and I bored it, new pistons and Moly rings, SDS EFI and ignition (distributor delete), T3/T4 turbo (limited at 6 psi for now, good to 12 psi or so), ARP head studs, TrueTrac mechanical LSD, American Racing AR23 wheels, and 29" BF Goodrich All Terrain T/A tires, new rod and main bearings, ARP rod bolts, and a fresh coat of original Cardinal Red.

You'd mentioned remembering getting dropped off at school in your Dad's 914/6. That had to be fun! That modified Spitfire would fill that duty nicely, I'd guess. I had wanted to maybe drive the Z today, but now I'm glad I didn't. We just had a 10 minute minor thunderstorm, with a little bit of pea-sized hail, just to keep it interesting.

BiTurbo228 - Dr Frankenstein of Spitfires > BoulderZ 05/07/2014 at 16:53

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Ah, is that one of the indestructible ones? So it'll be indestructible and turbocharged powerful :) have you been off-roading in it yet?

Surprise hailstorms must make classic ownership a bit nervewracking :S

BoulderZ > BiTurbo228 - Dr Frankenstein of Spitfires 05/08/2014 at 11:02

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Yeah, the 22R will just run, and run, and run, albeit weakly/poorly, pretty much forever. Their big secret to longevity is low power (99 hp when new), 5 main bearings, 2 row timing chain, and some of the sloppiest piston clearance specs ever. The machinist I had doing the bore-out actually called Toyota to verify the clearances, as they're the loosest he'd ever seen. Of course, most of his work is usually sportbikes and circle/dirt track cars, so this was a little odd.

The weather here does influence behavior of classic owners, for sure! You know the location of every underpass with a shoulder, as well as every bank drive through, parking garage, and driveway awning (hotels are good). You also get really good at reading radar imagery and meteorological maps and forecasts. And if all else fails, you get good at noticing when the clouds start to pile up, which way they're going, and automatically thinking of which highways you can use to flee/dodge the storms.