Dave on dynos, electric parkbrakes and stringing you on Morley's Workshop 436

By: Dave Morley

Presented by

dyno day dyno day

Dyno Dave on the perils of lean mixture. Holden factory engine-tolerance facts. Lexus temp-gauge issues. And much more...



I went to a dyno day last weekend. Run by a car club I’m kind of, sort of, loosely associated with (as in, I’m not a member, but I know a handful of blokes who are). It was staged at a big, flash, spotless, shiny-floor workshop of a major race-prep shop.

Now, I’ll be right up front here: I don’t really like dynos. I don’t like standing anywhere near them, especially when there’s six litres of angry, supercharged mayhem strapped to the rollers. I’ve seen what happens when a clutch or flywheel explodes and, frankly, I don’t want to be anywhere near it. Fortunately, in this case, the day was run by a team of people who understood safety and while there was plenty of space to see what was going on, none of us civilians got to close to the action.

The other thing I’m not mad about when it comes to dynos is the savagery they dish out on a car. I’ve seen too many videos of cars coming off those stupid, single-roller dynos the Americans tend to favour. Likewise, I don’t enjoy the thought of my engine going from full load at redline to zero load when the operator steps off the gas at the end of the run. Ever heard of rod-stretch? It’s enough to give a tappet-head nightmares.


Again, though, the mob we were dealing with on the weekend had all those bases covered. For a start, the dyno is the much safer, double-roller variety which not only reduces massively the chance of the car stepping off, but also ensures the car is always centred on the rollers. And it seemed to me that once the run was done, the dyno decelerated the engine a bit more gradually than simply the equivalent of stomping on the clutch like it was doing a plug-chop.

It was also illustrated to me exactly why you would use a dyno. Okay, we were just there to see who had bragging rights at the next club meeting, and who was going to have to shout the bar for having the most feeble output. But one of my mates stuck his electronically-injected later-model engine (In an Anglia 105E, but you get the idea) on the rollers and cranked out a pretty good figure. Pretty good, but not stellar.

And that’s because the engine didn’t want to rev out to its full 7500rpm. Instead, it started to lean out at about 6500, leading the dyno operator to pull the pin at that point. This is what I’m talking about. Because the operator could see exactly what was going on with mixtures and what-not, he was able to cut the run short to avoid any damage.

So while I was once inclined to do things the old fashioned way using a deserted stretch of road (or, God’s dyno as I like to call it) I have to admit that in the same situation, I’d have revved the car hard in a lean-mixture situation. And maybe damaged something or even blown the thing to smithereens. Thing is, this car has been on the road for a few years now, and this was its first dyno run, so my buddy has been driving it around with it leaning out at the top end for thousands of kliks.

This revelation comes a few weeks after I strapped the RA40 to the dyno for a tune. I wasn’t real happy about it, but now I’m much more comfortable with the thought. And it’ll go back on the rollers when it goes back for the final fiddles on the twin Solex carbys.

For the moment, though, I’ve been having a tweak at home and the results are actually pretty promising. There’s still a small flat spot off idle, but now that I’ve fixed the monster vacuum leak, the thing is much happier. Most recently I’ve wound the mixtures in to roughly where they should be and managed to synchronise the two carbs pretty accurately. And the little orange nugget is fairly flying. Relatively speaking.

Actually, that’s another thing I’ve had to put into perspective. Once upon a time, the 18RG was the last word in Toyota performance; nothing could touch it, especially not in its class at Bathurst. Nowadays, of course, it wouldn’t see which way a hot-hatch went, but it’s still quick to the point of being entertaining. Which in my book, is just on fast enough.


Still the best


I went to the movies a couple of weeks back to see Ford Versus Ferrari. I mean, a great yarn like that needed telling, right? And it wasn’t bad, a few technical errors and a bad case of Fast-And-Furious-gearchanges aside. By coincidence, a few nights later, Grand Prix, starring James Garner was on the telly. And despite being made in 1966, the racing sequences were actually more believable and vastly more accurate. Hollywood eh?



The real red story

engine-plant.jpgWhat looks like an advertisement for OPSM is really an engine plant

It seems a lot of people don’t understand what goes into making an engine or what manufacturers do to control clearances (ie: bearing and piston sizes). Let’s look at piston sizes in a Holden six or V8: These could go from size one to size 25 with one through 16 being `Standard’ and 21 to 25 being 0.005" or 0.006" oversize. From what I can remember there was no size 17-20.

Pistons were placed in a controlled-temperature room for 24 hours before being graded for size. The difference in size was measured in microns and that’s why there were so many variations. If you look at the pan rail of any of these engines you will see that the piston size is stamped adjacent to the bore so that the pistons could be selected and prepared long before insertion on the production line. As far as I can remember there were no oversize rings to go with the 0.005" or 0.006" oversize pistons.

Now for the bearings: If you look at the pan rail again, you will see that there are centre punch marks adjacent to every main bearing cap. One dot equalled a standard bearing, two dots indicated a 0.001" bearing in that location in the block only.

Then, the crankshaft will have coloured daubs of paint next to each main journal indicating standard or 0.001" on that particular journal allowing for the correct bearing to be installed into the main cap. I don’t ever recall seeing 0.010" bearings being installed in the block (as one of your previous respondents claimed). This was to ensure that the assembly process went ahead without too much confusion over selection or placement of that bearing. Remember that one 0.001" bearing takes up 0.0005" of clearance and two shells take up 0.001". All of this extra selection was done to ensure correct oil clearance and tolerance.

As for the crank pins, they were always standard or all re-machined to an undersize. This was done to again avoid confusion on the line. Yes, the old engine plant was getting long in the tooth but even new engines built in new plants with new machines still have select-fit bearings. Rule number-one of engine building: Always build it to spec and build it clean.


JEEZ, WC, if I didn’t know any better, I’d say you’ve been inside your fair share of Holden engines over the years. And in a more-than-cursory way. It’s interesting that you claim all the big-ends were either standard or, if one measured up a bit small, the whole lot were reground to the first undersize. That makes all sorts of sense to me, as it would eliminate somebody putting the wrong bearing in the wrong crankpin on a hazy Monday morning after the Grand Final.

Meantime, I’m off to the shed to check my current red-six build for the punch-marks and stamps indicating piston size. I never knew these marks existed, but clearly, you know what you’re talking about. I guess I’m just like any other workshop dufus: I tend to focus on what I have in front of me, and forget about the history of the thing that could actually be telling me a whole lot more.

And it won’t be just me, WC; that sound you can hear right now is that of UC readers pushing back their chairs and heading out to the shed to take a close look at that old 186 block in the corner.


No gauge, no drive

lexus.jpgGrounded by a dodgy dash

I bought this 1997 Lexus almost two years ago at an auction. I thought it looked lonely and needed some love. It’s just a dream to drive; the smoothest engine I’ve ever owned.  That quad cam goes really well too and still shows the young ones how to boogie. It has just gone past 143,000 kilometres. But just lately the speedo and the tacho have become a little recalcitrant. A quick tap on the dash and needles jump into action and away they go. But last week, the temperature gauge stopped working completely and I’m going nowhere unless that’s operating.

The rest of the car is totally original including the built-in analogue phone and the high-power stereo. It’s an absolutely brilliant car and it gets some lovely comments on its ride and its great condition. And it has always been serviced at a Lexus dealer. 

It’s old but so am I, and I don’t want to trash it because the dash doesn’t work properly, but I can’t find anyone in Queensland who knows how to fix it. The web site bloggers say there are people in America who fix and even guarantee them for life, even the guy at Lexus told me that. Surely there are some bright electrical engineers in Australia who can fix them. Especially if the yanks can.

The normal gauge re-conditioners up here in Queensland want nothing to do with it. So, do you guys know anyone in Australia who does recondition these high-tech gauges. I really love the old girl and I would be very sad if I have to send her off to the wreckers. But you can’t drive a car with no working dash. It does make me wonder how many of these cars are off the road because of this issue.

So now she is sitting quietly beside my little red NA MX5 in the garage at the moment. And if you got to this point, thanks for reading so far.

Nigel Dunlop,

HI NIGEL. I did a quick internet search and found a few joints that claim to be able to fix bung Lexus gauges. They weren’t in Queensland, but they weren’t as far away as the USA, either. Maybe it’d be worth your while to remove the gauge cluster, mail it to one of these specialists and see if they can get you back on the road again.

The other thing that’s a bit hazy is that I’m not sure why your temperature gauge failed. Is it an actual failure of the gauge and/or sender, or is it just a case of the needle not illuminating as it should? Fritzed illumination of Lexus needles is a pretty common thing, especially as the cars age and the printed circuit boards and tricky fluoro displays give up the ghost.

It’d be a crying shame to see a Lexus scrapped for something as simple as a non-working temp gauge, especially when the thing has done less than 150,000km. Let’s not forget, these quad-cam V8 engines are capable of covering better than a million kays, so yours is barely run in.

Actually, when you look at it in those terms, I reckon that even if I couldn’t get it fixed in Australia, I’d be sending the cluster to the US experts. It probably won’t be cheap, but if it saves such a noble car as this with so much life left in it, then I reckon the dollars would be well spent. Your other option, of course, is to find another Lexus at a wrecking yard and pinch the gauges from that. Of course, chances are it’ll have the same set of problems, but it might buy you some time.

The other option – and this is from left field, but hey… – is to fit an aftermarket temperature gauge. I’m not sure whether that’d work, given that the sensor that powers your current gauge also feeds info to the on-board computer, giving the ECU vital info on coolant temperature, allowing the engine to function properly. But maybe there’s a way to add a second temp sender, allowing the original to do its thing while the aftermarket one powers your new temp gauge. A bit of a long shot, I’ll admit.

The high-tech look of the fluoro needles on a Lexus dashboard was a big selling point when these cars were new, but they seem to have become a liability these days. Meantime, I’ll bet the conventional analogue gauges on your Mazda MX-5 work perfectly. Am I right?


String us along

luggage.jpgMorley and Peter seem to agree to disagree on measurements. The real question is does all this luggage fit into the boot of this ‘59 Cadillac? 

Mr Morley, thanks for the larf, but there’s no way the string would be only 628 mm longer going around the Earth.

Try a little experiment: Get a piece of string, then wrap it ‘round your waist, like it was holding up your King Gees. Take note of how many centimetres of string are needed. Now, remove the string and go on a spree of burgers, beer, pizzas, ice cream... whatever you want to scoff down for one month.

Now, get that string out again and wrap it around your belly like you did a month prior and check how many cm you need. How many? Five or six centimetres extra? If you need that much extra string just to go round your expanded waistline, imagine how many extra cm you would need to go around the expanded Earthline.

Peter, Narwee,

HAVE YOU been watching me through my kitchen window or something, Pete? How do you know so much about my dietary habits? This is spooky. Actually, The Speaker of the House won’t let me get away with any culinary terrorism, so expansion in my girth is largely down to our old friend Mr Beery-Pop. But I digress.

Anyway, bud, I’m sorry to tell you that you’re wrong and I’m right: The extra 628mm is, in fact, precisely the amount of extra string you’d need to circumnavigate the planet after a 20mm expansion of its diameter. I know, it still does my head in too.

Apparently, it’s all down to the circumference of a circle (or sphere) being locked in a non-negotiable relationship with its radius (and, therefore, its diameter) and our other old mate Pi. (Beer and Pi(e)s. Mmmmmm.)

And here’s where it gets really trippy: It doesn’t matter whether you add 20mm to the diameter of a bowling ball, the sun, or something half-way in between (like, Kanye West’s head) the extra string required to circumnavigate it will always be 628mm. Weird, huh?

But don’t tear yourself up over this, Pete. You’re definitely not the only bloke contacting me to take issue with this brain-teaser. But I’m sticking with my statement.

I reckon the real magic of this whole thing is that it’s so anti-intuitive. Experience has taught us that big things need big amounts of stuff to cover or wrap them. As we already know that walking around the planet would not be completed before lunchtime, it’s safe to assume that adding anything to that diameter would blow the circumference out of the water. Big mistake.

Remember the old pop-quiz at school: What weighs more, a ton of feathers or a ton of bricks? Of course, the answer is: Neither – they both weigh a ton. Or, remember: A plane crashes into a hill. On which side of the hill do they bury the survivors? Um, it’s not the survivors they bury, right?

We can take this a step further, too. Say you’re trying to track down a mis-fire in your Sunday car. You’ve changed the plugs but it’s still running on five. So you start changing more and more things until you’ve rebuilt the damn thing and it still won’t rev out cleanly. What made you so certain you really knew what you knew? Is it not possible that you got sold a dud spark plug? Did you swap the plugs around and see if the dead cylinder moved with the plug? Nope, you assumed it was stale fuel, carby, fuel filter, points, condenser, leads and, finally, a blown head gasket. And now you’re standing in a shed with your engine pulled apart and tears running down your grimy little cheeks. I know I’ve been there.

The point is that we shouldn’t be too quick to jump to a conclusion that seems right, even if the theory has proven correct in the past. Because, this time, it might not be. As a wise old mechanic told me: When we assume, we make an ASS of U and ME.


Calculated irrationality

dash.jpgHand operated hand brakes and floor mounted dip-switches

One of my favourite sections in Unique Cars is Morley’s Workshop and the often quite remarkable correspondence therein, but particularly Mr Morley’s responses to said correspondence. Some of Morley’s responses are, I believe, simply designed to generate further correspondence, sometimes irrational and outraged. But that makes for good reading and is to be encouraged.

In my case I want to refer to Morley’s response, in Issue 432, regarding handbrake positioning, and his mentioning of features that car designers discarded long ago. Quarter windows,  were great in my HD, but floor-mounted dip-switches? Really? And as for handbrakes, my current vehicle has the state-of-the-art electric item, positioned perfectly in the centre console, and oh so easy to use. If there’s any discernible delay in its operation, I haven’t noticed.

Eric Groszmann,

IT’S FUNNY you think I’m being deliberately controversial and provocative, Eric. But let me assure you, it all comes pretty naturally. Just ask Mrs M. And I really do miss quarter vents and floor-mounted dip-switches.

Also, I don’t think we’re going to agree on electric park-brakes. I dislike the way they require you to wait for them to disengage. I dislike the way they never seem to operate in the direction they should. I dislike that they require an electric motor to operate them. Most of all I would remind you that the original, manual park-brake lever wasn’t a broken concept and is lovely and tactile and engenders some mechanical sympathy.

To me, replacing a simple, mechanical, arrangement with one that needs whirring motors and a computer to do the same job is hardly progress. Maybe it is okay for a convertible roof which can be tricky to manipulate by hand. But for a spit-simple cable and ratchet, introducing electronics and motors is just being an arsehat and a show-off.

Look at electric power-steering and throttle-by-wire. Sure, both offer fuel economy benefits (unlike an electronic park-brake which does not) but both also offer less feel and feedback to the driver. Since my relationship with cars is about driving them, not bragging about their sophistication at the yacht club, I refuse to accept this new `reality’.

Just call me irrational and outraged. Anybody with me here?


Hello, Deed Poll… 

bmj98s.jpgIt’s not what you drive but the plates that are on it

Have I mentioned that I’ve got myself a pair of personalised number plates with my name on them for a one-off fee of only $319? All I had to do was change my name to BMJ-98S.

BMJ-98S (the correspondent formerly known as Richard),

NICE ONE. What’s your other half reckon about being Mrs 98S?



Wash 'n' go

washing-bucket.jpgRegular washing is a good idea. Bugs and brake dust can be corrosive and even ordinary old grunge can take its toll on paint. So yeah, wash it. But if you keep your car under a cover of any sort (even in a garage) don’t be tempted to cover up until the car has completely dried out. And that can take longer than you might think, because water can be trapped in little channels and folds in the metal under the car and only evaporate much later. The best way is to take it for a drive after the wash. Like you needed another excuse…

Brand loyalty?


Last month, I was rabbiting on about the piston from a 500cc motorcycle fitting a Toyota two-litre twin-cam from the 1970s. The link was that both engines had been developed by Yamaha. But it also reminded me of another weird combo I heard about. A mate of mine had a couple of Rolls Royce wedding cars with the big old 6.75-litre V8 on board. And he told me that, when one of the engines had to be rebuilt, the quote frightened the hell out of him. So he started looking around. And it turns out, the slugs and bottom-end bearings from a Bedford truck of some description were close enough to be interchangeable. Any more of these?


Write to Morley c/o uniquecars@bauertrader.com.au or Unique Cars magazine, Locked Bag 12, Oakleigh, Vic 3166


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