Marlin Roadster (Re)Build

[Patrick]

Awesome work Robin

[MartinClan]

I have almost (see below) completed the revised steering column arrangement. The column now exits at the bottom of the dash, instead of through it, and the steering wheel is angled at about the same inclination as the dash, instead of being almost vertical.

The arrangement under the bonnet loooks a bit odd due to the fact that the steering rack is mounted so high in the Marina. But it gives me a nice angle between the lower and upper steering column which the SVA people would be delighted with. The idea is, in a front end crash, the upper steering column is not directed straight into the drivers chest! It should also miss all the engine ancilliaries, fingers crossed.
steering_shaft by Robin Martin, on Flickr

From the bulkhead backwards the steering column is mounted on some sturdy, and adjustable, brackets. I made the steering column itself using some Triumph bushes and an alluminium tube. And, yes, the brackets do use exhaust clamps, but after a lot of thinking they seemed the easiest and sturdiest way of mounting.
steering_column3 by Robin Martin, on Flickr
steering_column1 by Robin Martin, on Flickr

I said almost completed.... I was very satisfied with the result until I offered up the pedal box and, despite carefull measuring, found the lower support bracket fouled the brake pedal. Grrrr - the air was a bit blue. Anyway, after sleeping on it I have come up with a slightly different bracket which should be fine. I'll post a picture when I have fabricated it. Which could be some time as my Ikea kitchen is due to arrive Tuesday. I have told the wife it's her Christmas present ;-)

Cheers, Robin

[MartinClan]

I have made a little progress inbetween kitchen fitting. I have remade the lower steering column mount so it now clears the pedals. While I was at it I bent the clutch pedal so it is now a more sensible distance from the brake pedal. (Perhaps the original builder had big feet!)
steering_column5 by Robin Martin, on Flickr
And it was pointed out to me that the angle that the steering UJ was running at seemed to exceed the 35deg recommended max. They were right! I have jiggled things a bit, mainly rotating the steering rack, and now the UJ is working within the 35deg. I could probably reduce the angle even further but I thought I would wait until a trial fit of the engine just in case I have to do any more rethinking of the steering shaft.
revised_steering_shaft by Robin Martin, on Flickr
Now back to the kitchen fitting.... It's too cold in the man shed anyway :-)
Cheers, Robin

[Mitchelkitman]

I hope you won't mind me saying..... I may be wrong, but I think it's the "correct way" for the Uj's on the shaft to be 'in-phase' ie, lined up so they are a mirror image so that when the shaft turns it effectively stays the same length if that makes sense. If out of phase the shaft won't stay straight as it revolves? Obviously more important for a fast-moving item such as a prop shaft, but still probably improves things even for a steering column?

[Mitchelkitman]

p.s I've just looked back at the photos and in the first one the alignment looks correct, in the latest one it maybe isn't?

[MartinClan]

Originally Posted by Mitchelkitman

I hope you won't mind me saying..... I may be wrong, but I think it's the "correct way" for the Uj's on the shaft to be 'in-phase' ie, lined up so they are a mirror image so that when the shaft turns it effectively stays the same length if that makes sense. If out of phase the shaft won't stay straight as it revolves? Obviously more important for a fast-moving item such as a prop shaft, but still probably improves things even for a steering column?

Took me a few minutes but I see what you mean. As far as I am aware it doesn't really apply to steering shafts. But I will do some Googling to check.
The problem with the first arrangement is that the UJ at the steering wheel end (the shiney new one) was running at about 38deg. According to the manufacturer (and some other wise sages :-) ) the maximum angle is 35deg otherwise you are in danger of wearing it out quickly and/or, in extreme cases, locking it up.

Cheers, Robin

[MartinClan]

Never buy an engine from ebay and someone you don't know were the words echoing in my head as I handed over my hard earned.....
Anyway the story is BMC 1800 engine (Marina, MGB etc.) for sale on Ebay. It had an almost unbelievable spec with a Vulcan gas flowed head, Piper camshaft etc etc and had never been run since its rebuild. Of course I smelt a rat particularly as it had had a quick blow over with black paint. Anyway - I persued it and the story had a certain ring of truth. Advertised by an older, and and possibly a bit naive, guy. He had purchased it for his MGB but then found it was originally from a Marina TC and wouldn't fit. The crankshaft spigot bearing is much smaller for a Marina. So he decided to sell it on Ebay and, not suprisingly as it wouldn't easily fit an MGB, hadn't had a lot of interest. So a bit of negotiation ending up in a price that was far less than what just the head was worth and the engine was mine. He even delivered it.
Today I couldn't resist any longer and started the checking process. The plan is to dismantle and re-assemble it anyway not trusing work that someone else has done. An engine built to this spec should have certain features, double valve springs, duplex timing chain etc. And I am pleased to say it all looks good so far!
The head has clearly had a lot of work - you can see the porting through intlet and exhaust ports.
engine4 by Robin Martin, on Flickr
engine3 by Robin Martin, on Flickr
And it has the requisite double valve springs and duplex timing chain.
engine2 by Robin Martin, on Flickr
engine1 by Robin Martin, on Flickr

The next step is to get it on to the engine stand and pull it apart a bit more. But so far looking good.....

Cheers, Robin

[Mitchelkitman]

That reminds me of the first time I used Ebay...... We were moving 19 years ago, and I'd bought a TC engine from the scrappy a few years previously and gleaned the head and front pulley from it (all it needed was a slightly larger fan belt) to use on my MGB engine. Anyway, back to the story. In my Ebay nativity I started it off at 99p as I wanted it shifting as I didn't want to take it with us. Guy 'won' it for

[Mitchelkitman]

That reminds me of the first time I used Ebay...... We were moving 19 years ago, and I'd bought a TC engine from the scrappy a few years previously and gleaned the head and front pulley from it (all it needed was a slightly larger fan belt) to use on my MGB engine. Anyway, back to the story. In my Ebay nativity I started it off at 99p as I wanted it shifting as I didn't want to take it with us. Guy 'won' it for 1.20. he turned up in a battered old car with all the family (Wife and 2 young kids) having driven from the Midlands to south Essex. he got out of the car saying "that was handy, I work at an engine reconditioners and have been looking for one for nearly a year - that will do nicely, can you give us a hand with getting it in the boot? Here's your 1.20, I raided the kids piggy bank"
I'd have at least given 10, having just made that statement, it probably had 5 scrap value! Anyway, off he went on the journey back, and I wondered if the floor of the old car would support the block all the way

[MartinClan]

I have now completed the dissassembly and reassembly of the head. It's now resplendant in MGB maroon which I understand would have been the original colour. Everything looked pretty good. The head has been gasflowed to what I suppose is stage 2. I am no expert but it looks pretty much as Peter Burgess describes in his MGB tuning book with the exception of hardened exhaust seats which it doesn't seem to have. Which leads me to think all the work on it was done many moons ago.
stripped_head by Robin Martin, on Flickr
reassembled_head by Robin Martin, on Flickr
During the strip and reassembly process I also cleared out all the waterways by blanking off the thermostat position and filling it with a solution of Rust Destructor and letting it soak for several days. It seems to have done the trick.
derusted by Robin Martin, on Flickr
While I was at it I also measured the combustion chamber volumes so I could work out the compression ratio.
combustion_chamber_vol by Robin Martin, on Flickr
Using the formula in Peter Burgess's book:

Engine size with +30 overbore = 1834cc. Cylinder swept area = 458.5cc
Combustion chamber volume as measured = 41cc
Clearance volume = 6.5 + 2 + 4.5 + 41 = 54cc
Compression ratio = (458.5 + 54) / 54 = 9.49

While I was at it I though it would be fun to work out the potential 0 to 60 time. Again using a formula from Peter Burgess.

0 to 60 = (2 x W / T) to the power of 0.6
W = weight – say 750 kgs = 1650 lb
T = torque – say 120 lb/ft (figure from Peter Burgess book for an engine with similar configuration)
0 – 60 = 7.3 seconds
So - no slouch then....

Cheers, Robin

[Patrick]

Nice, like the colour. Sonuds like it'll be pretty peppy.

[peterux]

Yes, that does look nice and it has cleaned up well.
Looks like that engine you bought was a really good find.

[MartinClan]

I have been looking for ideas that would help to bring the exhaust out of the side of the car as Marlin intended. Marlin supplied a special exhaust downpipe which allowed this but it was a very tortured design and probably not good for gas flow. And of course it's long since you could obtain it. I even tracked down the manufacturer (Double S) and they confirmed that had binned the pattern. But after a lot of Googling and general phaffing about I have purchased this exhaust manifold - currently on its way from the USA.

patriot h4800 exhaust by Robin Martin, on Flickr

It's a 3 into 1 design, ending in a 2" pipe, that hugs the block. I reckon with a bit of luck I should be able to bring the exhaust out the side either under or over the chassis rail.
So the next question is does anyone have any experience of silencers? There are loads for sale on Ebay, most of which I guess are from China and of dubious quality. I am looking for something that is not outrageuosly loud, but not too quiet either.....

Cheers, Robin,

[AlanHogg]

Didn't SS also make the original silencer?

[MartinClan]

Yes I think SS made the complete system. But, although they remember making it, they no longer have any of the patterns. Or so they told me.

Cheers, Robin

[Mister Towed]

Pair of Monty Python 'Black Knight' helmets for Halloween costumes?

[MartinClan]

Bit of a giveaway now as to what they will be...
first_fit by Robin Martin, on Flickr

[MartinClan]

After several months of DIY I finally have some time to spend on the Marlin. I really should be completing the resto of the chassis but I fancied something a bit more interesting so decided to trial fit the front suspension. The Marina uses an odd setup for the front suspension using torsion bars and trunions, based on that used by the Morris Minor but, unfortunately, having no common parts. Parts are as rare as hens teeth....

The standard problem with the upright is lack of maintenance causes the lower thread on the upright to deteriorate. Ultimately the trunion can part company with the upright. Mine were no exception.

upright rusted thread 2 by Robin Martin, on Flickr

I was able to track down, thanks to the Marina Owners Club, some new old stock of "Walford Trunions" which were a period fix for the problem. Basically a new threaded sleeve is screwed on to the old damaged thread and a new oversize trunion fits to that.

original and walford trunion by Robin Martin, on Flickr

You are supposed to fit the new threaded sleeve using the supplied threadlock but that was a bit suspect being 30+ years old so instead I bonded it using an industrial Araldite. Jobs a good-un. I should say that it is also tightened up to 100 Lb/ft as well!

inner component of walford trunion by Robin Martin, on Flickr

walford trunion fitted by Robin Martin, on Flickr

Finally I fitted all the bits up to the car. The Marina uses a lever arm damber but on the Marlin this is replaced by a Mini upper suspension arm and a conventional damper (not fitted yet)

front suspension trial fit by Robin Martin, on Flickr

The critical point is that the torsion bar should pass through a hole, on the chassis where it is finally fixed, without any lateral or vertical tension. This is also the rubbish part about Marina front suspension as it makes it pretty much impossible to play with the castor or camber. Anyway after a bit of fettling it's a great fit.

torsion bar position by Robin Martin, on Flickr

Now that I am happy it fits, and I am not missing any major bits, I can take it all off again and complete the cleaning up of the chassis!

Cheers, Robin

[Mick O'Malley]

I fitted those 'over trunnions' to both my Marina saloon and Ital estate back in the 80s. Great bits of kit!

Regards, Mick

[peterux]

Nice work, Robin.
Was there a reason for the bottom trunion being threaded? It seems an odd thing to do?
How do you keep the new thread lubricated, maybe some waterproof marine grease?