DRL152K Marina based roadster rebuild

[martinclan56]

Not a great deal has been happening on the Marlin front due to other, house related, activities. However those are nearly at an end so have been able to go to the man (Marlin) shed for short periods.
One of the weak spots on the Marina based Marlin is the steering rack. It has an internal bush at one end of the rack which inevitably wears out. It is a real pain to replace as:
A. The only replacements available are a polybush that is made in Australia
B. You have to drill out the peans on the inner rack ball joints to gain access.
Anyway I did that succesfully but now the rack is incontinent leaking oil from the pinion housing. Grrrr. And yes I did say oil, the Marina rack is oil filled rather than the more usual grease. Weird. I suppose it seemed like a good idea at the time.

To cut a long story short an (apparently) new old stock rack turned up on Ebay. Rare as hens teath and then some. I duly bought it and it's a good'un. The only slightly funny thing is the seller obviously didn't realise it was oil filled and the corrogated packing it arrived in was soggy to say the least!
Here it is after a bit of a clean up. Even the gaiters are in good nick. I half expected them to be perished in view of the fact it must be at least 40 years old! And the alluminium bits are all shiny as they were covered in some sort of wax for protection.

nos steering rack by Robin Martin, on Flickr

[phild]

This is coming along well and I like the changes and mods you have been doing to update it.

Cheers Phild

[HairyDave]

Re: DRL152K Marina based roadster rebuild

Very smart! When you mentioned bonnet bulges my 1800TC has L-R mountings and my carbs clear the bonnet but without going out to look I think the black spacers are narrower on mine and the front carb has a thin pancake filter. But mine is a Roadster.

[David]

Re: DRL152K Marina based roadster rebuild

That’s a nice looking donk.

[martinclan56]

Re: DRL152K Marina based roadster rebuild

Engine build now complete. Been a bit delayed with problems caused by poor quality parts. As the MGB is so popular you wouldn't think it would be a problem but there is pretty much nothing available from the "normal" aftermarket and everything seems to come from China. Having said that some of it is very good, but some of it absolute rubbish...
I have fitted a fancy rocker cover as the original was a bit bent, but in fact it is not a great fit so may go back to the original. And a new distributor which has an advance curve (allegedly) tweaked for stage 2. Was rather cheap though, although it looks made well enough, but it will be another 12 months or so before I can verify its operation. In the meantime I will have a go a stripping and rebuilding the original.
Some pictures.
engine10 by Robin Martin, on Flickr
engine11 by Robin Martin, on Flickr
The observant may notice the non-standard engine mounting rubbers. The original Marina ones are like rocking horse poo and so I have used Land Rover ones as suggested by the original Marlin build manual. These have the added advantage of lowering the engine slightly which I hope will give enough clearance for the fron carb to fit under the bonnet. The original bonnet had a couple of unslightly bulges.

[David]

Re: DRL152K Marina based roadster rebuild

Thanks Robin.

[martinclan56]

Re: DRL152K Marina based roadster rebuild

I’ve been looking at those seats for my Sportster, a local trimmer reckons he can make some nice tie on cushions for them. Are they OK?

They are suprisingly comfortable even without seat pads! They seem to be generally well made although a few of the rivets, used to hold the base to the top, are in a bit squiff. Easily corrected if you have set as many rivets as I have...
I paid less than what the seats are advertised from as he made me an offer after watching them for a while on Ebay. So - yes - I am happy with them.

In my other car (Pembleton) I used seats from Kirkey Racing. They are much, much stronger, originating in the stock car market. But they are also much, much more expensive. They are also less comfortable. I had seat pads made for them.

DSCF2262 by Robin Martin, on Flickr

It's a question of you pays yer money and makes yer choice - as they say.

Cheers, Robin

[David]

Re: DRL152K Marina based roadster rebuild

I’ve been looking at those seats for my Sportster, a local trimmer reckons he can make some nice tie on cushions for them. Are they OK?

[martinclan56]

Re: DRL152K Marina based roadster rebuild

I have pretty much finished the engine build now other than the water pump and sump.
The sump I have to swap from the original engine as the one that came with the replacement had been buchered somewhat. A bit of a pain as it means I will need both engines in the air at the same time in order to do the swap.
The water pump hmmm... the one I purchased from a well known MGB parts specialist was rubbish - the casting looking like a copy of a copy of a copy... But I think I have located something better now.
You can see from the pictures that I forked out on a vernier timing wheel. Reground camshafts (so I am told) frequently need the timing tweaking to get it 100% correct. Certainly true in my case as when I had selected the specified advance it was nowhere near where it would have been if I used the two dots on the original chain wheels.
And finally I couldn't resist trial fitting the exhaust manifold I purchased from the states. The hope is that this will help me get a side exit for the exhaust without too many tortuous turns or any cutting and shutting of the exhaust system.
timing1 by Robin Martin, on Flickr
engine6 by Robin Martin, on Flickr
engine7 by Robin Martin, on Flickr
engine5 by Robin Martin, on Flickr

And finally - purchased these from Ebay. Already a bit of a bargain, the guy that makes them reduced the width so they would fit the Roadster - FOR FREE!
seats by Robin Martin, on Flickr

[martinclan56]

Re: DRL152K Marina based roadster rebuild

Loving the build thread. Which servo and master cylinder combination are you using?

Servo is TR6 as they are still available new. As I recall the (dual) brake master cylinder is also TR6
Again available new.
Cheers Robin

[andyf]

Re: DRL152K Marina based roadster rebuild

Loving the build thread. Which servo and master cylinder combination are you using?

[martinclan56]

Re: DRL152K Marina based roadster rebuild

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

[jon_wilkinson]

Re: DRL152K Marina based roadster rebuild

Such a good feeling when you take a bit of a risk and it pays off. Hope the bottom end turns out as good as the top.

[martinclan56]

Re: DRL152K Marina based roadster rebuild

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

[martinclan56]

Re: DRL152K Marina based roadster rebuild

I have been making slow progress albeit going a bit from one thing to another.
The windscreen frame has to be one of the Roadster's main features doubling up as a roll bar. However I was never very happy with it in the "raw" state. It is bent from a solid steel bar with a slot milled on the inside to take the screen. This left very sharp edges and some hollows in it from the bending process. So I have taken the angle grinder and P38 to it. Looks much more acceptable now.
windscreen_frame2 by Robin Martin, on Flickr
windscreen_frame1 by Robin Martin, on Flickr

I have also completed a prototype door. The plan is to use a solid plywood core as in the original Marlin supplied door. However decent plywood is sooooo expensive now I made the proof of concept door from MDF. I have now skinned it in alluminium (left over from the Pembleton build). I am pretty pleased with the result and now happy to take the saw and router to the final plywood version. The latch is from a landrover, modified by removing the outside handle and lock barrel. I was going to use a Morgan latch but they are now over GBP70 each whereas the landrover one is GBP30.
door_prototype1 by Robin Martin, on Flickr
door_prototype2 by Robin Martin, on Flickr

Cheers, Robin