All posts by Ian Proudfoot

A long term Marcos owner who is determined to actually drive the thing one day!

Manifold Destiny

Now let’s get this engine running again. To make that happen I’ll need some throttle bodies and some sort of angled manifold. First stage – design the manifold…

The position of the throttle bodies will be defined by the need to clear various other engine components.  My initial plan was to make a wooden mock-up, then give it to a machine shop to mill a version in aluminium. Then I found a possibly better option. Protolabs is a company that takes your 3D model and returns a machined part in the material of your choice.

First problem: learn to use a 3D modelling programme. Here’s my first effort, not perfect yet but getting there…

Left inlet


Well, unfortunately my manifold design is too complex for the three axis milling process, so I will have to re-think this. I really wanted to avoid an ugly welded construction, but maybe that’s what I will have to accept.

Or I could try Carbon fibre…

The strip-down continues

I know that I promised something more interesting at the end of my last post, but I can’t do better than this…

Interior sound-deadening

During the first build, I really thought that I was close to completion. I had the engine running and most systems operating correctly. So I decided to install the sound deadening felt. Half of it was done with EvoStick contact adhesive, but that didn’t seem to work too well. So, on the advice of one of my ‘expert’ friends I used some nasty very sticky black mastic.  That was perhaps one of the last jobs I did on the car before it was mothballed for many, many years.

Back to the present and that old felt is in a very bad way. It made a perfect nest for mice. The evidence of several generations of small rodents was easy to see. They were very choosy about where the best nesting material was to be found, so the end of the passenger footwell and the inside of the passenger door were shredded. The other problem was the smell; that damp storage environment has left an unpleasant stale, mildew aroma inside the car.

It was obvious that all of the old felt had to go. The first important point is that you should wear a dust mask for this job. The mould spores and dust particles should not be inhaled. It only took a few minutes to strip out the bulk of the felt, but for each part I was left with a shaggy fur lining to the interior. The parts that had been attached with contact adhesive came off quite easily, but those that had been glued with mastic simply wouldn’t move. After trying a few things the only viable way was to soak the remaining areas with white spirit. Wait for a while then scrape it off with a blunt wallpaper remover. It is a nasty, messy and very smelly job. The worst part is that after several evenings of hard labour I’m still not finished.

The old EvoStick wasn’t eager to be chipped off either, but I was lucky to find some 3M Adhesive Cleaner in our local yacht chandlers. This makes the old glue go soft so you can just peel it away. The surface it leaves is just like new and it’s safe for use on GRP too, recommended.

Building a car in a single garage

One of the reasons that I didn’t re-start the build many years ago was due to a lack of space. In an uncharacteristic attack of realism  I was forced to admit to myself that that won’t change for the foreseeable future.

To get to the point where I could even fit the car in my garage took several months of de-cluttering, reorganization and the purchase of a large shed to hold nearly everything that was filling the space. We should have bought a bigger shed.

Now, having started to work on the car I realise that I need to clear even more room. The first problem was that I could only work on one side of the car. To get to the other side meant pushing the car outside and working on it from there, hardly ideal as we approach winter.

I now have a solution to positioning problem. I bought a set of these SGS wheel dollies:

Now I can easily move the Marcos around the tiny garage. What’s more the car is at a more convenient height.

Coming soon, some real progress…

The next stage in the build is to finalize the arrangement of the engine components. This is critical to the success of the Thor V8 installation. I need to fit in the following:

  • Two new Jenvey throttle bodies on special manifold adapters. Engine air inlet ducting and filtration.
  • Plumbing for the cooling system.
  • Plumbing for the oil cooler.
  • The entire air conditioning system. Condenser, Receiver/Drier, Evaporator and Heater matrix. Associated plumbing.
  • New manifold for the compressor.
  • New dual-circuit pedal box and cover
  • Fuse box and all of the wiring loom branches.
  • Re-position the serpentine belt tensioner.
  • Find a new location for the engine steady bar.

I have to do this next, just to be sure that is all fits. Also, any associated chassis modifications have to be done before it’s galvanized.

That’s all for now.


All the small jobs

I’ve been spending a few evenings attacking some of the smaller, less interesting jobs.  Some of these tasks have involved removing a few misguided ‘features’ that I tried out during the first build.

In preparation for removing the body I have had to dig out the expanded foam that I used to fill the sill voids. The idea was to save the sills members from rusting through by preventing road crud from attacking them. I now feel that the opposite would be true. The moisture would still find its way in but probably wouldn’t dry out so quickly which could hasten the corrosion process In any case its all got to come out so that the body can be removed. I won’t be repeating this experiment for the final build.

I did try to remove some of the body fixing screws and managed the grand total of just one, even using an impact driver! I will have to re-think this…

The bonnet now closes but the clearances are very tight on the back of the inlet manifold. I’m still deciding what to do about that. The engine is now resting correctly on its mountings too.

One thing that really will have to change is the sump. It’s far deeper on this engine than the old P6 V8. Ground clearance can only be 30mm, maybe less and that’s nowhere near enough for the Isle of Wight roads.

I picked up the Sierra differential, hubs and drive shafts for the IRS conversion. A lot of cleaning to do, but they seem to be in very good condition.

That’s all for now. Back with something more interesting next time.


Will it fit?

With the engine in place it’s clear that there’s quite a bit of work to do before everything fits properly.  We installed the Thor V8  with most of its ancillaries in place. Now I am removing parts that prevent the bonnet from shutting.

  1. The throttle body mounting had to go. That required the removal of the  entire top end of the inlet manifold – the part that looks like a bunch of bananas. I will be replacing the original single 68mm throttle body with two 48mm Jenvey units.
  2. The coil packs were already partially removed. Those may have to be repositioned, or I could just relocate the cabin air intake.
  3. Mounting lugs on the top of the  manifold are too high, so it’s the hacksaw for them.



There are now two more serious problems to fix. The inlet/outlet position on the aircon compressor is too high  and will only get higher with its pipes attached.  Perhaps there is a variant of the part that has a different pipe configuration?

Although I won’t be keeping the steering pump, I would prefer it not to be acting as an engine mount. When I can clear the engine steady bracket, I will gain another 10 mm of extra bonnet clearance.

Steering pump touches chassis

For some light relief while I had the inlet manifold off the car I  started trying to get a polished finish like the  show engine  that was shown a few posts ago.

More soon


Home at last

Today the Marcos came home to Bembridge for the first time. It’s been squeezed into our tiny single garage where the rebuild will begin.


The old engine has gone, it didn’t survive being left untended for so long. Although it was just about possible to turn it over by hand it was clearly in a bad way.

The new engine is a 4.6 litre ‘Thor’ V8 from a 2001 Range Rover. It came with all ancillaries including alternator, air-con pump, power steering pump, ignition system and various odds and ends.


20140922_165739The big plan for the engine is to replace the single throttle body and tapered plenum with two 48mm Jenvey throttle bodies. This modification is to give clearance between the inlet manifold and the bonnet.

I don’t expect that the power steering pump will stay, but the air-con pump will be used, but only if I can find a suitable compact system to plumb it into.

I will need a new low profile sump too, but that’s for later.

A Marcos moves

After what seems like endless delays, the Mantula finally left it’s hiding place of the last fourteen years.  At 9:30 this morning Steve from Island Classics arrived with his truck and trailer. In no time it was loaded up and driven away.




The next stage will happen on Monday. With the car at Island Classics, Steve will remove the old 3.5 litre V8 and drop in the 4.6 litre unit. This will be a trial fit for clearances. I hope I don’t have to make too many changes, but there may be a problem with the serpentine belt tensioner interfering with the steering universal joint.


With new engine in place the Marcos will be transported to Bembridge where the real work can begin.


A ‘new’ engine

I have to admit that the idea of starting the build in April was wildly optimistic, however I have made one big step forward…

I was never really happy with the very old 3.5 V8 that I had rebuilt back in 1984. I guess I have a lack of confidence in my skills as an engine builder – remembering the struggle to get the crankshaft main bearings to fit. I would always be expecting the worst. With all that in mind I was looking for a more up-to-date alternative. Ideally it would be a fuel injected 4.0 or 4.6 unit.

While looking around for a bodywork specialist here on the Isle of Wight I discovered Steve Matthews’ and Ray Lover’s ‘Island Classics’, a relatively new outfit but with a growing reputation for restoring Jaguars and other interesting older cars. While discussing the 30 year Mantula build with Steve, he mentions in passing that he has a spare, low-mileage 2001 Rover V8 4.6 ‘Thor’ engine for sale. It even had all ancillaries included, so it’s effectively ready to run.  Just what I need…

One day it will look like this:

V8 Thor show engine

today it looks like this:

Inlet manifold

Front view
Front view

The next step is to find out if I can realistically fit it into the Mantula’s engine bay. Despite appearances the Thor plenum is lower (but wider) than the more common GEMS system. Maybe some subtle bonnet mods will be needed? The other potential problem point is the alternator which may interfere with the steering linkage.

Feels like only yesterday

Last week I took a look at the Mantula to see if it was in a suitable state to move.  Yes if was filthy but that was to be expected. But I had forgotten just how many odds and ends were left inside and in the boot. No reason to keep them in there so I brought them home with me.

Now  I’ve just finished sorting and cleaning everything that’s worth keeping. That was a mucky job and I should have worn a face mask… Quite a lot had to go  including the main instruments which were badly corroded.  I wasn’t planing to use them on this build anyway.

I found an unused new set of  Mantula rear lights which I bought from the factory. I won’t be using them so if anyone needs a replacement set, make me an offer. These are the wide rectangular units with a curved mounting surface.

However, working my way through all of that old stuff made it feel like I last worked on the car yesterday, not 25 years ago! Best of all it’s really beginning to feel as if I can succeed this time.


Marcos Mantula: the never ending build…

Welcome to my Mantula blog.

After far too many years in storage the Mantula moves slowly into the sunshine.

Mantula emergesIt’s time to re-start the build of this beautiful car. This weekend I pulled off its dust sheets and pumped up the tyres. Then moved it out into the fresh air. Its great to see it again after so many years. But it does look terribly neglected. I really should have taken better care of it.

So the good news is that the tyres still look good and it was easy enough to move around.  So it should be relatively simple to transport the car to my garage/workshop.

The bad news is that the car has been home to mice, so the sound proofing is in a sorry state. There is corrosion on the frame where  the Hammerite paint has given up. The engine must surely be in a bad way too as the protective cap on the Holley carburettor has been eaten, perhaps by those mice?

Otherwise it’s much as I left it in 1999.  There is much work to be done, and I can’t wait to get started.