Madabout Kitcars Forum

Madabout Kitcars Forum (
-   Marlin Sportster, Cabrio, Berlinetta and Roadster builds (
-   -   Restrictions to fitting larger engines? (

8 Valve Ed 5th November 2014 22:38

Restrictions to fitting larger engines?
This thread isn't really Marlin specific so if the Mods feel it would be better in another section please move it.

My Berlinetta original build was with a Ford Cortina 2 Litre engine/gearbox. A later owner fitted a Rover V8 3500 SD1 engine and auto gearbox.

While I love the Rover V8, having driven countless thousands of miles with them I am conscious of the extra running costs etc, 19MPG was good! Nowadays the cost of fuel is very significant, also the licence cost per mile is significant especially for low milage use.

I have a BMC A series 1275 engine and overdrive gearbox freshly rebuilt and surplus from another project.

If I were to fit the A Series engine and gearbox, I don't see any issues, I simply amend the V5c when I licence the car and that should be that. BUT... If for some reason I decided to fit the Rover engine and gearbox in the future, are there any regulations which may trigger for example an IVA, or some other inspection. I ask because I have some dim recollection of having read somewhere that it's OK going down in capacity but what would be more than doubling the engine capacity can cause issues in the regulations? I don't plan to alter the suspension, brakes or steering so they would be as they were with the Rover engine. I have searched but not come up with anything relevant.

As for performance I don't see it as an issue, I just want an open car to tour and enjoy the scenery, not to drive at high speed. I am already building the car with weight kept to a minimum so I don't think it will be significantly heavier than the Roadster. With a lowish Final drive (Transit?) and perhaps 14" wheels, it should climb hills well enough.

Chris Cussen 6th November 2014 08:32

The last time I changed an engine I needed a letter from an engineer saying that the new installation was satisfactory. However that was a VERY long time ago.

8 Valve Ed 6th November 2014 08:37

Hi Chris, was that requirement from the insurance or VOSA?

peterux 6th November 2014 21:36

I changed the engine in my Marlin Sportster from a 2.0 to a 2.8. I just changed the engine number and capacity by updating the V5. I think I sent a covering letter with a picture of the new engine in the car, picture of the new engine number and a copy of the receipt for the purchase of the new engine. I seem to think that the important bit is the receipt for the new engine?
No questions asked and V5 returned with updated info.


Chris Cussen 7th November 2014 07:51

As I said, a long time ago, but it was DVLA

cabrioman 7th November 2014 19:19

I changed the engine in my Hunter from a 2.0 litre Ford to a BMW 2.5 m20, I sent off the v5 to be updated, it took me 3 months to get the DVLA to give me back an updated V5 and as they have the original you can't tax the car while they have it.

They wrote to me asking for proof of where the replacement engine had been sourced from. I had to provide original invoices for the replacement engine showing fuel type, exact cc, engine number. Fortunatley the specialist BMW breaker I bought the engine from was really helpful and generated a new receipt with all the relevant information on it. If it had been a guy on eBay purchase I would have been stuffed.

You need to make sure you can supply that sort of detail or they will refuse to update the V5.

In my case it took about 3 letters, a couple of phone calls to the the guy in DVLA handling the case and a very helpful BMW breaker. I sent the V5 off in November 2012 and finally got the updated V5 in February 2013.

Patrick 10th November 2014 18:24

Went we converted the 2.5 to a 2.8 I sent off an updated V5 with the new capacity (same engine) and also told the insurance which put the price up a bit. Got a new V5 a little while later with the updated capacity.

8 Valve Ed 16th December 2014 11:26

Thanks Guys!
I have resolved this one, seen sense and reason eventually.

I was becoming frustrated at a total lack of progress with my Berlinetta build. I do not feel that BW 65 auto boxes which have laid about unused for 23 years are a viable basis for a build. The car was last licensed to the end of Feb 1992. Auto boxes can be problematic at the best of times but with the potential for hardened seals, cracked or swollen 'O' rings, age hardening and embrittlement of other bits inside the box, I felt there was a high risk of issues developing within days of putting the car on the road.

I do not have the budget to rebuild an auto box. I was baulking at putting a lot of work into a build with the high risk of premature failure built in. So given I had a perfectly serviceable 'A' series engine and gearbox from my Roadster, it seemed a good idea to install that, at least in the short term, to kick start the project.

I placed the 'A' series unit in the Berlinetta and it fitted well enough, in a corner of the engine bay! LOL It looked lost! I calculated and weighed the car and it appeared that with the 'A' Series unit it would only weigh just over 600Kg 'on the road', which was slightly lighter than when it was in the Roadster @ 650Kg on the road.

However, I looked at the gearing and available power, it would need a much lower final drive than the 3.44 which is in the car. I asked around for a local source of a Transit diff, and was pointed to a couple of chaps who had axles lying about, they were all the wrong type, front loading, rather than rear loading. That led to somebody who had a big collection of engines, gearboxes and other stuff. I was offered a transit 2.0 DOHC engine with an MT75 gearbox, which seemed a good alternative, however he stopped answering his 'phone? I then followed up a couple of other leads, MT75 boxes and Mondeo engines which seemed a good, cheap, reliable and available option.

But, I really wanted my Rover V8 lump. In the pouring rain I called at a local breakers yard I had previously never heard of, I enquired about a Rover Manual SD1 gearbox. I was sent to a remote corner of the yard where there was an SD1 front end mechanicals assembly. V8 engine, LT77 5 speed gearbox, and front suspension, wonderful! They must have lain there for at least 2 years, there were trees growing through it. The gearbox looked like it might be OK, but I didn't give the engine much of a chance. It was the gearbox I needed, so I did a deal.

New Marlin V8 engine

When I got the engine home it turned over OK so did the gearbox, which also seemed nice and tight on the engagement and shafts. In with a chance, I drained the oil from the box and no signs of water. So I stripped the engine, which to my amazement is close to perfect inside. Despite being open to the elements with one missing carb and no air cleaner, there was just one cylinder with one ring seized. There is slight water marking on that bore (#8) but no pitting, so I am a very happy bunny. All it needs is cleaning, a few gaskets and re-assembling. I freed the ring by immersing the piston in boiling water and gently working it loose. All the shells are perfect, the cam followers and the rocker gear are as new.

The gearbox is now sitting in position where the BW65 box was with a 'dummy' P5 block and heads, I need to make slight adjustment to the mountings to retain clearance because the castings are a bit different but otherwise it's a straight swap.

My weight calculations indicate I should come out at about 750Kg with the SD1 unit, and the 3.44 gearing looks OK, so I am happy again!

peterux 16th December 2014 23:03

Sounds like a great project Ed!!
A Berlinetta with a V8 will be a pretty cool car :cool:

Keep us posted on progress..........

8 Valve Ed 19th December 2014 13:37


Originally Posted by peterux (Post 62046)
Sounds like a great project Ed!!
A Berlinetta with a V8 will be a pretty cool car :cool:

Keep us posted on progress..........

Thanks Peter, I am starting to enjoy myself again!

I have almost finished modding the pedal box to incorporate a hydraulic clutch master cylinder.

Is there any interest here in body shaping? I have made myself an English Wheel and I am creating some of my own body panels from aluminium.

As I got my Berlinetta it had no bonnet or boot lid. I also feel some of the original fibreglass panels look a bit naff, they lack shape, particularly the scuttle and the front wings. I have made my own scuttle with a curved profile rather than the standard Marlin flat panels having a distinct central ridge where the hinge is. I don't like the large, absolutely flat areas; fine on a utility vehicle like a Land Rover but on a sports car, a 'body beautiful' - curved, is very important. Quite apart from the aesthetics which of course are subjective; large flat areas tend to show distortions and tend to flex far more than a single curve; a slight double curve or crown is even better than a basic flat panel, which to my eye looks 'cheap'.

While wheeling curvaceous and elaborate panels is a highly skilled art, simple, modest and straightforward panels are not that difficult with a methodical approach. I have done trial runs for each panel I have created at a smaller scale from scrap to find the snags in the shape. That way I can plan the best way to sequence the shaping. So far I haven't had any disasters or created a large heap of scrap aluminium!!

If there is any interest I am happy to share my (limited) experiences. So far I have made a kids Land Rover and a new scuttle for the Marlin. I plan to make the cover for the Marlin gearbox/clutch housing, the bonnet and side panels with louvers and hopefully a nice pair of front wings with crown rather than the basic flat slabs which come as standard.

Mike 19th December 2014 21:39


How about some photos............. ?

8 Valve Ed 19th December 2014 21:54


Originally Posted by Mike (Post 62114)

How about some photos............. ?

Hi Mike,

I have a few, but just for now this is all I have actually on Flicker:

Chris trying his hand on the English Wheel...

The new scuttle...

This was taken a while back with the Borg Warner type 65 box in place. I will take some more in the next few days of the current set up and the new clutch pedal box in place.

I still have to trim the scuttle panel around the doors. I have cleaned up the shrinking on the front of the scuttle rebate but in fact it will be largely covered by the bulkhead panel. The scuttle is formed from 1.5mm Aluminium sheet.

garyh 19th December 2014 22:01

Very interested Ed, have you seen what Axel has done on his thread?
I have bought a selection of anvils and a large bearing to hopefully turn into an English wheel at some point.

8 Valve Ed 19th December 2014 22:16

Hi Gary, No I haven't, would you mind posting a link or a pointer to which section please, I am trying to read my way backwards through the old posts in my spare time but I don't have that much spare time!!! LOL I haven't explored the whole site yet.

After a good nights sleep I did a search and found Axel's thread, only read one page so far but it looks a very interesting thread, many thanks for mentioning it. I will study it carefully later.

I have to admit I didn't turn up the wheels myself, I found them on eBay and 'did a deal' with the seller. The large wheel isn't perfect but for what I need it seems to get the job done. The frame is made from 120 x 80 x 5mm wall RHS, the legs are some 100 x 100 x 5mm RHS, I bought as offcuts form a local fabricator for a fiver each for about 6 ft lengths, I have used some more to build an engine crane... I am planning an engine frame attachment for the engine crane to make screwing the V8 back together a bit easier.

All times are GMT +0. The time now is 05:04.

Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Copyright Madabout Kitcars 2014