Fast Marina Magazine

Hi there

I have been recommended your forum via the marlin owners club of which i am a member.

In 1992 I built a marlin roadster kit car based on a 1979 marina 1.7 O series engine. The kit used most of the running gear, wiring loom etc. I am starting a major refurbishment project after having not used the car for more than 15 years.

Unfortunately I had to store the vehicle outside for a considerable period and i have found the engine has seized. I either need to rebuild or replace it. To ease the process i would like to replace the 1.7 like for like or if the engine mounts are the same i could possibly use the 2.0 version.

I would be most grateful for advice on:
Compatibility of 2.0 and 1.7 engine mounts
Availability of engine replacements or parts if not complete engines.

Many thanks

Mikeyp

O Series stuff is not over easy for parts to come by O1 blocks and head are the same There is a difference in late and early heads with reference to the water outlet pipe for heater at front of head. Thermostat housings are made of unobatinium and go porus Sherpa engines pop up on ebay in 2.0 very occasionally. SD1 2.0 very infrequently. Meastro Montego (O2) heads are different again i think the block will fit as Clayton Speed on here has put T series Turbo in his car said engine mounting bolted straight on the T series is as Development of O Series.
Dave

Pistons, rings, bearings, gasket sets and valves for Marina 1.7 and Princess 2.0 are available from this New Zealand company http://www.bowdenengineparts.co.nz/

Dave / Bryan

Many thanks for your responses, much appreciated.

Do you know if the 1.7L and 2.0l are interchangeable from a engine mount and gear box perspective?

Welcome Mikeyp,

All O series engines are interchangeable by way of their mounts. The differences are, as David says in their cylinder heads, sumps and ancillaries.

The 2ltr engine is simply a stroker 1700 with a different crank, rods and pistons. If you could find the parts then a 1700 can be converted to a 2000 as has been done by forum members in the past.

Possible Options

If you can get hold of a montego/maestro O series (all 2ltr) then your mounts, backplate, clutch and flywheel will bolt on. You would need to retain the cylinder head and convert to EFI or use your carb inlet/exhaust manifild on the opposite side to where it is currently located. You can't swap cylinder heads since the oil feed is different .

Princess/Ambassador engine (if you can find one) will fit with your mounts, backplate etc. These can use the Marina heads. IF you can find a HLS Ambassador (more chance of finding a needle in a haystack) then they have a twin carburettor manifold. (I have manifold if you were feeling adventurous).

Rover SD1 2000 complete engine as above but already in RWD format. Very rare and like any of the above would need a complete rebuild.

One other possibility is getting hold of a T series crank (all 2ltr), rods and pistons (NASP) then fitting these to your O series block. You would need a T series oil pump since the crank nose is bigger but they use the same bearings as the O series. You could then use your block and head. I've not done this myself but have had a few T and O series engines apart recently and can see the possibilities.

The final option would be to fit a T series engine in NASP or Turbo format. All the same mounts and your backplate, flywheel and clutch would fit. There are a fair few parts needed for this because of the EFI but the engines are still about in one form or another. Cylinder heads/blocks would need a rebuild as most with 50K+ miles on will show poor compression at this age. Parts are still obtainable from various suppliers.

My Marina had an O series turbo engine fitted that came from a Montego and was a hoot, I've now fitted a T series turbo and it is a blast. Great engines the O, M and T series.

Hope that helps.

Ben

Ben

Thank you for such a detailed response, something to chew on. I have found a possible ex factory crated o series engine, but still a waiting feedback on its availability, price etc, so I will do some homework on your suggestions above as they may be my only real option.

Kind regards

Mike

Hey Mike.
I have built several 2 litre O series engines by simply using Austin Princess cranks and pistons in the 1.7 block.
The 2 litre pistons are much shorter both top and bottom to 1700, so would likely exhibit less bore friction in use.
I used 1.7 conrods and could detect no difference between either examples.
I used both 2 litre and 1.7 camshafts as they differ. The 2 litre cam has a more aggressive profile and potentially yields more power, but the 1.7 cam seemed to give better low down torque which was a much more user-friendly characteristic.

Cranks are identical other than the big end journal offset..

On eBay now:
https://www.ebay.co.uk/itm/Morris-Marin ... SwuoZfcxDW

Interestingly that is not one of the later 1.7 O series engines.
The later units did away with the oil filler cap on the cambox cover and instead mounted it from the blanking plate on the right rear side of the crankcase.
I still have one of those engines as the starting point for my ultimate O series engine build.

Looking forward to that...

Looking at the picture of the piston and con rod the Gudgeon pin is nearer to the piston crown on the 2lt piston. This would allow for identical connecting rods to be used with the two different stroke lengths
Dave

Found the cam timing specs, 2000 has longer duration exhaust timing, and more overlap :- Interesting to see how the power outputs compare between the various engines fitted to the Marina (and a couple that weren't).

Interesting to see that the 2 litre TC managed 100bhp albeit at significant revs.
I think with some head work I may manage a little more, although I would love to mount a pair of 40mm Webers for the win.
I do have a pair here, but would need to have a manifold made, so the twin HiF setup on my Rover inlet manifold will be the first trial.
I have an aftermarket camshaft which I should be able to use thanks to some shims supplied by a forum member.

There are many advantages to be had by using the 2 litre setup, and if faced with the necessity of an overhaul anyway it makes sense...

52-55bhp/litre seemed to be the BMC/BL standard for sporty variants, so the 2000 should be good for 110bhp with a similar cam, inlet, exhaust and compression ratio as the 1800TC and 1750TC (and the Mini Cooper).

Interestingly, the 1750 TC seems to have got all it's extra power from a higher compression ratio (9.5:1 vs 8.6:1) and the twin carbs, as the head and cam and exhaust manifold are the same on the single carb variants, so just boosting the compression ratio of the 2000TC to 9.5:1 might gain that extra 10bhp.

Both 1700 and 2000 O series engines run 9.0:1 standard.
I have considered increasing this by skimming the head, but I fear it would involve removing all the valve seats first, as they are either flush or slightly proud of the head surface.
The 2 litre starter motor is already on steroids...

I don't think skimming the head the head will raise the compression as the head is a Heron head, so has a flat surface and combustion chamber is in the piston crown. The Compression ratio would be raised by reducing the size of piston crown Ie 1.7 pistons in a 2lt stroke but the Gudegon Pin height is different and the piston would protrude out of the bore. This would need some looking at maybe enough material to skim the piston crown. Conrod angles would then be wrong leading to different piston acceleration. How much this would matter in practical terms it either a suck it and see job or some clever maths
Dave