Hi

Thanks for your help identifying the 5MB engine in my early series 2.
Please see below (the first pic) the exhaust manifold to the 5MB engine.
The other 2 pics are of the exhaust manifolds from 2 other 2.25 petrol engines.
The one on the 5MB looks bent - the other 2 are straight.
Is it a different manifold or do I need to go to the optician?

Thanks in advance

Peter

Can't see from pix, can say that later 5MB in 90/110 2.25/2.5 11H/17H petrol have a different manifold again. The issue is they bring down-pipe further forward than Series exhaust. Squarer to look at. See pic.

But, and here's the real point - for your purposes this matters not. Yours don't look like that. Appear stock 3MB petrol, stock 3MB diesel, or series era 5MB thus fits respective stock petrol/ deseasel.. Strangles a bit, I've run 3MB petrol manifolds on 2.5 5MB 17H petrol in the past.

Thus whatever you have there, it's series era S2/S3 etc, don't fret - it'll go.

And if you're that way inclined I'd have that 5MB out to a proper 2.8 Litre in a heartbeat.

https://www.900club.org/viewtopic.php?f=7&t=1637

Thanks Nobeardxxxxxx

Thanks for your help. Very interesting website. The engine is coming out as it has been stood for about 12 years - not sure what to do with it yet.

Another thanks for the link Topknot.

Confirmed that these manifolds are hard to find now.

Craddocks have one.

£510 inc VAT. 

I hope I don't crack another one!

I'm running my 2.5 on Series 3 inlet and exhaust manifolds and Zenith 36IV. It goes very well and the Zenith is less troublesome than the 2.5's twin choke Weber and saves having to convert to a cable throttle.

Your block has the reinforcing X ribs on the side that would make it a 5maingearing.

Quote from: Alan Drover on Apr 09, 2024, 05:25 PMI'm running my 2.5 on Series 3 inlet and exhaust manifolds and Zenith 36IV. It goes very well and the Zenith is less troublesome than the 2.5's twin choke Weber and saves having to convert to a cable throttle.

I am very tempted to follow suit AD.

But the stubborn rivet-counter within me keeps making me think I should endure with the Weber.

I started up the very early (now tax-free) One Ten with the 2.25 petrol engine and Weber carb, this morning for the first time after its Winter lay-up.

Having been a total pig all last Autumn, it decided to perform well today.

I don't expect it to last - and if it drives me up the wall this summer, I think my resolve to resist conversion might well disappear!

I did wonder whether running a 2.5 on a carburettor jetted for a 2.25 would result in a weak mixture. My fears were unfounded as subsequent plug changes showed that all 4 plugs were exactly the same shade of a brick red colour and there's no sign of overheating.

Quote from: Alan Drover on Apr 10, 2024, 06:32 PMI did wonder whether running a 2.5 on a carburettor jetted for a 2.25 would result in a weak mixture. My fears were unfounded as subsequent plug changes showed that all 4 plugs were exactly the same shade of a brick red colour and there's no sign of overheating.

It rather depends on what we're trying to achieve? For a limited-miler toy none of this matters. You're correct, you fears are unfounded. However, if we stop for more than a second it's clear there's more:

1. If the yardstick for stoich is plug colour, we could run 0.95-1.05 and it's doubtful plug-colour would indicate differences. Plug-colour will indicate something wildly out, yet it'd be too broad a measure. Plug-colour is more akin to reading tea-leaves, and sorting your lawn-mower. A yardstick for subtle carb differences?
2. LR's own 2.25 5MB as thrown in the first 90/100 had a Weber 32/34 DTML.
3. LR's own 2.5 5MB as thrown in the first 90/100 had a Weber 32/34 DTML.
4. They are not the same carb. Jetting differs.

This was the era when LR had the Japanese and emission regs snapping hard at their heels. If plug-checks and slapping the same carb as the 2.25 was 'good-enough' to come to conclusion, they'd have done so. The Japanese and emission regs also forced LR to develop an improved exhaust-manifold on the 5MB 2.25 and thus the 2.5.

If we install a proper wideband lambda we'll see the differences. Which'd be what LR did at development, and why the spec. differs.

Is it wrong to put the Series era manifold / carbs on your 5MB 2.25/2.5 blah? Of course not. As said previously, it's what I had at the time... I outright admit doing this for a while. Will it run well enough for a limited-miler? Of course it will.

And be clear... it worked for 'Gypsy Rose NBNTP'.


Was it a emphatic lash-up? Yes.
Did I choose not to think too hard? Yes.
Did it suit me to insert opinion over fact. Yes.
Could I pretend it was good. Yes.


Not for the purist, however I'd consider a 5MB 2.25 swapped out to a long-stroke 200TDi crank to achieve 2.5/2.8 the ultimate Series LR. Since writing that swap/conversion post I've moved on, these days I've extended it to closed-loop injection. That is 'rather' excessive. Not content for this forum, here we shudder at the thought of micro-chips in our flasher-relay? What it does show is how far you can take a 5MB.

Look after your 5MB, not for those of a nasal persuasion, yet in my mind the connoisseur-choice.

As an aside, when I was speaking with one of Land Rover engineers about the 2.5 Litre  just after it was launched, he did say the it was not as efficient at higher revs compared with the 2.3 litre  due to the longer stroke resulted in greater pumping losses in the crank case . ie moving air between the bores as the pistons rise & fall.

Yes, that sounds about right. Generally the 2.5 delivers slightly better economy and a useful gob of power, however... try to thrash one, those gains are soon lost. Pretty obvious really, faster is never a free-lunch.

I've thrashed mine and it goes very well. It will exceed the 70 limit if I let it. Economy is on a par with the 2.25 but I believe the standard  Weber delivers less mpg.

Quote from: Alan Drover on Apr 12, 2024, 02:44 PM...Weber delivers less mpg.

Er, more. That'd be why the Weber 32/34 DTML was fitted. It'd make little sense at the time to fit a worse carb. One from a prior time? Evidence is all around:  it's found on virtually every hatchback from the era... the list is endless, every manufacturer had them :

VW Golf, Scirroco, Ford XR2/ XR3 and anything CVH, near all of the Fiat range, Renaults, Alfas... ever the the humble Metro. They were everywhere. These manufacturers along with LR specc'ed the Weber 32/34 DTML to cope with emissions that prior generations of carb couldn't meet. Weber 32/34 DTML gave better metering.

That is not to say they were vice-free. If... that's if... you can get a good one, the Weber 32/34 DTML is the best carb ever fitted to an LR. Unfortunately the word is 'if'.

The survivors aren't likely to be much good now, few XR2s and 80s hatchbacks survive today, thus those we see are on LRs, and - as is par for the course - LR never really got carbs right. However, 'if' you've got a good one, not clogged-up mit 40 years of crud (unlikely), they're excellent. Hatchbacks from the era did not suffer carb probs.

The hate doesn't stand scrutiny, it comes from the woe in finding one now, 40 years hence, your stereotypical owner, and part-time use isn't going to help. They're almost impossible to unclog, and complex. I've got four here, put thru' an ultrasonic, only one is any good. It's the one I've had in regular use.

Thus,  the word remains 'if'. Thus broadly not a good choice today, only not because they are bad per se.

Find the double solenoid version with its associated NRC9772 swirl pot, and a good one. As against anything stock LR, you'll not do better, that'd be why they fitted them back then.

I'd rather believe my late Land Rover dealer mate who part exchanged the 2.5 for my old 2.25 which had a Turner unleaded head and told the me that the Weber gave less mpg.
 I'm sticking with the good old Zenith as I have 3 rebuilt spare ones. The engine performs very well, pulls strongly in overdrive top and on long runs I get mid 20's mpg and between 16 & 18 driving short journeys. The engine was fitted in 2002 and I fitted a DD rebuilt distributor with Pertronix electronic ignition and a BFS rebuilt Zenith in about 2012, timed it by ear and the only maintenance necessary thereafter was oiling the throttle linkage, taking the play out of the linkage, oiling the distributor mechanism and a new distributor cap.
"If it ain't broke, don't fix it."
I'm very pleased at the way my 2.5 runs and to me that's all that matters.
The humble Metro was fitted with an HIF SU.

I have four Weber 32/34 DTML carbs currently on vehicles. Three on 2.25 Ninetys or One Tens, and one on a factory fit 2.5 petrol Defender.

Every single one has let me down in one way or another, often dumping me at the side of the road.
I never had this with a Zenith, the original (non-copy) ones were worry-free.

With regard to clag in the tanks, I have had these carbs cleaned ultra-sonically and rebuit, until they run fine and then fit one or two fuel filters in front of them.

They will still suddenly decide either to not start when hot, or not accelerate or not idle.

A carburettor should not only work when it is new, it should keep working.


I know several people, long time in the trade who say throw them away and fit something else.

That's not exactly a recommendation....


I also have friend who had a total nightmare with this carb on the 2.5P engine in his SIII, such that he was going to throw in the towel and sell it.

As a last resort, he bid and bought a second hand Weber on eBay.

He fitted it, and it has run perfectly ever since,

So yes, if you are VERY lucky you might find one that actually works.

But should any carburettor depend on you winning the Weber Carb Lottery?