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Re: 1098 vs 1275
Posted: Tue Feb 03, 2026 7:16 am
by Wes
svenedin wrote: ↑Mon Feb 02, 2026 5:21 pm
geoberni wrote: ↑Mon Feb 02, 2026 4:14 pm
Wes wrote: ↑Mon Feb 02, 2026 12:50 pm
I wouldn't recommend a DIY endoscopy especially with equipment purchased from Lidl or eBay........
Stephen
Re: 1098 vs 1275
Posted: Tue Feb 03, 2026 9:58 am
by geoberni
Bill_qaz wrote: ↑Mon Feb 02, 2026 5:30 pm
geoberni wrote: ↑Mon Feb 02, 2026 4:14 pm
Wes wrote: ↑Mon Feb 02, 2026 12:50 pm
Engine not smoking, rattling in so much as a lot of tappet noise despite tappet clearances checked. No water usage, oil usage just the typical drips out the bottom!
God call re endoscope, i think Lidl do them occasionally.
All good point to think about. Thanks
Can I just clarify something here, Endoscopes are for medical use, being inserted into body cavities. They are much thinner and more flexible than Boroscopes.
Boroscopes are for industrial use, being more robust and having brighter lighting since they aren't going to burn someone internally....
You can get boroscope cameras from the internet that simply plug into your phone or a laptop for £5-£10.
Of course, on ebay, they will be described as
USB Endoscope Borescope Snake Inspection Camera 3 in 1 or similar catch all phrase.
I did say borescope Berni, cheap, linked to your phone. Comes with mirror to look in different direction.
Were as endoscope are often a pain in the butt
as many of us of a certain age probably know
Hence why I didn't include your part of the quote...
My first endoscope was the other end, to discover my Hiatus Hernia.
Re: 1098 vs 1275
Posted: Tue Feb 03, 2026 12:00 pm
by Bill_qaz
[/quote]
Hence why I didn't include your part of the quote...
My first endoscope was the other end, to discover my Hiatus Hernia.
[/quote]
Thats whats known as both ends of the spectrum (
spell check )
Re: 1098 vs 1275
Posted: Tue Feb 03, 2026 5:12 pm
by michael4
Slightly off the original topic and devoid of medical innuendo...
Unbeknownst to me the previous owner of our car had fitted a 1275 head on the 1098 engine, there's an invoice for machining the head but with no further info. I didn't realise till some time later when I noticed that there was a cutout in the edge of the battery tray to accommodate the heater valve and that the thermostat housing sat differently.
As far as I can tell manifolds and carb are still standard (though the inlet as no provision for a breather valve).
Surely changing head only would make very little if any difference? I can only assume that the car was sold before they got round to manifolds/carb etc.
Re: 1098 vs 1275
Posted: Tue Feb 03, 2026 5:23 pm
by philthehill
Changing the 1098cc head to a 1275cc head and still retaining the original 1,1/4" SU carb and manifold is of benefit. The bigger valves and better combustion chamber shape of the 1275cc head helps to get more mixture into the cylinder which results in a bigger bang. It has to be considered against the 1500cc 'B' Series engine only used a 1, 1/4" SU carb and ran very well with the small carb.
Re: 1098 vs 1275
Posted: Tue Feb 03, 2026 8:12 pm
by kevin s
if its rattling and the tappets are OK it could be the timing chain, a stretched chain also affects performance . For ours we rebuilt a 1098 with a raised compression ratio(9:1), improved combustion chamber shape , cleaned up ports a mild fast road cam and a mapped ignition, it currently has the std 11/4 carb and goes well comparred to the original but does feel throttled and runs out of puff around 3500rpm, I'm about to fit twin carbs and LCB exhaust, hopefully it will pull well throughout the rev range with this. We could probably get the same performace with a single HIF 44 carb but the twin ones look far faster!
Re: 1098 vs 1275
Posted: Tue Feb 03, 2026 9:11 pm
by MikeNash
Wes,
You might want to know how well an old and worn 1098 can go. Well, in about 1965/6 my mother had a BMC “Gold Seal” replacement engine fitted into what is now my Traveller (of 1963) and some 50 years later the engine was truly old and tired. However, the A Series engines are tough beasts and I found that with the valves ground in with care, the compression was good and with the carburettor and ignition adjusted as the manual requires, the Traveller was a speedy and reliable transport. It could cruise all day at 60-65mph (GPS figures not speedo-read) for which it would then return 35-38 mpg. For a few years I did runs from home to Newcastle up the M1 & A1(M), some 600miles+ there and back in a weekend, without qualms. The speed would be held for a couple of hours at a time and require full throttle for long spells when going uphill or up-wind. Sometimes it pulled a loaded trailer too. The A series can stand it, just see the mods that others make to their 1098s – and they don’t burst! My Trav’s maximum speed was 74-76mph (true) but above 70 you needed to wear ear defenders.
The downside for my old engine was that at speed the oil consumption rose to 150 miles to the pint (for which the “cure” was to buy the cheapest oil, Wilkinson’s 20-50; remember them?). With less oil aboard the oil temperature would climb to the 90-100C and the oil pressure fall to less than 40psi with only 5 at idle (and with the oil light flashing) but it all held together and was docile and smooth too. I eventually replaced it with another 1098 bought from Bmcecosse (of happy memory), which while good, quiet and abstemious on oil isn’t quite as quick, which makes me think that 1098s go best when loose!
So, my advice is check the compression as Svenedin says above (but do it with the throttle wide open – a brick on the accelerator?), set the timing and carb as the manual describes and go for it, foot to floor!
Regards from MikeN.
Re: 1098 vs 1275
Posted: Tue Feb 03, 2026 10:12 pm
by svenedin
MikeNash wrote: ↑Tue Feb 03, 2026 9:11 pm
Wes,
You might want to know how well an old and worn 1098 can go. Well, in about 1965/6 my mother had a BMC “Gold Seal” replacement engine fitted into what is now my Traveller (of 1963) and some 50 years later the engine was truly old and tired. However, the A Series engines are tough beasts and I found that with the valves ground in with care, the compression was good and with the carburettor and ignition adjusted as the manual requires, the Traveller was a speedy and reliable transport. It could cruise all day at 60-65mph (GPS figures not speedo-read) for which it would then return 35-38 mpg. For a few years I did runs from home to Newcastle up the M1 & A1(M), some 600miles+ there and back in a weekend, without qualms. The speed would be held for a couple of hours at a time and require full throttle for long spells when going uphill or up-wind. Sometimes it pulled a loaded trailer too. The A series can stand it, just see the mods that others make to their 1098s – and they don’t burst! My Trav’s maximum speed was 74-76mph (true) but above 70 you needed to wear ear defenders.
The downside for my old engine was that at speed the oil consumption rose to 150 miles to the pint (for which the “cure” was to buy the cheapest oil, Wilkinson’s 20-50; remember them?). With less oil aboard the oil temperature would climb to the 90-100C and the oil pressure fall to less than 40psi with only 5 at idle (and with the oil light flashing) but it all held together and was docile and smooth too. I eventually replaced it with another 1098 bought from Bmcecosse (of happy memory), which while good, quiet and abstemious on oil isn’t quite as quick, which makes me think that 1098s go best when loose!
So, my advice is check the compression as Svenedin says above (but do it with the throttle wide open – a brick on the accelerator?), set the timing and carb as the manual describes and go for it, foot to floor!
Regards from MikeN.
That all sounds very familiar. My 1969 car had the original engine which had never had any significant overhaul work done to it until last year. It was my car when I learned to drive at 17, my car as student and my every day car until my mid-twenties or maybe a bit later. The engine went rather well really, and had good compression but eventually it just started to use so much oil (100 miles to the pint) that it became annoying, especially for long trips. I remember on MoT to Holland in 2024 that we had to stop to top with oil much too frequently and I finally decided that was enough and the engine went off to be rebuilt. Now, after rebuild, the engine hardly uses any oil at all which always seems to surprise me after years of habitual, frequent oil level checks! Power wise, there's not a lot of difference but fuel consumption is definitely better. If I was only doing short trips I would still be using the engine in its tired state. The tired engine didn't just burn oil, it leaked it too and the faster it went, the more oil it used.
Ah yes, BMCEcosse (Roy). My car has the Wolseley 1500 brakes from his Traveller (which was sadly scrapped after an accident during restoration but the car lives on in small part in my car).
Stephen
Re: 1098 vs 1275
Posted: Wed Feb 04, 2026 7:13 am
by Wes
Great insights all
Much food for thought.
Thank you ever so much.
Re: 1098 vs 1275
Posted: Wed Feb 04, 2026 9:00 am
by myoldjalopy
To add to Mike and Stephen's comments, in the past, almost every engine that I have replaced has been because it started using too much oil, rather than its performance worsened. In those days, a lot of Minors were run as 'old bangers' and somewhat neglected. The only exception was the 803cc engine in my current car, because it was
very 'tired' - it performed less well than the first 803cc-powered car that was my first Minor, as that had an engine in tip-top condition. I upgraded the tired 803cc to the mighty 948cc engine!