Rebuilt 1275-running a bit "out of sorts"

[ndevans]

Yes, it's an 88deg thermostat. I think you raise a good point there. Although the engine hasn't done many miles since rebuild, it has spent the best part of a year out of use whilst I did other things. It's worth a flush, and I'll check the thermostat at the same time.
I don't think the mixture is too weak-I have a colortune, and it seems ok, but I am probably at the limit of my ability to set it up timing & mixture wise.

[ndevans]

Tested the thermostat this evening. It's an 88°, and I also have an 82° spare. Both operate correctly, the 88 maybe opening a shade early, but certainly fully open by 88°.
I will flush the radiator & block over the next couple of days.

Cheers N

[ampwhu]

out of curiosity, did you use the original fuel line to feed the engine/carb?

reason i ask is i'm building a 1275 engine and was wondering if the standard 1/4" fuel line is sufficient or whether a 5/16" would be better. I'm going to use a HIF44 carb.

[ndevans]

out of curiosity, did you use the original fuel line to feed the engine/carb?

reason i ask is i'm building a 1275 engine and was wondering if the standard 1/4" fuel line is sufficient or whether a 5/16" would be better. I'm going to use a HIF44 carb.

Yes, I did use the original braided line, but I'm now using a non-braided fuel line that is (allegedly) resistant to modern fuels. It's the same gauge, 1/4", I've done this because I don't like the idea of cracks appearing in the rubber that aren't visible.

[liammonty]

1/4” is fine on my Wolseley Six which can comfortably drink double what a Minor does, so you’ll be fine.

And re braided lines, totally agree with not using the modern braided lines as the quality is not what it was on the originals, and you don’t see the deterioration until it’s too late.

[ndevans]

I cold flushed the block, radiator & heater radiator tonight, using the hosepipe. All seemed good, a little crud may have come out, but not easy to tell as it was getting dark. Certainly nothing seemed blocked. I will order a 7lb cap, reassemble, and test over the weekend.
As an aside, draining the cooling system is a pain on my car, as my radiator hasn't got a drain tap. I have to drain by removing the bottom hose. There is a bolt at the bottom of the radiator, but I can't shift it. I think it is brazed in. It is so solid that in trying to turn it, I have actually warped the bottom radiator tank! I don't want to try heat on it, I daren't risk damaging it.

[Murrayminor]

Does the Marina engine have a water tap on the block?

[ndevans]

Does the Marina engine have a water tap on the block?

Not that I can see.

[Murrayminor]

I'm not that clued up on the marina engine but a few of the engines, it may just be the 1098 have a water tap at the rear of the block under the exhaust manifold. It assists with flushing the block, in fact I seem to recall putting a hose on one and reverse flushing the system with the rad uncoupled.

[philthehill]

The 1275cc Marina engine does not have a factory fitted drain tap at the R/N/S of the block it has instead a drain hole fitted with a threaded blanking plug which has the same thread as the drain tap..
You can fit a drain tap if desired. I have fitted a brass drain tap (same as Minor) to my Marina engine for ease of draining and flushing the block.
The 1275cc Midget/Sprite engine also has the facility for draining the block and the fitment of a drain tap.

https://www.moss-europe.co.uk/tap-water ... soc=417382

[ndevans]

The 1275cc Marina engine does not have a factory fitted drain tap at the R/N/S of the block it has instead a drain hole fitted with a threaded blanking plug which has the same thread as the drain tap..
You can fit a drain tap if desired. I have fitted a brass drain tap (same as Minor) to my Marina engine for ease of draining and flushing the block.
The 1275cc Midget/Sprite engine also has the facility for draining the block and the fitment of a drain tap.

https://www.moss-europe.co.uk/tap-water ... soc=417382

Is this it?

IMG_20200904_102632~2.jpg (1.04 MiB) Viewed 7028 times

[Murrayminor]

That's the one.

[ndevans]

Ok thanks. Next question:-what size is the bolt? A 3/4" AF spanner is a bit loose, 19mm is more loose, 18mm too tight. I've tried measuring across the flats with a micrometer, as best I can, and it seems to be 18.5mm!

[philthehill]

The standard size drain plug has a head of 3/4" A/F.
18.5mm is 23/32" so you could try a spanner or socket of that size.

Note: there are no metric sizes on a Minor 803cc/948cc/1098cc or 1275cc engine - they are all imperial / A/F.

[ndevans]

Got it off with a 3/4" socket in the end. It's definitely nearer 18mm though, as seen below, 18.15mm according to my Vernier. The threads are bang on 13mm dia, but the pitch is not metric, it's 19 tpi. Odd.

IMG_20200904_205807~2.jpg (786.84 KiB) Viewed 6982 times

[philthehill]

Forget the metric options - the coolant drain plug threads in the block are imperial.............1/4" BSP x 19TPI parallel thread.

The drain plug has parallel threads with a sealing washer - but the drain tap has either 1/4" BSP taper or parallel threads (dependent upon style of drain tap) with sealing washer. Sealing of the taper threads is obtained by the taper threads tightening in the block threads.

[ndevans]

Ahh.....BSP. That explains why I couldn't find a 19tpi thread in my UNF chart! Ok thanks. I'm going to Charlie Wares tomorrow anyway, I'll see if they have one, if not I'll order from Moss.
Thanks.

[ndevans]

Ok, got it all back together now, had to re-use the drain plug as they didn't have any in stock. I flushed the block through the drain plug, all seems clear. Ran the engine for about 20 min with the 4lb cap on, no sign of overflow, but I haven't been for a run in it yet.
Edit: the water pump turns freely without the fan belt connected, there is no sign of worn bearings, the fan belt may have been slightly loose, but only a little, it's now tightened up to 1/2" play between crankshaft pulley and alternator.

One question-is there a different bottom hose available for a 1275 engine? The head on a 1275 is a bit deeper, the block is slightly taller, the thermostat housing sits at a different angle, all of which means the pipe that runs along the top of the cylinder head does not align with the bottom hose heater take off, only just reaches it, and barely clears the thermostat studs. Can I run a length of hose from the heater to a short stub pipe in the bottom hose take off?

Cheers N

[philthehill]

The 1275cc block is taller but the head is still 2.75" deep.

I am not aware of a special bottom hose for the 1275cc engine when fitted to a Minor. You can fit a piece of hose and a stub to join the two parts of the heater return.

[ndevans]

Ok thanks. The thermostat housing does sit at a slightly different angle to the 1098, which means the heater pipe only just clears the studs.
I'll fit a stub pipe to the bottom hose next time I flush it.

Cheers N