Stuart-Turner

Do we have any Stuart-Turner experts out there who could shed some light on the confusing (to me anyway) nomenclature and chronology of the small two-stroke range?

The N does not look that far removed from S-T's first IC engine of 1906, the P3 and P6 are similar, but the P5 looks like a completely different animal - more like a member of the R series! Which ones have overhung cranks and which bulit up jobs, do all have rolling element mains or do the long housings of the earlier engines contain a plain bush? etc etc.

Reply to
Nick H
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"Nick H" wrote (snip):-

That looks like a no then. For what its worth here are my own observations:-

The first engine was made around 1906 according to A-Z, and appears to be a two port engine with the inlet controlled by an automatic valve in the carburettor or gas mixer (I bid on a gas version on ebay a while ago but did not get it, did anyone save the picture). On some versions contacts for trembler coil ignition appear to be inside the crankcase, on others there is a magneto platform on the crankcase cover. I presume it has an overhung crank and long plain grease lubricated main bearing. do you know bore and stroke? Some types also incorporate a belt driven governor mounted directly on the carb. How long did it remain in production for?

The N does not look to far removed from this first engine. Now there is a piston controlled inlet port so the carb has moved through 90 degrees. Crank is still overhung and there is a long single main bearing housing - does this contain a plain bearing or is there a ball race behind the crank? Bore and stroke are 1 3/4" X 2". magneto drives are optionally direct by a follower crank mounted in the crankcase cover (which also sometimes incorporates a governor chamber), or by chain from a sprocket behind the flywheel. The taper for the flywheel is on a separate sleeve which appears to work in a packing gland at the end of the main bearing housing. In the marine version the crankcase cover has a gear driven shaft with an eccentric cam which operates a diaphragm type coolent pump. When was it introduced and again how long did it remain in production.

Both the above engines have the cylinder cast en-bloc with the crankcase but next on the list - the P - has a separate cylinder bolted to a vertically split crankcase which I assume now houses a full width built-up crank supported on each side by a ball race. The P3 (introduced 1921 according to A-Z) again does not look that different from the N but the P5 has an integral water cooled exhaust expansion chamber. P6 is just a larger P5 and P55 and P66 are twin cylinder versions of these (rather remeniscent of the Stella engine). Many options for mag drive, governor etc. Water pump on marine versions now 'banjo' type. Believe these remained in production (or at least available) right up to the end of engine production by S-T.

Smaller R series similar in construction to above. Standardised built it exhaust chamber and extended head over this to give a much squatter looking engine. Again an ever increasing options list. When introduced etc?

Come on then, bearing in mind I have only seen all but two of these types from afar, someone must be able to offer corrections/additional info, maybe even a date or two, to the above.

Reply to
Nick H

Thanks, I have been trying to assimilate the information in the serial number list you sent.

In respect of the N, this confirms what Fairways have told me about marine version, ie. early 30's but I have seen stationary versions dated earlier and the regularity with which they appear in preservation would tend to suggest production numbers were somewhat higher than the 1400 or so serial numbers allocated in the list. Perhaps the list refers only to marine types? The appearance of the R series in 1934 suggests that this took over from the N.

A bit more picture gazing has forced me to revise my ideas about the P series. The P3 (about 1500 made from 1919 to 1928 according to list and therefore never produced as a marine engine if Fairways is right about the

1929 entry date into that market)) has en-bloc cylinder and crankcase, probably therefore overhung crank like N but main bearing is now in crankcase cover with follower crank to drive mag in crankcase. Separate cylinder and vertically split crankcase (and therefore probably full width built-up crank) appear with P4 (1928 on).

All good fun!

Reply to
Nick H

----------------------------------------------------- Info sent off group Mike.H.

Reply to
Mike.H

I'm trying to put together a pictorial recognition album of Stuart Turner engine types on Webshots. I've put up pics of those engines I either own or have owned at

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If owners of other ST engines would like to contribute, I'd be delighted to put their pics in the same place. Please say how the credit should read.

Regards,

Kim Siddorn,

Reply to
J K Siddorn

IMHO. The blue P3 is infact an early two port type, the one labelled 'P series marine??' is an R something (note how head is extended over exhaust chamber) and the final R2 looks like a P something as it has a round head. Could be wrong of course!

I have now found a pic of the gas engine I missed on ebay which I will send and a few others taken at various rallies. Plus I canscan some prints of the R3 I used to own.

Reply to
Nick H

All is revealed (well a little bit anyway).

What looked like a gland nut on the outboard end of the N main bearing housing finally submitted to the ministrations of the soft drift. Not a gland nut at all, it carries an extension upon which the starting sprocket revolves and also retains an LJ20 ball race, old Ransomes and Marles speak for a 6204 - yes metric! So at least one end is thus supported, wonder what happens at the other and what the crankcase sealing arrangements are?

Reply to
Nick H

There are some shots of the Stuart H2M on our web pages if they are of any use.

Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk

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Reply to
Prepair Ltd

I wish I had a better memory! 'Somewhere' I'm sure I have read that the original 1/2HP vertical two-stroke was a 2 port job (and certainly looks it from illustrations, I cant see how a separate inlet passage could have weaved round the transfer from that position). Various iterations of P(3) on the other hand seem to appear with carb on side and back of cyl (if descriptions at rallies are to be believed), though probably side mounted variant (by which I mean perpendicular to crankshaft) is probably offset to allow passage to pass to one side of transfer. I am waiting for Kim to confirm A) that his engine is positively identified as P3 and B) how inlet passage runs.

Does catalogue mention 'N' ? URL please before I die of frustration!

Reply to
Nick H

I have obtained a 1923 Stuart-Turner catalogue on the internet, and the P3 engine is listed there as a 1bhp engine, 2.25" bore 2.5" stroke, but 3-port not two.

There is mention of a redesign but not that the original was a 2-port type.

Peter

-- Peter & Rita Forbes snipped-for-privacy@easynet.co.uk Engine pages for preservation info:

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Reply to
Peter A Forbes

Thanks. That's on the side alriight, I do love the belt drive governor! I take it the cat. is an original you have ppuchased on the internet then? Pat Knight sent me a 1933 'N' catalogue which identifies N2 as stationary engine with governor, N3 as marine engine with cooling water pump and N4 as marine lighting plant with governor and pump. 1930 catalogue page which mike H sent me shows what appears to be basic engine w/o either (N, N1?). Picture of a similar set dated 1926 can be found on Pete Aldous' Thirlow rally page:-

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would seem counter intuitive for P to be introduced before N, but of couse it may have just indicated that the latter was a smaller engine (BxS 1 3/4" x 2"). What does seem certain is that it was not marinised (or marinated as Kim put it!) until the early 1930's. I find it quite frigtening that we are scratching around for information in this way on stuff which is at worst only one generation removed from living memory.

Reply to
Nick H

I've responded off-list, the catalogue is on my desk, not on the internet! :-))

Picture which I have sent you shows the carb on the side of the cylinder, there is no mention of the N model. Catalogue is dated January 1923.

Peter

-- Peter & Rita Forbes snipped-for-privacy@easynet.co.uk Engine pages for preservation info:

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Reply to
Peter A Forbes

As previously announced, I'm putting photos of Stuart Turner devices in a Webshots album in an effort to identify and hopefully provide a chronology for the wide range of Stuart Turner engines, gen sets, pumps etc. See them at

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If you can give better info on an engine illustrated than the current caption, I'd be delighted to include your contribution.

Several people that contribute to this NG have provided photos and occasionally their provenance was shaky. If I am displaying a photo of yours in error, please say and I'll happily credit you or remove it immediately.

Any photos of engines not illustrated would be gratefully received.

Regards,

Kim Siddorn,

Reply to
J K Siddorn

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