Odd things about the earliest OHC engines

[Sam Christie]

I have noticed some odd details in the earliest pictures of Vintage Minor engines and displaying my ignorance I would like to know more about the following -

In early pictures of the left hand side of the engine block there is a round raised area on the side with three screw heads visible. What was this for?

On early crankshafts the flange seems to have been a parallel rather than a taper fit. If this was so, why ? Did this arrangement prove troublesome ?

Early engines seem to have had an unusual SU carburetter . Why the elaborate unfamiliar float chamber and why was it replaced ?

Early engines (or was it more general) seem to have had a sump gasket which included a wire gauze sheet. Why do we never hear of this feature any more ?

[ian judd]

I tried one of the gauze sump gasket/strainer things. Unfortunately it tended to clog up rather easily and the oil would stay on top rather than dripping into the sump. Bad enough with modern oil, I should think it would have been much worse with
old-fashioned oils.

Ian

[Ken Martin]

Hi Sam
The early - porbably pre-production engines - had the feature you mention on the side. The early carb with the integral annular float chamber was apparently designed for the Minor, but was unsuccessful and the normal type replaced it early on. The gauze fillter was also an early feature - soon discarded. The parallel flywheel shank to the flywheel was used on the 1928 and 1929 cars with small dynamos - up to about October 29. Someone will no doubt have the engine numbers when theese cahnges took place!
Ken

[Ken Martin]

To enlarge slightly and far from comprehensively on my last rather hasty and inadequate posting: the early cars had an oil filter and so I assume that apart from the additional cost of the unecessary gauze above the sump - Ian's reasoning is sound: it got clogged up and was without real purpose - indeed a hindrance to oil flow.

The hole in the side of the block was perhaps for inspection purposes. Contemporary pictures show that there was one on each side of the cylinder block. The one under the carb certainly had a removable plate. Cost probably caused the change: first to change the casting such that the hole was sealed with the shape retained and then removal of the feature altogether.

I have one of the early type carbs although I have not used it on my 1930 car wich has a flat topped float chamber. I can't see an obvious design fault but on the other hand why not use the standard proven arrangement that SU had used for some years? I assume that the problem was leakage from the float chamber. Tony Gamble's 1928 saloon still uses one of these carbs...

Perhaps there were some problems with flywheels not being addequately secured with a parallel shank. The later conical type work much better due to wedge action although I have heard of fitting porblems with this type as well. If this occurs the two surfaces can be ground togther to fit using some light paste. Conversely the two parts are sometimes very hard to separate!
Ken

[DF9053]

The early cylinder heads had the oil pipe coming out of the side of the oil drain casting at the front, this was subsequently moved to the under side of the casting.

[Sam Christie]

The photo is very interesting - I think I have seen this one in a road report at some stage but I missed the detail. By the way a friend in Wales said that the horn was mounted on the rocker cover on very early M-types and this one has a couple of apparently redundant screws on the cover though the horn is mounted beside the petrol tank. There seems to be quite a wide variation in horn types and mounting positions on earlier cars.

[Colin]

I seem to have a problem with one of the "Odd Things about the Earliest OHC Engines"
The parallel shank is very simple to produce compared to a tapered one. the flywheel is actually very difficult to remove from this crank shaft. The tapered ones will come off with a puller and a bloody good whack. The parallel one on mine seemed to be forever clinging to the driveshaft. Even my one which was split open along the keyway was a b*tch.
I still need to replace it though, so please! if anyone has one or maybe knows someone who has a "Rear main Journal Flange" (parallel type) i would be more than just grateful
Thanks
Colin

[Ian Grace]

Two people to try - Tony Gamble and Rodney Griffin. Contact details in membership list in the the Members' Area or e-mail me.

[Tony Gamble]

Unfortunately I am looking for one too !!

See my advert on the http://www.prewarminor.com website

Do I hear "hens teeth" !

Tony G

[Ian Grace]

Hmmm. Do I hear 'batch production'?! It shouldn't be a difficult item to make. Colin, why don't you get in touch with someone like Paul Rogers, who I'm sure would be happy to help out. We have to have you back on the road by the LC Welsh. In the meantime, I'll put an urgent ad for two flanges on the website.

[Simon]

How about a bit of lateral thinking here. Consider converting the parallel end of the crank to a taper end, recutting the keyway and using a later taper flange. There must surely be a few of those about from all the Minors and M Types that have been fitted with modern cranks.
Before doing anything do not forget to have any crank that one is proposing to reuse CRACK TESTED. My 29 Minor has a parallel flange crank so I need to retain the flange that came with it.

[Simon]

From the 1st July 1931 official Morris spare parts list the changeover from parallel to taper fixing on the crankshaft flange is Engine No U12326 .

[Ian Grace]

This and more info on changes and chassis numbers can be found on the website at

http://www.vintageminor.co.uk/tech/index.htm

[Ian Grace]

This unusual oil drain housing was sent to me by Gabriel Ohman this week - it has four BA threaded holes on the underside plus the remains of a card gasket - so presumably had some sort of seal attached below. Has anyone ever seen anthing like it? Is this a feature of early engines? I don't have a standard drain gallery here to check at present, so can anyone spot any other differences?

[Tony Gamble]

Ian

Here is a photo of one from my bench. Quite different !

oildrainhousing2.JPG (31.96 KiB) Viewed 2923 times

Tony G