Not wishing to hijack Halbe's thread, I thought I'd start a new one.
The McEvoy Minor had the standard cam - if you wanted it to go faster, they would sell you a Zoller blower.
I don't know of any other SV Minors that had uprated cams. At some point, I should talk to some of the cam manufacturers, give then a standard cam and the engine spec. and see if they think a hotter cam would be a good idea. You can get hot cams for Austin Sevens, can't you? And that is SV.
I would have thought that the McEvoy performance could be improved with a better cam, and knowing that William Morris had a penchant for de-tuning his cars to improve reliability. I wonder what cams were fitted to the Skinner Minors - anyone have any info?
Ian, i suspect the only major differences you'd be likely to get away with would be in the timing on the lobes......... as, unlike on ohc engine where the piston dissapear down the bore, the head stays put, not sure how close the valves come as standard, it wouldn;'t be easy to work out....... what with not being able to see it all in situ etc....!
Good point - there isn't much space in the head to have the valves open further - specially when the head is skimmed to increase compression ratio, but I was thinking more about the dwell angles and not valve opening height. I'd need to find a cam expert to sort all this - and that ain't me! Unlike the OHC camshaft, there's plenty of meat on the SV cam, so removing metal to re-profile the lobes shouldn't be a problem.
Hi,
Rather late on this post as have only just joined. As a matter of interest, V. W. Derrington of Kingston produced a range of tuning parts for s.v. morrises both 8's and minors in the late 50's & 60's. Included in their list were High
Lift 40 degree overlap camshafts, aluminium cylinder heads 7.8-1 comp. ratio, twin S U's, four branch exhausts, Scintilla- Vertex magnetos, and if you wanted to be really sporty a "Plastic gear lever knob, mottled brown" for 3 shillings and sixpence!
Has anyone ever seen an alloy head? I have heard from an 8 owner that a 4 branch manifold has boosted his torque and although not much faster he doesn't change gear on hills anymore! Also a 75mph minor is in the morris register and has the 4 branch manifold plus twin SU carbs
I have an alloy head for a Series E morris 8, not a Derrington one though. I have recently refurbished it, welding up damage to waterways, refacing etc and will probably fit it to an engine I am building up with new crank.
I have read somewhere that hotted-up Sevens have their heads planed at an angle. This is to get a 'squish' effect. So the compression can be raised but there is still space for the valves. It appears that this is essentially the same as with a BMC A series head since the valves are all in a line. It can't be done with OHC engines for that reason. It does explain why Austin 7s are so quick. Don't see why it wouldn't work with a SV Minor engine.
David Brown told me once that he has an alloy head for a SV Minor. So I think they were available. Incidentally, David recently re-joined the Register.
On the subject of special heads; I have seen 1930s 'Alta' heads for both the minor and the morris 8. The ones I have seen are all cast iron.
I've no idea if they are any good though. There were loads of different heads available for the Austin 7 but most owners today still seem to prefer the standard 'ruby' head. From memory, isn't the 1934 minor head meant to be better than the earlier sv. heads?
There were two standard heads for the SV Minor. The 1931 season cars had a head with a detachable water inlet, which apparently starved the rear cylinders of water, so it was re-designed as a single unit with a water inlet that sloped all the way to the back of the head for better cooling of the rear cylinders. Other than that, I think the combustion chambers were identical.
I thought I had read somewhere that the 1934 head was was of higher compression but I'm probably getting confused.
There's lots of mention of different cylinder heads in this article including: standard 'copperized', 'silvertop' and an alloy 'alta' used on a trials minor.
Reading the automobile article of the Sullivan specials, it states 'The camshaft featured a new high-lift long opening-profile.'
There's lots more tuning detail int he article. It also states that stronger components from a 'Wolseley Whippet' were used in the rear axle. Presumably it means 'Wolseley Wasp' which had four star diffs.
Like the McEvoy, the Sullivans were Jenson bodied and supercharged and capable of 92mph! (with reduced 750cc capacity)
Driver reports from several sources have suggested to me that the 34 engine was quicker even though it has the same parts as the 33. One suggestion was a copper coating but thats probably hearsay! I have been reading parts books and I still don't get the different tappet clearances as none of the valve gear changed from 31-34, although the tappet cover did! presumably to show the new tighter clearances? It coincided with the head and manifold change so presumably they ran cooler allowing for closer tappets. Mine certainly run hot even with the later head and the first sv engine changed design after the 1st few 1,000 were built gaining a stronger block and bigger water inlet... as was the diff, presumably upgraded a bit too, from the outside it only has an extra side webb, maybe had a lower ratio before? I only recently discovered the £100 minor had a body 2 inches narrower than the later ones up to 34...
And yes, I must get out more!!!
I am intrigued by this thread, especially the comments about valve clearance when the head is skimmed. The part of the combustion chamber above the valve is 11mm above the block surface and the valve lift is around 6mm. The Ten Six Special has a hig lift cam so I wonder what the clearance is on that.
I am not convinced that an aluminium head can make much difference to performance unless the combustion chamber shape is changed. It will conduct heat more rapidly that iron so it might run cooler but that could reduce the thermal efficiency. The same must be said for copper plating which Jack Bond believe improved performance. He was certainly right about the Scintilla coil, skimming the head and larger carburettor so he may have been right about that as well.
As for camshaft timing, Morris used timings that gave the best performance throughout the range so that gear changing is minimised. I remember a 1932 two seater on the Mannekin Pis which was on the rally with two men in it - I always wondered where they carried their luggage. The owner claimed that he went everywhere in top, even roundabouts which it would take at 10mph.
I always thought that supercharged engines for the road kept the standard camshaft timing and compression ratio for the same reason. You might ask David Baldock if he was able to find out the timing for the Red Minor engine that he knows about. I will also have a look at the notes that Titch Allen compiled when he created the replica of the supercharged Triumph twin that we blew up at Montlhery this year. He certainly found Ivan Wicksteed's notes from the original build.
These days I am more interested in motorcycles as my 490cc Norton produces 50% more horsepower than the 848 Minor which is the wrong way round!
Last edited by ayf395 on Sat Nov 12, 2011 3:00 pm, edited 1 time in total.
