Joined: Jun 2019 Posts: 37 Threads: 0
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Location: Ilkley
Car type: Ulster 1930
I have just retrieved from the loft my 1931 edition of Ricardo's The High Speed Internal-Combustion Engine . This was required reading
as an apprentice in the engine design and development section of a group of engineering companies.
In the chapter ' Influence of Form of Combustion Chamber ' Ricardo's Shock Absorber ' head is described in detail . This is similar to the combustion chamber form in the aluminium heads currently available.
The '37 A7 head has the Ricardo ' Turbulent Head' an earlier and much simpler design and similarly described in detail , with the comment
'licenses have been granted to engine manufacturers' .
Its still quite an informative read for anyone with an interest in I/C engines and strangely nothing is really new !
As an aside , I found my Whatmough aluminium head complete with patent plate at a subsidiary company some time later.
Geoff
Joined: Aug 2017 Posts: 172 Threads: 1
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Location: Richmond, Texas, USA
My father was an advocate of the Whatmough-Hewitt head until at on race meeting the roof of the combustion chamber of one cylinder, modified for oversize inlet and high-lift, fell in and stopped the plot.
From then on Simplicity wore a slightly modified 9E head, with some measure of success.
Joined: Aug 2017 Posts: 1,256 Threads: 32
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Location: Cheshire
Car type: Race Ulster, 1926 Special, 1927 Chummy, 1930 Box
Interesting thing about Whatmough and Ricardo is that they came up with very different head shapes from exactly the same reasoning. Apart from Ricardo don’t forget the real experts on tuning side valves were Harley Davidson. There’s a load of interesting stuff on the internet, together with model A Ford tuning.
Alan Fairless
Joined: Aug 2017 Posts: 124 Threads: 15
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Location: East Sussex
Thanks everyone for your responses so far. Am I correct in thinking then that a “Ricardo” head like the ones that Dave sells are/were, after market items designed to improve performance rather than being fitted to production cars? Alan
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
Hi geoffharrison
Ricardos book is a good read free of the fancy calculus and the like which places so many modern texts beyond the casual amateur. By modern standards the early rules of thumb for sizing componets are somewhat amusing. The several editions vary considerably and the later are more an account of his work, esp the peculiarly UK notion of the single sleeve engine. Unfortunately the BA types who control libraries dump such books so becoming hard to find. Ricardos auto biagraphy published under a couple of titles is also very readable.
Before learning there was an afteremrket one with the name I always referred to the 37 head as Ricardo as it so obviously is.
On the topic of head breathing I often wonder if the 4.9:1 RN produces more bhp than the more constricted 5.2 RP as original road tests and current owners seem to report better performance despite updraught carb.
Joined: Aug 2017 Posts: 605 Threads: 18
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Location: Sheffield South Yorks
Car type: 1932 RN saloon
Someone mentioned (Chris KC I think) compression ratio of Speedex head as being roughly 10.5 to 1.
I have been measuring combustion chamber volume on my Speedex head which is 35cc with spark plug fitted. This with a standard HC gasket 0.025” (used, therefore already squashed) and assuming pistons at TDC are level with top of cyl block, (they are below in fact) and a +.060” oversize bore gives less than 6.5 comp ratio.
Cheers,
Dave.
Joined: Aug 2017 Posts: 3,210 Threads: 100
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Might be true of a new one Dave, I think mine had been round the block a few times...
Joined: Aug 2017 Posts: 605 Threads: 18
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Location: Sheffield South Yorks
Car type: 1932 RN saloon
Chris,
Yes, I bought mine from Tony Betts a few years ago. He had 2 at the time, one of which looked as though it had been heavily reduced in thickness and the other with a larger combustion chamber I purchased from him. I am pleased with it as it doesn’t cause the plugs to oil up. I know I should get the block rebored but later perhaps!
Cheers,
Dave.
Joined: Oct 2019 Posts: 41 Threads: 9
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Location: R o. Ireland
Car type: '34 RP ,'30 RF
Been following this sand another thread on alloy Heads
I remember that sometime in the late '80's the A7CA magazine ran a couple of features on alloy heads.
Over the years I've run two types of Speedex heads -the earlier one on an RP saloon and the other on a Speedex special - both worked OK but both were on 'road' cars.
Currently on my shelf I have an ALTA head dated 1931 which has steel inserts converting it to 14mm plugs
And a Supalloy H/C one.- might fit this one to the RP.
Another one I have is a bit of a mystery to me:
Back in the mists of time I acquired ( I seem to recall from Simon College) a PARAMOUNT alloy head which appears to be a low compression head -exactly as a chummy type with pear shape water outlet and early pattern combustion chambers. It has, however, 14mm plug threads so probably post war. Anyone know anything about these Paramount heads -do many exist and what/why/ when etc?
