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[Formerlyjeremy]

602
Ah yes - stronger valve springs!

You'll have worked on pre-war engines and some made immediately after - which have tiny valve clearances - then suddenly the clearances shot up form about 3 thou to 10 or 15thou.  The reason was the adoption of silencing curves on the cam profile.  These are recogniseable by the convex surface of the faces of the cam either side of the peak.  The original proponent was Amhurst Villiers - who apparently was brave enough to tell Ettorie Bugatti that by using his camshafts he could rev his engines faster and get more power.

[Wittsend]

I think Ducati might have a word or two to say about desmodronic valve operation 


 

[Formerlyjeremy]

Which is why it hasn't been universally adopted for road engines

[w3526602]

Hi,

I just re-read the earlier replies ....

Surely stronger valve springs will absorb power? But they might compensate/prevent valve crash/bounce at high engine revs (6000+)
in an 850cc Mini ... but at those revs you will need a Duplex (?) timing chain. (Please pardon any errors, it's 56 years since Plod clocked me at 80mph in my bog-standard 1959 Minivan ... slight uphill drag ... 5 passengers. Hang on ... I might have fitted stronger valve springs. ).

Fined £2, and the Beak apologised for the endorsement, said he had no choice.

Did the Granny Rover 80 use the same flywheel? The thought crossed my mind that maybe the 6-pot saloons did not need such a heavy flywheel ... but then uncrossed it, cos they used P3 engines.

Lightening the flywheel may hit you in the "kinetics". Taken to it's extremes, you might need to make the engine scream before lifting the clutch pedal at traffic lights.

I agree that skimming the head will give you most "bang for your bucks", but don't overdo it. LPG is more forgiving than petrol ... I've read that you can take the compression ratio up to 16:1, without pinking. Try a Google for Harold Bates of Brixham (if he is still amongst us). I bought one of his modified Calor regulators (£5),circa 1970, but never fitted it. I gave it to my mate, Gabe (Registrar General of Shipping, now retired) who fitted it onto his Minivan, and got it working.

Gabe had a half share in an Aston Martin DB2, which he sold to buy a Minivan and an engagement ring. He "rolled" the Minivan, and I think he is now on his third (fourth?) wife. In June 1971, I helped Gabe push an MG TC into a shed. Last time I looked in his garage, about two years ago, the newly painted chassis was standing on trestles. The 1964-ish MG 2 Spridget that he fitted with the last of the factory shells, has been under tarpaulin for about 45 years.

602

[Dormy]

Ok , chaps , a skim is what I will go for, there is a chap in Tavistock (Ted Willis )  who can skim it , my neigh bour said the he is expensive but good, I have heard that Turners are also good and do the gas flow bit as well , much more money though, 
Cherrs

You may have the figures you need, but I have attached a pdf. copy of a relevant thread from the old forum. Lots of discussion, but crucially the amount to skim and other pointers to look out for.

HTH
Dormy

[w3526602]

Hi,

Out of interest, is the Land Rove P4 engine the same as  Rover 80 P4 engine? Or are there subtle differences?

Same questions for the P3 6-cylinder engines ... and even the 1997cc 4-cylinder.  I'm sure that my 1953 (?) Rover 60 had more "go" than any S1 that I've met.

I somehow have it in my mind that "Babs" was towed back to Pendine, after her exhumation, behind a 6-cylinder 80". I bet that was fun.

602

PS .. the youngsters in our midst should Google  ... BABS PENDINE IMAGES

PPS ... The last time I visited Pendine beach, in my S1 Bitza, I drove a long way down the beach. On my return I found the bottom of the slipway under water. Not a problem. Are cars still allowed on the sand?