Not quite the same thing, but we'd do it with our old pushrod motorbikes when I was a lad. Deliberately misaligning the camshaft by one tooth gave you a bit more top end or bottom end, depending on what sort of mood you were in. Of course, you could probably get a bus in between valve and piston in those days. It wasn't considered safe to leave it out for too long, though.
Certainly it did pull slightly better from low engine speed, and depending on your driving style it might well have been more economical, I certainly believed him (20 years then, now I have known him for 45 years), his complaint was that he could not use third to such a low speed after the belt change. He soon got used to it. I am more of a redline sort of driver so I preferred it to have power nearer the top end.
We used to do that to 650 Bonnevilles, you could get them quite peaky without immediate ill effect using best quality petrol.
You probably know about the E3134 cams, then :-) I still have an old T100 Daytona, but it doesn't get out much.
That was the ones. A friend of mine still restores and repairs them (and others) for a living.
En el artículo , Dan S. MacAbre escribió:
:)
Because of pinking/knocking? Doesn't that cause premature wear?
En el artículo , MrCheerful escribió:
Thanks. Interesting to hear those sort of things from the coal face, so to speak :)
Yes, and you had to keep it revving to avoid that, so you couldn't really relax. And in the back of your mind, you're thinking about burning away your valve seats.
It was when trying to set up my 650 Triumph race engine in the late sixties that I realised that cam timing is critical to performance, and manufacturers' tolerances were crap.
In order to get the best from an E3134 cam, you needed to use the gear wheels that have three keyways cut, each allowing slightly different timing. You tried each position on both the inlet and exhaust cam, and selected the keyway closest to correct. You could still end up with it up to five degrees out!
In conjunction with my toolmaker friend, I came up with a better. way. I used normal gear wheels, assembled the engine leaving out the keys but holding everything in the correct position with an assortment of clamps, and marked the keyway position away from the existing one. My friend then machine a new keyway for me.
I did lots of other work to the valve-gear in particular; something must have worked because although my Triton was un-faired and I ran on open pipe (no megaphones), I once recorded a speed of 138mph on the Norwich straight at Snetterton - the fastest speed recorded at that meeting.
Of course, altering valve timing alters engine characteristics - that's why VVT is being used more and more.
Chris
I don't know anyone who bought them, but they were semi-legendary when I was a lad. But when the Trident appeared, all those that were interested in speed gave up polishing their inlet tracts and valves and just took out the required loans.
We were lucky enough to live near an ICI, so we could generally find someone's dad who could get just about anything done in the machine shops. Even up to getting a frame stove-enamelled. Unlimited supply of solvents, too.
I had a little Tiger Cub, of all things, that I absolutely loved. Dead easy to throw around, and would climb up anything. It was most happy with a bit of chrome exhaust pipe scrapped off something else, just flattened at the end. It almost flew with that on :-)
I already mentioned I've a Daytona, but with only four gears, it all seems a bit hectic these days. Now I wish it was a Thunderbird, and I could just plod around on it :-)
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