I use Scat ‘cos they’re cheap, but next time I’ll use a Web cam. They’re the things that open the valves – under the rocker covers. Your cam will work with standard 1.1:1 or 1.25:1 rockers for more valve lift.
I choose a web86a and 1,4-1 rockers for my 2165cc. I also bought beehives springs to help reduce head temp. Webcam cams seems to be top notch stuff
Sounds like an engine built for high BHP, an 86A has 290deg duration, a lot for a bus cam, but the capacity should help with the lack of low rev torque. What CR do you have? Beehives springs will keep the valves under control but I don’t see how they will reduce head temps, what’s your reasoning? Yes, Web cams are in a league of their own.
Dual springs rub against each others, generating heat with friction. They are used for years in LS Chevy V8. I like they give an overall lighter valvetrain and don't require to machine guide bosses. It is a first to me, we will see how it works. http://vwparts.aircooled.net/Beehiv...pring-Kit-p/beehives-done-right-street-kt.htm
Hmmm...would dual springs that rubbed together get off the drawing board? They wouldn't get off mine!
As you say Beehive springs are not new, they’ve been used for well over a hundred years and on some regular production engines for over 35 years. Compared to single or double springs and retainers they’re lighter and their big advantage is with very aggressive cams and at very high rpm but they are really overkill for a bus engine with a relatively mild cam and low rpm. The Beehive lower coils become coil bound in operation and I wouldn’t expect the heat generated by double springs touching to be significantly different. I doubt if you’ll notice any difference in head temperatures.
It may be overkill, but there is not really any cons using them. And as it is a bus engine, if I know I can do something to help it running cooler, I would feel wrong not doing it. No regrets after. I build a 1600 with VZ14 and kadrons. Great torquey little engine. I switch cam for a L&G R285 and 1.4 rockers ( French brand from slide performance in Paris. Good stuff.) And dual Weber 40mm. I had to use dual springs and saw a 10° increase in temp. Is it related to springs or something else? I don't know. I'm not a pro, just making my experience.
The only con is the cost but if you had to buy double springs anyway the cost isn’t really significant. But I think you’ve bought very good springs for the wrong reason; I doubt if they’ll reduce the head temperature. Any difference in head temperature would be due to the cam, not the valve springs.
No, there is nowhere near enough contact between the springs to generate a noticeable rise in cylinder head temperature. It's a bit of an aside really, but I'll say it anyway. There are two possible mechanisms for heat generation: one is scuffing contact between springs or coils. This is highly localised to the contact area, which is small, and is very dependent on the load, which has to be very high, and the duration, or frequency of contact as the heat dissipates into the cooler parts of the spring, and any oil that is splashing about. The heat generation is associated with plastic deformation and damage in the contact patch and if this happened in a valve spring it would fail by fatigue in a matter of minutes. The other mechanism is an elastic process that occurs throughout the spring as it extends and compresses. It's called thermoelasticity and the spring cools as it extends and heats up as it is compressed. This is fully reversible and there is no net temperature rise. Oh, and the temperature fluctuations are of the order of 0.1K (or C).
I'm confused now... I read an article in Chevy High Performance about conical springs. That's where I learn what I think I know ... You can find it online, but I'm not allowed to read it for whatever laws. I'll scan the magasine if you want? I saw aircooled.net sold beehives springs kit for the same reasons, and that's why I decide to use them.
Yes, I've seen that explanation, perhaps in a different article, it's a fairly widely held view. If you do a search for valve spring float videos you will see that the springs are terribly wobbly things that don't go up and down neatly. Once they get out of shape any light contact between inner and outer springs will help to dampen the unwanted oscillations, but it's a pretty crude way of doing it. Beehive, conical and all the other different designs are intended to alter the dynamic behaviour to help the springs to do their job at higher rpm and with more aggressive valve accelerations. Part of the problem, I think, is the use of the word friction for both internal, metallurgical hysteresis, and external mechanical contact. A valve coil spring has some frictional contact between the ends of the spring and the retaining cap and also between the spring and the cylinder head. You can see the springs rotate in slow motion videos. There might be a bit of heat generation but I don't believe that it is significant relative to the conducted heat from the head and valve itself. The internal friction inside a coil spring is very small and irrelevant in this context. I can't really see high revs and aggressive cam profiles being an issue with bus engines.
He doesn’t remember the Rockers. It’s been a few months since it was finished. He’ll look for photos, but failing that can take a cover off to check. Said it it was stock then ratio 1.1:1, but if after market it would have been 1.25:1. Sent from my iPhone using Tapatalk
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