Valve springs - single, dual, long or short

There's been some development in valves springs recently. The goal is to eliminate valve bounce. To do that you need to reduce weight and make the spring rate (strength) more linear so the seat pressure is closer to the pressure at full lift. This is achieved by using longer springs as opposed to shorter springs. There is room at the top of the Norton valve stem to move of the collets to make room for a longer spring. The photo below shows a stock valve on the left and a modified valve stem on the right.



Dual springs depend on two weaker springs compared to one stronger spring. And the total spring length of two springs is of course longer. But then the problem is weight. A dual spring setup weighs about twice as much and the retainer must be bigger and heavier than the tiny retainers of a single spring that has a reduced diameter at the top. This is why a single spring that tapers down in diameter at the top can outperform a dual racing spring.

When using a single tapered spring you must use thicker wire to get the same strength as a dual spring. You have to make it longer to avoid too much pressure at full lift or you can have accelerated wear problems on the cam nose. The shorter the spring, the worse it gets.

Beehive springs have been popular for a while now, but the latest hot thing seems to be conical springs, at least in the car world. How about pneumatic springs? Might still be a little early to expect a conversion kit for Nortons, though. It also looks like the technology for digitally controlled electric solenoid valves has advanced to the point that there are development engines running with them at pretty high speeds now. Adding the hardware, as well as all the electrical and computer systems to a Norton might be a bit more difficult. Still, always room for improvement.

Ken

lcrken said:

Beehive springs have been popular for a while now, but the latest hot thing seems to be conical springs, at least in the car world. How about pneumatic springs? Might still be a little early to expect a conversion kit for Nortons, though. It also looks like the technology for digitally controlled electric solenoid valves has advanced to the point that there are development engines running with them at pretty high speeds now. Adding the hardware, as well as all the electrical and computer systems to a Norton might be a bit more difficult. Still, always room for improvement.

Ken

Click to expand...

Yes Pneumatic springs are by far the best for racing but I don't think anyone will want to carry a nitrogen bottle on the street. The available dual conical car springs have way too much pressure for a Norton. If a conical or beehive spring is made short enough to fit stock Norton valves then the spring rate is too high resulting in cam wear - thats the reason for the raised collet position in the photo above - to allow for a longer spring. The available conical springs are stiffer and have a higher spring rate than both the available beehive springs as well as the available dual racing springs.

Jim,

have you checked the beehive springs available from RD? They sell beehive spring kits for vintage Triumphs and some other brands, not listed for Nortons. Their specs for the beehive springs are available here

http://www.rdvalvespring.com/spring-chart.html

KPMI also has beehive springs for some bikes, Harleys, Suzukis, Triumphs, but again, no Nortons.

Some of them have pretty reasonable seat and open pressures.

Ken

To Ken's point,

Luxury hypercar manufacturer Koenigsegg have a sister company called Freevalve, and they are developing a camless Engine.

I have been watching this space for some time as I find it fascinating.

Great video clip here:
https://youtu.be/S3cFfM3r510

We must be able to drive these via solenoids or oil pressure for an electro/hydraulic solution without the need for pneumatics.
Then we can do away with cams, simply dial in the tune you want.
No need for pushrods
No cam chain
No followers going soft or loosing their hardened tips
Much lighter in weight


Now then...
- Comstock and Schmidt Engineering
- New style Fullauto head
- Sold and marketed by cNw


Who wants one?

ME!!!!

gtiller said:

We must be able to drive these via oil pressure for an electro/hydraulic solution without the need for pneumatics.

Click to expand...

Hydraulics!!!!! That would be fun to watch. Here, hold my beer while I .........

A hydraulic drive might be workable with a slow speed engine; maybe a marine diesel.

Dances with Shrapnel said:

gtiller said:

We must be able to drive these via oil pressure for an electro/hydraulic solution without the need for pneumatics.

Click to expand...

Hydraulics!!!!! That would be fun to watch. Here, hold my beer while I .........

A hydraulic drive might be workable with a slow speed engine; maybe a marine diesel.

Click to expand...

Lotus and Renault seem to have made hydraulic valves work a little faster than a marine diesel.

Interesting. All I found for Renualt was conceptual in nature and the only reference stated : "This solution has yet to race or to my knowledge even be tested in a car...."

As for Lotus, I found hydraulic but for research purposes (Lotus's Active Valve Train (AVT) research system) only and one paper (guessing circa 2005 - 2010?) titled "Production AVT Development: Lotus and Eaton's Electrohydraulic Closed-Loop Fully Variable Valve Train System" and coauthored between Eaton Industries and Lotus. It was not clear without reading the whole paper whether it was simulated or if they ever got it to a lab or bench scale. There's also some stuff out there for a Lotus AVT electrohydraulic for research purposes.

If there's more practical applied out there, I am keen to hear about it.

Interesting concept.

"Valvetronic does by using hydraulic fluid running through narrow passages connecting the intake valves and the camshaft so the two can be decoupled."

So the valve is driven open by the cam (through hydraulics) and uses conventional spring to throttle close the valve. Early valve closing events are by carefully timed bleed off of the hydraulics. What kills me is the term "narrow passages"; you would think the fluid friction would eat your lunch.

This is almost an inversion of the air valves concept where you are using an incompressible fluid to open a valve in this case whereas the air valves use a compressible fluid (Nitrogen?) to close a valve (act as a spring).

Almost like a hydraulic lifter where the valves are opened through an incompressible fluid.......but different.

lcrken said:

Jim,

have you checked the beehive springs available from RD? They sell beehive spring kits for vintage Triumphs and some other brands, not listed for Nortons. Their specs for the beehive springs are available here

http://www.rdvalvespring.com/spring-chart.html

KPMI also has beehive springs for some bikes, Harleys, Suzukis, Triumphs, but again, no Nortons.

Some of them have pretty reasonable seat and open pressures.

Ken

Click to expand...

One of the RD beehive springs in the link above is pretty close with 92 lbs seating pressure and that's close to stock Norton seating pressure. But again - this is a longer spring and it needs the collets moved up on the stem to avoid coil bind. Making that spring shorter so it fit stock valves would raise the spring rate and put more wear on the cam.

Rotary valves:

http://www.coatesengine.com/

I have been following this company for about 4years; at one point they had a 350 Chevy at 10,000 RPM...

RoadScholar said:

Rotary valves:

http://www.coatesengine.com/

I have been following this company for about 4years; at one point they had a 350 Chevy at 10,000 RPM...

Click to expand...

Rotary valves are still a dream. Maybe they can bring it home. You should see it in the race industry 1st - but where it is? Sounds very expensive - requiring high precision.

Tend to agree with that sentiment jseng1. Love to see innovation and the rotary valve concept has been around for a long time. Reading Coates Engineering website, there's a dearth of detail on their technology. Reading their copy on news releases comes across to me as "pie in the sky" "big one got away" and then you look at their share price for the last 5 years and .....? I still hope it is a sleeper and they have something there.

There are some interesting concepts presented at Coates regarding combustion chamber and heat and I can see my way through a couple of ways one could achieve variable valve timing with the rotary valve. Would love to see more on the sealing technology as well as flow coefficient profiles.

Agree with the comment about seeing it in racing.

Dances with Shrapnel said:

Tend to agree with that sentiment jseng1. Love to see innovation and the rotary valve concept has been around for a long time. Reading Coates Engineering website, there's a dearth of detail on their technology. Reading their copy on news releases comes across to me as "pie in the sky" "big one got away" and then you look at their share price for the last 5 years and .....? I still hope it is a sleeper and they have something there.

There are some interesting concepts presented at Coates regarding combustion chamber and heat and I can see my way through a couple of ways one could achieve variable valve timing with the rotary valve. Would love to see more on the sealing technology as well as flow coefficient profiles.

Agree with the comment about seeing it in racing.

Click to expand...

Even Velocette was into rotary valves back in the day but gave it up because of carbon related abrasive problems. Its a great idea that has always been just out of reach (so far). The Bristol Centaurus sleeve valve worked well in the Hawker Sea Fury fighter that produced more HP than the poppet valve motors of the time. By the time they get it right everyone will be buying electric cars and scooters.

jseng1 said:

...... By the time they get it right everyone will be buying electric cars and scooters.

Click to expand...

Ya definitely got a point there Jim.