Finger Followers
Discussion
Useful link from the Tuscan list today. I've never been quite sure what the finger followers are, so here's a neat animation:
www.torrington.com/innovations/automotive/fingerinitial.html
www.torrington.com/innovations/automotive/fingerinitial.html
Interesting the line that says:
"The replacement of former sliding follower designs with Torrington rolling technology eliminates the constant metal-to-metal sliding contact that used to be a source of valve train noise. In one production DOHC engine, roller finger followers have reduced noise level 2 - 3 dB. "
The SpeedSix engine is probably one of the noisiest, clatteriest engines i've ever heard!!!
-andy-
"The replacement of former sliding follower designs with Torrington rolling technology eliminates the constant metal-to-metal sliding contact that used to be a source of valve train noise. In one production DOHC engine, roller finger followers have reduced noise level 2 - 3 dB. "
The SpeedSix engine is probably one of the noisiest, clatteriest engines i've ever heard!!!
-andy-
quote:
Useful link from the Tuscan list today. I've never been quite sure what the finger followers are, so here's a neat animation:
www.torrington.com/innovations/automotive/fingerinitial.html
Oi - I posted that on the tuscan list years ago... keep up at the back. And they're nothing like the ones actually used in the Sp6 - they don't have rollers for starters - just a hardened pad the cam grinds against - same at the valve end. Yuck.
I was wracking my brains recently where I had seen a picture of a finger follower before - and found dannylt's posting on the Tuscan egroup and reposted it.
It looks like Torrington do roller followers - but the speed 6 has slider followers. I don't know a reason why other than to save money.
The obvious wear point is the contact between the cam and the
follower. (I'm told the shim's go between the valve and the follower btw).
I think this means, that because the valve must be closed fully to
get good compression, there is always a "small" gap between the cam
and the follower at some point. This would result in some percussion -
and as the metal may expand slightly when it warms up, I would
expect the gap to be bigger when the engine is cold.
Therefore you would tend to get a rattly top end when cold which
should quieten up the car warms up. It also means the contact area
between the cam and the follower has to stay within tolerance between tappet adjustements - 12000 miles. The top end might get slightly more noisy leading up to this.
So what can go wrong :
the top end isn't lubricated properly - the wear is quicker -
resulting in a noisier top end sooner and a tappet adjustment
the finger breaks - this would mean a large bang and the engine
would sound like a bag of bolts
the contact areas are not hard enough and wear quicker, resulting
in a noise getting louder as the gap gets bigger and the percussion
gets louder
Then if a shim fell off, apart from the noise of the metal floating
about, the valve would also close up (not open as much) leading
poorer running.
I think the running in most importantly beds in the
pistons and the bottom end. The most wear at the top end would seem
to occur when running the engine cold. That would suggest, again,
that the running in period does not affect the top end so much. It's
just as well all Tuscan drivers carefully bring the engine up to
temperature before using > 2500 revs (as explained in the manual).
Cheers,
Andy.
It looks like Torrington do roller followers - but the speed 6 has slider followers. I don't know a reason why other than to save money.
The obvious wear point is the contact between the cam and the
follower. (I'm told the shim's go between the valve and the follower btw).
I think this means, that because the valve must be closed fully to
get good compression, there is always a "small" gap between the cam
and the follower at some point. This would result in some percussion -
and as the metal may expand slightly when it warms up, I would
expect the gap to be bigger when the engine is cold.
Therefore you would tend to get a rattly top end when cold which
should quieten up the car warms up. It also means the contact area
between the cam and the follower has to stay within tolerance between tappet adjustements - 12000 miles. The top end might get slightly more noisy leading up to this.
So what can go wrong :
the top end isn't lubricated properly - the wear is quicker -
resulting in a noisier top end sooner and a tappet adjustment
the finger breaks - this would mean a large bang and the engine
would sound like a bag of bolts
the contact areas are not hard enough and wear quicker, resulting
in a noise getting louder as the gap gets bigger and the percussion
gets louder
Then if a shim fell off, apart from the noise of the metal floating
about, the valve would also close up (not open as much) leading
poorer running.
I think the running in most importantly beds in the
pistons and the bottom end. The most wear at the top end would seem
to occur when running the engine cold. That would suggest, again,
that the running in period does not affect the top end so much. It's
just as well all Tuscan drivers carefully bring the engine up to
temperature before using > 2500 revs (as explained in the manual).
Cheers,
Andy.
quote:
I don't see why not - but I imagine it would be expensive for what you get (a quieter top end). Don't forget, slider followers should (do) work as well!
Indeed, at least 90% of cars that have followers will be using sliding ones. The rolling followers offer reduced noise and marginally reduced friction/wear at the cost of increased complexity and manufacturing cost.
There should be no problems with sliding followers as long as top end lubrication is okay. Now I've heard of people complaining about oil pressure dropping below 10psi at idle. Could have something to do with it.
there is a problem going to roller followers with no other mods, you don't get the same valve lift / acceleration for any given cam grind. the cam lobe swipes across the std follower surface so increasing the effective follower ratio as the lobe moves towards / away from the pivot point. With the roller version the effective contact point is fixed relative to the pivot of the follower so to maintain the same valve lift etc you need to regrind the cam lobes with a compensating profile. the total valve opening duration remains the same for both set-ups, it's everything else that changes ... bummer.
Been keeping an eye on the oil pressure all day today. Sitting in traffic with the oil temp reaching high 80s/low 90s... oil pressure still no lower than 16psi.
One thing I thought, i'm still within 6000 miles and so not running Mobil1 in the engine yet. With that in mind, could the thicker oil they use up to this point maybe result in the higher oil pressure at idle.
-andy-
One thing I thought, i'm still within 6000 miles and so not running Mobil1 in the engine yet. With that in mind, could the thicker oil they use up to this point maybe result in the higher oil pressure at idle.
-andy-
Can't remember what levels the manual says but 8psi seems VERY LOW. I would be questioning the oil system at those levels. When mine is fully up to temp including heatsoaked oil it will never drop into single figeres.
I would suggest a more normal figere of 12-18psi.
IF YOU ARE CONCERNED RING YOUR DEALER OR THE FACTORY AND ASK THEM WHAT IT THE RECOMMENDED NORMAL.
I would suggest a more normal figere of 12-18psi.
IF YOU ARE CONCERNED RING YOUR DEALER OR THE FACTORY AND ASK THEM WHAT IT THE RECOMMENDED NORMAL.
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