I do have original stanpart triumph Tr4 lifters which I've bought years
back . They are flat no crest.
So my thought is that the factory wants them flat.
I say if a lifter fails is caused by a lack of lubrication. If two curved
surface run each other the contact patch should be as large as possible to
create an oil film on which the lifter can surf. Every surfer knows that a
convex surfboard has less lift than a flat one. Concave doesn't work for
lifters for other reasons.
The job is to maximize the surface and induce some rotation for even wear.
So think these nice lifters failed as they were running on the tip.
Cheers
Chris
Ron KRANTZ <rkrantz77 at comcast.net> schrieb am Mo., 23. Juli 2018, 18:33:
> The reason for a slight angel on the lifter is to keep it from digging
> into the ramp on the cam lobe due to an aggressive acceleration design.
> Typical American (cannot say what European mfg. does) lifters have
> approximately a 60 inch radius. I even have an additional edge radius put
> on the lifters. The cam lobes have a slight taper side to side for
> rotating the lifter. Lift on a cam is limited by base circle radius which
> in turn is limited by cam bearing diameter. Then you get into duration and
> how fast you can get the valve open. All the Triumph "flat" tappets I have
> ever seen have a slight radius. The rules say you must retain the same
> type (flat, roller, mushroom) lifter as stock. My question is "how flat is
> flat". Rule does not say the lifter has to rotate. If a lifter has a 0.75
> inch radius across the lifter diameter and no taper on the cam lobe,you can
> keep the lifter from rotating and accelerate the cam opening very fast.
> Think about that.
>
> On July 23, 2018 at 8:46 AM Christian Marx via Fot <fot at autox.team.net>
> wrote:
>
> This may be true for American engines.
>
> All European engines have no angel in the Cam shaft. And all the tappets,
> lifters, rollers, are flat. Dead flat. No light with an edge on it.
>
> So maybe this is just an American thing?
>
>
> Cheers Chris
>
> fubog1 < fubog1 at aol.com> schrieb am Mo., 23. Juli 2018, 15:40:
>
> This is well covered in many engine-building books & I've discussed it at
> length with several camshaft engineers over the years.
> It's my understanding that the lobe should have a very slight angle ground
> in, and the "flat" tappet really isn't, it's very slightly convex.
> This will give it rotation, if it doesn't rotate it will wear.
> There could also be spring pressure or lubrication issues?
> In any case I would discuss it with the tappet supplier before doing
> anything, at the least make sure that they are sufficiently hard to begin
> with and can be reground.
>
> Glen
>
>
>
> -----Original Message-----
> From: Christian Marx via Fot < fot at autox.team.net>
> To: fot at autox. team. net < fot at autox.team.net>
> Sent: Mon, Jul 23, 2018 6:04 am
> Subject: [Fot] Do(o)med or flat lifters?
>
> In the past we had this discussion.
> I've bought some high quality lifters from USA, made from tool steel I
> suppose. 400$ they've cost..... and started to fail. On 3 of them, the very
> center does show e few pittings. Also visible that only a small part of the
> Cam is used.. The cam is okay
>
>
> The machine shop will grind the lifters dead flat, as they should be, they
> say.
>
> Cheers
> Chris
>
> Am 18.07.2018 02:12 schrieb "fubog1 via Fot" < fot at autox.team.net>:
>
> Yes, lacking access to a Cam Doc, you can use a set of V or bearing
> blocks, a degree wheel, dial indicator, and a bit of time, checked at 5 cam
> degrees, works fine.
> I'm still old school though, I plot them out on graph paper!
> That will give you the lobe profile but most folks don't have the full
> specs on the cam, usually just advertised lift and duration.
> Since the tip of the lobe usually starts to go away first, a simple lift
> measurement will reveal the worst, best done with a dial indicator cuz some
> (cheap) cams are ground on different base circles.
> Generally, ramp wear is unusual if the tip is still OK, although there can
> be exceptions.
>
> Glen.
>
>
>
>
> -----Original Message-----
> From: timmmurphh < timmmurphh at gmail.com>
> To: 'fubog1' < fubog1 at aol.com>; rbtr3a < rbtr3a at cox.net>
> Sent: Tue, Jul 17, 2018 12:38 pm
> Subject: RE: [Fot] Cams
>
> By degreeing the cam using increments of 10 crankshaft degrees (5 camshaft
> degrees) and then plotting the results in Excel, it is possible to get a
> very accurate picture of the profile of the cam.
>
> I?ve attached a spreadsheet showing an intake and exhaust lobe comparison
> two years apart of our Kastner G3 cam for reference.
>
> Tim Murphy
> #317 TR4
>
> *From:* Fot <fot- bounces at autox.team.net> *On Behalf Of *fubog1 via Fot
> *Sent:* Monday, July 16, 2018 6:31 AM
> *To:* rbtr3a at cox.net; fot at autox.team.net
> *Subject:* Re: [Fot] Cams
>
> Generally any obvious wear or pitting would make it unserviceable, but the
> wear isn't always so obvious.
> You can measure the lift and compare to spec, that will show any worn
> lobes, but the best way is to find someone who has a "cam doctor". It's a
> machine that sets it up and measures the complete profile.
> Usually if there is anything apparent that suggests that there may be
> problems, there are...
>
> Glen
>
>
> -----Original Message-----
> From: rbtr3a--- via Fot <fot at autox.team.net>
> To: fot <fot at autox.team.net>
> Sent: Sun, Jul 15, 2018 6:47 pm
> Subject: [Fot] Cams
>
> How do I determine if a cam is good or bad. If there are any marks on it
> does that make it bad. I do know that two of the lifters has pitting on the
> surface.
>
> Ronnie
> _______________________________________________
> fot at autox.team.net
>
> http://www.fot-racing.com
>
> Donate: http://www.team.net/donate.html
> Archive: http://www.team.net/pipermail/fot
> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/fot/fubog1 at aol.com
>
> _______________________________________________
> fot at autox.team.net
>
> http://www.fot-racing.com
>
> Donate: http://www.team.net/donate.html
> Archive: http://www.team.net/pipermail/fot
> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/fot/tr4racing at googlemail.com
>
>
>
> _______________________________________________
> fot at autox.team.net
>
> http://www.fot-racing.com
>
> Donate: http://www.team.net/donate.html
> Archive: http://www.team.net/pipermail/fot
> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/fot/fubog1 at aol.com
>
>
> _______________________________________________
> fot at autox.team.net
>
> http://www.fot-racing.com
>
> Donate: http://www.team.net/donate.html
> Archive: http://www.team.net/pipermail/fot
> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/fot/rkrantz77 at comcast.net
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://autox.team.net/pipermail/fot/attachments/20180723/15ca8e37/attachment.html>
|