[Fot] Do(o)med or flat lifters?

vfracing at aol.com vfracing at aol.com
Tue Jul 24 05:59:13 MDT 2018 

Check out the Triumph cam discussion from Tilden Technologies: see http://www.tildentechnologies.com/Cams/


Phil Gott


vfracing at aol.com




-----Original Message-----
From: pegandbobm--- via Fot <fot at autox.team.net>
To: rkrantz77 <rkrantz77 at comcast.net>; fot <fot at autox.team.net>; Fubog1 <Fubog1 at aol.com>; tr4racing <tr4racing at googlemail.com>
Sent: Mon, Jul 23, 2018 8:24 pm
Subject: Re: [Fot] Do(o)med or flat lifters?


Not an expert but I WILL GUARANTEE the lifters in my air cooled German made VW Formula Vee engine have a slight radius/angle.  I check this before each rebuild to ensure they have not flatten.   Pre-Trump I think Germany was still considered part of Europe>
 Bob   



-----Original Message-----
From: Ron KRANTZ via Fot <fot at autox.team.net>
To: Christian Marx via Fot <fot at autox.team.net>; Fubog1 at aol. com <Fubog1 at aol.com>; Christian Marx <tr4racing at googlemail.com>
Sent: Mon, Jul 23, 2018 1:46 pm
Subject: Re: [Fot] Do(o)med or flat lifters?



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
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