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

[Jerry Van Vlack]

FOT, I recently did a good deal of research into cams and lifters for the wet liner engines and I believe the results are accurate for all Triumph in-line engines. Don’t know about the V-8’s in Stags or TR=8’s. My conclusions are that lifters and cams were all ground flat. No radius on lifter edges and no taper on cam lobes. Lifter rotation is accomplished by the lifter bores in the block being offset from the lobes. It sounds simple but what I found was aftermarket cams may or may not be ground flat and I know some suppliers “upgraded” lifters are ground with a radius (confirmed by actual inspection). In the end I had a stock cam reground to D Cam specifications and original lifters reground flat for my hot street engine. I’d advise checking with any aftermarket cam grinder to determine if their lobes are flat or tapered and then ask what lifter to use with their cam. Ask if off set lifter bores have any influence to their systems.
Just my 2 cents worth.
JVV

From: Christian Marx via Fot 
Sent: Monday, July 23, 2018 5:08 AM
To: fot at autox. team. net 
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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