triumphs
[Top] [All Lists]

cams, lifters, etc

To: Triumphs@autox.team.net, FOT@autox.team.net
Subject: cams, lifters, etc
From: "Jack W. Drews" <vinttr4@geneseo.net>
Date: Mon, 28 Nov 2005 20:42:58 -0600
I sent a list of questions about cams and lifters to a friend who 
works in engine engineering at a major diesel engine manufacturing 
company. He talked this over with his friends and following are the 
message and two replies. Nothing earth-shaking, and some we may not 
agree on, but this is what the people who do it for a living say.


>uncle jack

Gary --


The question being discussed on the Triumph list at the moment is 
whether or not it is important to replace the lifters to the same 
lobe after a rebuild.

Sooooooooo............I have a series of questions, and they really 
should be answered by someone who knows, rather than us Trimph owners 
with only opinions:

1. Should old lifters remain with old lobes?
2. Is it ever acceptable to use old lifters on a new cam? How about 
new lifters on an old cam?
3. Is there any reason why an old lifter can't be reground to the 
proper radius and reused?
4. Is Rockwell C hardness the only criteria for successful lifter life?
5. Is there anything wrong with just making the lifters out of good 
steel and heat treating it to, say, Rockwell C 56 - 60?

Jack --

>We believe your cam and lifters are probably made out of chilled iron.
>That is a good thing.  There are very hard carbides in the surface of
>both the cam lobe & lifter surface.  The RC should be around 70.  The
>amount of carbon in each is close to the same which allows them to live
>together.
>
>If you tried to use steel and did HT to RC 60 on the lifters the cam
>would eat them alive in very short order.  Probably what you got
>imported.
>
>If the lobe surface and follower surface looks shinny and smooth, then
>leave them alone.  Match them back up to each other and use them again.
>
>If you have to regrind the lobe, use a new follower.
>
>Always use molybendium disulfide in large amount when rebuilding.
>
>DO not regrind followers, they may not be designed to be flat and even
>if they are it is too easy for all but an expert in this process with
>chilled iron to have micro cracks develop and your in trouble in short
>order.  Buy new ones done right, pay the little extra and have a happy
>valve train.
>
>So to answer your questions.
>
>1) Yes, definitely
>2) NO & NO
>3) Don't do it. 98% chance you can't get it done properly.
>4) Heck no, see my discussion in my previous response.
>5) Everything is wrong with this idea, you will waste time, effort and
>have junk in short order.


uncle jack 


===  This list supported in part by The Vintage Triumph Register
===     http://www.vtr.org



<Prev in Thread] Current Thread [Next in Thread>