[Healeys] Denis Welch Tappets Again

[Michael MacLean]

Mirek,
     I am kind of at a disadvantage.  The engine I have is assembled from
parts from many engines.  Nothing is original to anything in the engine.
The head came off a 100M that had a bent valve, so there is one valve guide
that is larger in diameter than the other seven.  Even the two rear main
caps are from another engine.  I did have it line bored.  Where I would get
an original cam I don't know.  The best I can do is have the cam lobes
hardened by the people that ground it for me. (they were not hardened when
it was ground originally) and use the OEM tappets I have on order.  After
that, carefully break it in. I appreciate your input.
Mike MacLean

On Wed, May 24, 2023 at 6:42 AM <m.g.sharp at sympatico.ca> wrote:

> Mike, I am really no expert on this, but having had cam/tappet issues with
> my ’56 BSA motorcycle (same technology as a Healey) in the past I did look
> into it about 18 years ago, and Mike Salter and I had a long discussion
> about cams and tappets when we did my BT7 engine a few years ago.  One
> thing I was told by a bike engine builder I trust is that the hardness of
> the cam lobes and the tappets should be the same.  If they are mis-matched,
> rapid wear can occur.  It *may* (I am speculating) not be so much that
> the cam or the tappets are not hardened properly, it is just that they are
> hardened *differently*.   I eventually ordered the motorcycle cam and
> tappets from the same source with the promise that they were made to work
> together.  That seemed to work on the bike.  I think buying a cam and
> tappets from different sources is not the best idea.
>
>
>
> With my BT7, we were lucky, as even after over 100.000 miles, the cam had
> virtually no wear, and only one tappet showed signs of wear, so that was
> replaced with an good used original one that Mike had.  So my original cam
> and 11 of the tappets were re-used (with the tappets put back in the same
> order as they came out).  Only 2000 miles on the engine, so jury is still
> out on that, but I just checked  the tappet clearances and so far no signs
> of wear.  I am surprised that Ahead4Healeys actually have NOS tappets.  Are
> you sure that they are not re-manufactured?  If they are actually NOS, I
> would be inclined to use them and find a good original cam to use with them
> (assuming the original one you have is too worn to re-use).  The fact that
> my original parts were fine after 100,000 miles are a testament to the
> quality of the original parts.  Mind you, I am only the second owner of the
> car, and I knew  the first owner well, and we both performed regular
> maintenance; that is key to longevity.
>
>
>
> Also, I don’t know what you are doing with valve springs and rocker gear.
> Remember whenever you deviate from stock, there are repercussions.  Higher
> lift cams, increased spring pressure, etc., all excerpt additional stresses
> on cam lobes and tappets.
>
>
>
> Good luck with it – these are hard decisions when re-building and there is
> so much mythology about cams and tappets to sift through.  My personal
> approach is use original parts whenever I can – they work and they last!
>
>
>
> Cheers, Mirek
>
>
>
> *From:* Healeys <healeys-bounces at autox.team.net> *On Behalf Of *Michael
> MacLean
> *Sent:* Wednesday, May 24, 2023 8:42 AM
> *To:* Ahealey help <healeys at autox.team.net>
> *Subject:* [Healeys] Denis Welch Tappets Again
>
>
>
> As I get closer to starting my 100 engine I have yet to replace the
> modified Denis Welch tappets like a list member suggested I do.  I got
> nervous, so I ordered a set of NOS tappets from Ahead4Healeys to swap with
> the installed Welch tappets recently.  Now, searching the archives, I  find
> someone had problems with NOS lifters after 6000 miles. Ruined a cam and
> the lifters.  So, what am I supposed to do now?  Should I just buy
> aftermarket tappets?  Are the aftermarket tappets hardened correctly?  Why
> wouldn't the NOS tappets be hardened right?  I don't want to replace the
> cam after I get this thing running.
>
> Mike MacLean
>
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