[Healeys] Denis Welch Tappets Again

[Michael MacLean]

Just got off the phone with David Anton of APT.  According to David the
original cams in big Healey engines are hardened all the way through.
Re-grinding a profile in an old cam will not be a problem with hardness.
In fact, As David explained to me, typically tappets are supposed to be 5
points harder than the cam surface.  He told me to just run it.  David also
said any damage to the cam or lifters is done in that first 20 minutes of
break in. Any subsequent damage would show up in filings in the oil and
having to keep re-adjusting the rockers.  I guess a magnetic drain plug is
next to add to my parts order.  Kind of sorry I started this thread, but it
was quite an education.  When I started researching timing the cam for
reinstallation my head hurt from all the variables and figuring to be
done.  I am not an engine builder.  I can assemble and install a head,
adjust the valves, change the oil, adjust the timing with the distributor
and install a clutch, but my expertise kind of ends there.  I certainly
appreciate all the input of the list though.  Knowledge of these engines is
not something I can go to the local mechanic about.
Mike MacLean

On Wed, May 24, 2023 at 6:47 AM Michael Salter <michaelsalter at gmail.com>
wrote:

> Speaking as someone who has over the years had 2 bouts of tappet failure
> in 100 engines I would suggest that you are wise to be cautious.
> I can't advise on the tappets that you have fitted but can say the I am
> now using sets from A H Spares which are proving to be very satisfactory
> and are different from those I have had problems with.
> I have, in B.#174, a magnetic oil drain plug and have found that to be a
> very good indicator of impending tappet failure. On the last 2 oil changes
> there was absolutely no metal on the plug.
> My procedure initial start procedure was to firstly remove the inner valve
> springs as I have found that they and the additional pressure that they
> produce are just not required as my engine exhibits absolutely no sign of
> valve bounce right up to the red line.
> I use Lucas 20/50 break in oil for the 1st 500 miles.
> On first start I held the engine around 1500 RPM for about 20 minutes. (I
> have difficulty believing that this is necessary but that's what the
> experts recommend so you have to be sure that the cooling system is in good
> shape).
> I change to VR1 non synthetic 20/50 after 500 odd miles and then change
> the oil every 3000 miles.
> The engine in B#174 now runs with absolutely NO tappet clatter which is
> pretty unusual for a 100.
> I recently checked the valve clearances and they were unchanged after 2500
> miles, another good indicator that the cam and tappets are holding up well.
> I'm sure others have had different experiences but I  would recommend that
> you make every effort to avoid a cam/tappet failure because rectification
> requires a complete engine strip down.
> Good luck.
>
> M
>  (Still running perfectly with outer springs only)
>
> On Wed., May 24, 2023, 8:46 a.m. Michael MacLean, <
> springer.mike51 at gmail.com> wrote:
>
>> 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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