[Healeys] Denis Welch Tappets Again

[m.g.sharp at sympatico.ca]

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

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/healeys/attachments/20230524/1f463371/attachment.htm>