Purchased a set for exhaust side of my 66 fhc, but while researching for installation tips I ran across a series of old posts from 2008 in which Messrs Brady, Camp, et.al. said that failures in cars of this vintage are highly unusual. I inspected mine and there's no evidence of lifting. Obviously don't want to do this if it's not necessary as a lot could go wrong along the way. Any words of advice would be greatly appreciated.

Submitted by mr.jwhey@rocke… on Fri, 05/04/2012 - 12:11

ps Bill;

Got a chuckle from your comment they will just end up in the sump. You aren't by any chance a former hairy-chested Aston owner? "That's not a clutch......"

Submitted by bonnettoboot@e… on Fri, 05/04/2012 - 11:22

Self tapping screws! Why were you going to use them? I have always used helecoil inserts. If you do drill all the way through while using a vacuum you can still catch the swarf. & even if some gets away it will simply end up in the sump.

Submitted by mr.jwhey@rocke… on Fri, 05/04/2012 - 08:42

Based on both of your input I've decided to go ahead. My main concern is drilling though into the valve chamber. There doesn't appear to be much margin for error- especially on 3 and 4. Think I'll ditch the self-tapping screws in favor of tapped holes and loctite.

Thanks for the advice.

Submitted by bonnettoboot@e… on Thu, 05/03/2012 - 20:11

Hello Joseph, what i said still stands. The problem started when Browns Lane changed the installation procedure from heating the heads and freezing the guides, then, pressing them in with a 2 thou interference, to just pressing in. That being said, age is also a factor as aluminium degrades with time, so for the past few years we have automatically installed the exhaust hold downs. The only real issue is the shavings getting into the engine, we blank off the oil return channels, use a vacuum when drilling and tapping & do not drill the holes all the way through the head. Regards

Submitted by rcmaury@bellso… on Thu, 05/03/2012 - 16:40

Although not common, I have seen inlet side tappets on XK20 cars lift. That is why we lock all 12 down on a rebuild. Yours might not ever lift and most likely if not overheated, you will probably be fine. However, if it were my car, they would be locked down on both sides and in fact they are on my cars. The preventative is not expensive but the repair can be if they come loose. If you have already purchased them, then I would recommend installing them.