A series strip down, Valve tip problem found

[rusty998]

Hi
i have a A series 1310 that i am in the process of stripping down, the engine came from a ex hill climb car, the first port of call was to remove the head strip it down for inspection, so head off, roller rockers off, springs and then the valves, this is where i have found the first issue, all but one valves came out, but one exhaust valve would not slide out of the guide, closer inspection found that the end of the valve was damaged/worn as was the roller tip on the rockers, i had to file the burs from the end of the valve to be able to remove it,
damaged valve on left,

worn rocker tip

worn valve guide

now having inspected the head etc would i be right in thinking that one i need to replace valve guides, and two valve/valves as needed ?
any advice of what may have caused this would be much appreciated .

[aseriesandy]

The guide looks a little worn oval? Maybe the valve is slightly bent and the rocker arm and roller has had to work harder to overcome the friction caused by it not being straight. Sure all will be ok if you replace the guide and valve. Check the rocker shaft and rocker for wear as well as it may also have suffered.
Good luck.

[skylinedave]

It could be a few things , with it being a second hand engine you will not know for sure . Maybe the valve was a little bent , maybe the guide was worn allowed the valve to oscillate against the rocker ?

They both need replacing anyway .

[rusty998]

thanks Andy
i was intending to have the exhaust guides replaced when i noticed they were of an oval shape and different to the inlet guides,
which guides do you think i should have fitted ? steel or bronze ?
Also what type of valves are available suited for fast road use?
i have read that race valves wear quickly when used in a road car due to the higher millage/use it has over a Race car which does far fewer miles?

[skylinedave]

Just replace it with a similar valve . I would speak to a engine shop about guides , i think a bronze or brass guide it a upgrade , i do not know if they last a long time for road use or are for race , something any half decent builder will tell you .

[steveg]

Could the valve springs be binding at all ? It would be strange for just one to do it unless someone has been running with too little valve clearance on just that one though..

[rusty998]

It's fitted with double valve springs,
They didn't bind up when I was turning the engine over by hand, and it was running albeit 14 years ago,
think they last guides I had fitted to a head were the bronze type but will talk with the engineers first on which would best suited for me,
Cheers

[aseriesandy]

Skylinedave is spot on. Just replace the damaged one like for like. There are so many variations in valves for the A series engine. If it is a factory valve it may have an AEG number on the stem. I have messed about with minis for years and when asked what is the best way to make them go faster my reply is always the same. "let my wife drive it"

[rusty998]

Fitted the valve back in the head and it was correctly seated, so will just replace the guides and valves and run it to see if they problem persists,
Cheers

[dontliftoff]

hi might be an idea to check the roller on the rocker arm looks to me like it may well have seized causing the arm to cam on the valve

[rusty998]

The tip/roller spins freely, I have been on a mini forum to ask them question on there, ACDodd replied and said that using high lift roller rockers increases the wear rate,
they don't put that information in the sales add, Hmmmm!
So I will either get the guides replaced at a later date or sell the head, I have another Cooper S head in the shed that has had the work done and can put that together with the rockers and double valve springs from the head above,
Thanks to all that commented with help much appreciated
Rusty

[skylinedave]

I would just whack some standard rockers on there if you have some or some repro/gen cooper s ones 1.3 ratio . It seems roller rockers are a bit overrated .

Ac Dodd knows his stuff and is a good chap !

[rusty998]

Do you mean the 1.3 type sold by mini spares?
The 1.5 does seem to cause problems that they negate to tell you when you buy them!

Yes I would agree with you on ACDodd, very helpful chap,

[skylinedave]

Yes the 1.3 rocker , cooper S , about £7.50 each , fit to your existing rocker shaft . They are not ' roller rockers ' or made of anodised aluminium , just standard parts with a bit extra lift . A lot of people think they are a waste of money , especially if you have a uprated cam .

I would ask on the mini forum some more to get some extra views , as you may just be better of with a standard set .

Hope this view helps .

[v8ian]

A badly set tappet will cause premature wear like that if its not corrected, another thing could be the valve tips have been cut down to suit your geometry, its always possible the hardening had be compromised.
As for altering Rocker Ratios, you can help the exhaust flow on an A series as its 3 port by using 1.5s on the Exhaust and 1.3s on the inlet, Mixed ratio rockers don't usually cause any problems,