[Healeys] Valve gap theory : BN2

[Austin Healey]

Just one addition: normaly the profile of the cam and the valve gap with
"normal" use is a connected issue. The camshaft profile has a section called
"pickup phase" which is to make the rocker hit the valve tip "smoothly". Soo
for longevity it is the best to use factory specs if the car is used
normaly. For track days You may want some extra clearance, and for
meetings/going to the local theatre/taking the lucky gilf for a drive :)
maybe it is better to set the valve gap a bit tighter.

A clear sign if You set the gap too tight is that after some minutes of road
speed, You get rough idle (or no idle at all!) with some cylinders out.
After cooling a bit down, things go back to norm.

Gergo

2011/6/19 Austin Healey <pajtamuvek at gmail.com>

> You can damage Your valve seats and valves. - if the gap is too tight
>
>
> 2011/6/19 Austin Healey <pajtamuvek at gmail.com>
>
>> If You use the car mild and never race it, You can close the gap a bit. I
>> dont have experience with Healeys, but on the Mini, factory clearance is
>> 0.35mms, and on my road cars I used 0.25 without any long term effect.
>> Bt if You push the car (more power-more heat), You can damage Your valve
>> seats and valves.
>> I dont think that there is any measureable power gain from tighter valve
>> clearance.
>> Too big gap can damage valve tips/rockers.
>>
>>
>> 2011/6/19 Greg Lemon <glemon at neb.rr.com>
>>
>>> You get a little more valve lift (like having a slightly hotter cam) if
>>> you tighten the gap.  However, as things heat up and the metal expands you
>>> may not get the valve to close all the way, and hot gas will get by and burn
>>> the valve.  I have never read anything suggesting you should tighten the
>>> clearances up for a little more performance, the very limited benefit is no
>>> doubt not worth the very real risk of the burned valve.
>>>
>>> Greg Lemon
>>>
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