Talk off topic about anything vaguely connected with Triumphs.

General Triumph Lounge Bar messages

I understand the reasons for fitting alloy valve spring retainers, and the advantages.

I also know that in the past, I have heard reports of failures of those sold by Moss, dropping valves into the engine with obviously disastorous results.

Looking at what is available on the market these days, from all kinds of sources.

I see many vendors merely referring to them as 'Alloy', which tells us very little, whereas one calls them 'Aircraft Alloy' - still a very broad cover-all term.

One calls them 'T6061', and yet another calls them '7075'.

These are both 'aircraft alloys' and the 7075 has a much greater tensile strength than the T6061.

Does anyone have any actual experiences, both good and bad of using different suppliers alloy valve caps?

If you do, then please tell me!

I am afraid that I have little faith in companies that do not give proper technical descriptions of their products, especially critical ones, such as valve retaining caps and/or cam followers.

Thanks in advance for any help provided.

Best Regards

L&195;&169;on

Leon

I've had Moss alloy valve caps on my race engine for the last 9 years with no problems, even after changing heads, valves and springs at various times over that period.

Engine has a race cam (264), stiffer valve springs, standard rocker gear and is regularly at 8000 rpm. Though is not high mileage.

Cheers
Andy

The engine that came with my Vitesse when I bought it was built up using some alloy valve caps. Almost every one had signs of wear when I stripped it. Dave Pearson thinks these were from an unhardened batch that got out into the market - he has some just like it in stores. He identified them as unhardened many years ago and put them to one side intending to get them treated, they aren't for sale/use as is. These may have been inherited stock from the old Kipping days as he can't recall acquiring them and they have no identifying marks. They are not the kind of thing you want in your engine really!

leon i too ran ally valve caps for around the last 15yrs from triumphtune at the time i think.i did notice ridges were forming where the spring contacted them due to continual contact and vibration i thought but on further inspection it was from the top coil of the valve spring where it had been ground off leaving a sharp edge.i removed this with my die grinder and linished them to a smooth finish which stopped that problem.they did not seem overly hard as in heat treated and was relativly easy to scribe a number into them purely for reference when stripping the head, i would say longevity is the issue with these as with continual cycling of heat from the engine they could prematurely fatigue due to accelerated annealing causing them to go brittle.IMOH if you want reliability in the long run it may be better to go for steel with a perhaps a slightly harder valve spring to avoid valve float,but then again there's many other variables of the valve train to be taken into account here.....

ps. on my current head i'm now using chris witors version but the engines only been running for 2 weeks so it's a bit early yet for any opinions......

paul.

Thanks all,

Helpful advice, the more the better.

Best regards

L&195;&169;on

Hi Paul,

A very helpful email.

I have heard, and continue to hear, horror stories about TT alloy valve caps dropping valves into engines, but it seems to depend on a few variables, such as valve spring rate, RPMs used, and how the car itself is driven. i.e. the TT alloy valve caps do not seem to stand up well to increased spring pressures such as found with the TT springs, higher rpms also increase wear, and race use is definitely bad for them.

I do not have any information as to how the various alloy valve caps on offer may have been heat treated, or more properly tempered, but much of their strength comes from the grade of 'aircraft' alloy used such as T6061, or 7075...the tensile strength of the 7075 being much higher than that of the T6061.

for example:

6061-0 (untempered) has a tensile strength of 22,000 psi,
and a yield strength of 16,000 psi.

6061-T4 (tempered) has a tensile strength of 30,000 psi,
and a yield strength of 16,000 psi.

6061-T6 (tempered) has a tensile strength of 42,000 psi,
and a yield strength of 31,000 psi.

compare that with:

7075-0 (untempered) has a tensile strength of 40,000 psi.
and a yield strength of 21,000 psi.

7075-T6 (tempered) has a tensile strength of 74-78,000 psi.
and a yield strength of 63-69,000 psi

7075-T651 (tempered) has a tensile strength of 67-78,000 psi
and a yield strength of 54-67,000 psi

So it can be seen how critical the selection of the correct grade of alloy is for this application, indeed any application. ps. some aircraft wings are made of 6061 and some of 7075...I choose the 7075!

Unfortunately, almost all vendors do not think it neccessary to tell us what grade of alloy has been used

Apparently, valve bounce is less likely to be a problem using new original springs, with a camshaft with valve lift below 0.430", duration of ? and keeping revs below 6,000 RPM.

I am against valve springs of higher spring rates because of the significantly increased wear and tear on all the components of the upper valve train on our OHV engines, especially valves and cam followers/tappets/lifters.

This wear and tear has recently been exacerbated due to the significant reduction in Zinc & Phosphorous (ZDDP) Anti-Wear additives in engine oils.

Gasp!

All I want is to have faith in the parts I am using!
I cannot afford to make expensive errors.

Please stay in touch Paul, about your experiences with Chris Witor's parts, for that is what I have ordered. Let me know exactly which of his parts you have installed.

Best Regards

L&195;&169;on

leon,

i,ve just come back from the pub and whilst there i had a chat with a friend of mine who is a materials buyer for an engineering firm which make parts for british aerospace and several F1 teams amongst others and he suggests T6 alloy for it's durability.tensile strength tests as far as i know are a one off test on a given section of material so i would suppose durability is probably more important.........anyway it got me thinking and i remember an article i have in my engine tuning archive(applies to all engines not just triumph)which i have built up over the years and i have a piece by david vizard from the early nineties about using titanium for various engine parts;same weight as aluminium(or is that aluminum to you now

with the strength of steel,obviously the best of both worlds,but the only down side is it's prohibitivly expensive cost in raw material and manufacture process.worth a thought for the racers maybe as a fit and forget component in as much as not requiring replacemnet for a long time.maybe if enough owners are interested something could be arranged for a production run?....

paul.

Thanks Paul,

I initially liked the idea of Titanium, and discovered that Titanium Caps are already marketed here in the USA, by APT in California, (a company owned by a Brit)...they are naturally expensive.

And then I got this, from Gareth Thomas in Russia, no less:

If you use titanium spring caps you HAVE to use titanium collets, then of course you should be using titanium valves as well then of course....which are not really suited to OHV engines.
Why?
Titanium galls like the blazes with dis-similar metals, like when they fit steel bolts in Ti rods.....(just find someone happy to make Ti rods these days !!!)
+
just like it corrodes other ferrous metals to pieces in salt water, and heat treatment is quite a fun job too!

Strikes me as kinda crazy to make Ti stuff in the states when the metal comes from Europe...but it takes all sorts I guess......(but I suppose I have quite a bit to do with Ti in general on an everyday basis )

say na more...

OK, L&195;&169;on back again:

ps. I use Aluminium when I am talking about stuff on British cars, aluminum when talking about stuff on non-British cars...

I might have that Vizard reference book in my library, but my respect for Dave Vizard fell off a cliff recently when he started endorsing another 'snake oil' engine oil additive, in which he now has a vested interest!

shame.

Section : General

Alloy Valve Retaining Caps

Followups :

Alloy Valve Retaining Caps

Alloy Valve Retaining Caps

Alloy Valve Retaining Caps

Alloy Valve Retaining Caps

Alloy Valve Retaining Caps

Alloy Valve Retaining Caps

Alloy Valve Retaining Caps