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The mkiv Supra Owners Club

Its all in the head...


suprafan72

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Hi All,

 

My head's come off today and Gold Tappet Shims Interesting...

 

Here are some Pics.... I know why now the japanese build there engine's well... Allso i've found out im running 272 intake and exhaust cams and very big valve springs with lots of porting thats been going on...

 

I guess the gold tappet shims are to support what the 272 cams can do to standard shim surfaces when they come in on song?

head1.jpg

head2.jpg

head3.jpg

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might arnt goldy looking, just plain silver :D
That's odd. Mine are definitely a gold colour.

 

The head is far from Stock... Ill take some closer pics when i get chance....The gold coating is for hardening purposes....
I was talking about the shims not the whole head.
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Is the gold colouring 'Titanium Nitride Coating' ? Used alot in engineering for wear/hard surface.

 

Paul

 

Well done Paul and yes it is!!!! Hence the shim heads have been coated in this due to the cam characteristics on the car... and the way its been set-up...

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Jakes offline so I'll part answer - he has uprated cams.

 

Unless he's refering to one of the other cars he has/had, not sure what were in those.

 

I guess thats why his shims may have been nitrated... I believe if high lift cams come on fierce it tends to soften the stock coating on stock shims (i.e breaks it down) The audible effects i believe is the famous ticking noise coming from the head....

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I guess thats why his shims may have been nitrated... I believe if high lift cams come on fierce it tends to soften the stock coating on stock shims (i.e breaks it down) The audible effects i believe is the famous ticking noise coming from the head....

 

Its to do with the amount of wear caused by a fast accelerating ramp.

 

Force = mass x acceleration.

 

Mass is fixed, so force depends on the amount of acceleration. A 'soft' cam has mot so much lift, so doesn't need to have such a steep ramp (in basic terms :)).

A high lift 'race' cam may have a lot more lift, so needs to accelerate the tappet a lot faster to get it opened & closed in the same time as the std 'soft' cam.

So the forces are much greater, which is why race cams wear themselves and the tappets much faster.... and its not helped by overly stiff valve springs either!

 

Quite a balancing act to get it all working properly :D

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