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The mkiv Supra Owners Club

Cam clearence way offf


Rinus

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He there,

just pre-fitted hks 264 cams, torqued as the manual says..

Intake cam clearence between 0,04-0,06mm , exhaust between 0,10-0,12mm.

Should be intake 0,20 +/- 0,03 , exhaust 0,30 +/- 0,03,

Is this normal that all shims need replacement?

Had stock jspec noks in before...

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Can someone explain what is meant by Cam tolerances/clearance etc?

 

Where do I start, ok !!

There is a bucket that sits on top of the valve spring with a shim (spacer) in it. Once the cam is fitted and torqued, the cams have teardrop shaped lobes on then which give the lift. On each bucket and shim you need to rotate the cam so that the bottom part of the teardrop is above the shim. Then with the relevant feeler gauge check the gap between the shim and cam. To get the correct tollerence the shims are changed.

So in the case of the intake side the gap needs to be between 0.15-0.25mm.

 

Hope this explains Will.

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Ok, I knew I should re-shim,

but sometimes I see people who only had to re-shim 4-10 shims,

not all 24, so I thought this was a bid strange...

 

You won't have to re-shim them all. You swap them around for them to suit. By the time I swapped mine all around I needed 7. I could have ground them down but decided to just get new.

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0.2 intake and 0.3 exhaust are pretty standard clearances. I'd be surprised if anything massively different was quoted.

 

In case anyone is wndering why they are different, its because on he exhaust side at running temperature the valve elongates more than the head expands, and so the clearance closes up to about 0.25mm whereas on the intake side the head expands more than the valve grows, so the clearance opens up to about 0.25mm

Edited by Digsy (see edit history)
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Ok, I knew I should re-shim,

but sometimes I see people who only had to re-shim 4-10 shims,

not all 24, so I thought this was a bid strange...

 

Hi Rinus, it's a bit odd for HKS cams to be so far out. Did you check all the clearances on the original cams before removing them? If they were near correct I am surprised that all 24 are so far out. I use and recommend HKS and Tomei cams as they are usually machined to very tight tolerances mastered off the base circel of the stock cams. I would have to ask, are you sure they are genuine HKS cams form an HKS approved re seller? I have never seen counterfeit HKS cams, but China can copy anything these days ;)

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If it was less I'd have been concerned. More cold clearance might be a bit noisy - especially if the cam profile doesn't have ramps high enough to take up the extra clearance properly.

 

I checked it earlier and it's not 0.002" more than stock, it's actually just the upper limit of stock. 0.010" and 0.012" is the recommended clearance, it's 0.002" more than the stock standard rather than the max stock.

 

Make smore sense I guess :)

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@Chris, It sure looks like hks cams :search:

Its says hks in the cast and t083 has been drilled in intake cam and t084 in the exhaust cam,

wich says 264cams when I checked hks website...

Bought them second hand, they look very fresh...

I have to say I use wider feelerblades now, so they are as wide as the cam itself.

First I used a bit smaller and then 0,06 was like 0,10...

I have taken new feelerblades cause the small ones where like; 0,05-0,10-0,15-0,20

and the little bit wider ones where like; 0,02-0,03-0,04-0,06-0,08-0,10-0,12

 

---- =cam

-- =first feelerblade

 

---- =cam

---- =second feelerblade set

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