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Tomei Poncams Type B Engine Knock


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Skyline r34 gtt (rb25det neo)

I just installed some tomei poncams type b 260 degrees 9.15mm lift and as stated by tomei no need to upgrade the valve springs.

i also installed the adj cam gears but only the exhaust side would fit, intake cam gear didnt match the intake camshaft. so i just used one old and one new

the timing is perfect and the knock is only on idle and coming from the exhaust side.

at first i thought it was the CAS but not too sure.

im running stock afm and injectors at the moment but will upgrade once the knock has gone and it hasnt been tuned yet but that shouldnt cause a knock.

any help or suggestions would be much appreciated.

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If its an r34 neo engine, it has solid lifters

This!!

They should be a drop in application, if you have done that and have the Ex gear set right it should be fine... Mine are sweet :)

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This!!

They should be a drop in application, if you have done that and have the Ex gear set right it should be fine... Mine are sweet :)

Just for future reference, whilst they may "drop in", valve clearances should be checked and re-shimmed as required.

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the clearances recommended by tomei are diff to the clearences noted under the bonnet. i did not even bother to check them as i thought they were hyd lifters. guess im gonna need a micrometer

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Yep, nissans clearances will be a better guide. and 'close enough' isn't good enough either keep in mind too much it'll slap the valve up and slam it on seat, too little and the valve wont get enough time on the seat to cool.

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Actually the initial/final ramp rate has a lot to do with choosing clearances.

Having said that, going from Nissan's 0.2 - 0.25 sort of clearance to the 0.45 territory suggested by Tomei sounds like madness. You might add 0.05, not more than double.

Edited by GTSBoy
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Don't trust those stickers, as part of compliance there has to be a sticker mentioning timing, clearances etc. Well mine says BTC of 15degrees (RB25), which if you know RB26's actually run a BTC of 20 degrees.

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