Tomei Poncams Type B Engine Knock

[kyle_24]

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.

[JustinP]

Did you check the clearances and set to 0.45mm?

Also what brand cam gears have you got and what model car are they designed to fit?

[Moodles2]

Tomei Intake cam gear won't fit because of VCT, unless you deleted VCT.

[kyle_24]

how do i check clearences? it has hydraulic lifters

[r32-25t]

If its an r34 neo engine, it has solid lifters

[KiwiRS4T]

Long shot - I had a knock at idle turned out to be the aircond pump - try turning yours on and off to see if it makes a difference.

[34GeeTeeTee]

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

[75coupe]

Is the cam belt over fitted?

If not are you using the the spacer behind the cas?

[wolverine]

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.

[kyle_24]

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

[r32-25t]

Just start with a set of feeler gauges

[abr33]

Yeah, feelers and verniers are adequate to do clearances...

[Hanaldo]

On the topic of clearances, I take it one should use the Tomei clearances and not Nissan's?

Edited July 17, 2012 by Hanaldo

[Simon-S14]

no you use nissan clearances regardless of the camshaft

[Hanaldo]

Even if using aftermarket valve springs and retainers?

[abr33]

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.

[kyle_24]

under the hood it says 0.20 and tomei says 0.45 i figured with the extra lift it would need the bigger clearance?

[abr33]

Lift doesnt really determine clearance. Nissan designed the valves and seats, do what they suggest

[GTSBoy]

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 July 17, 2012 by GTSBoy

[Moodles2]

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.