Thread: Supertech over sized valves and cam timing

I'm getting my car dyno tuned next week and right now my b14 has:

Supertech +1mm intake/+2mm exhaust valves
sr16 n1 cams at 0/0 timing
BC dual springs and retainers
CS cam gears
1mm shaved head
port and polished head
Calum RT ECU

Is there a max I can have the cam timing at? Any other precautions I need to take when tuning with the oversized valves???

I guess you or your engine builder did not take the time to check your piston to valve clearance. Are the pistons fly cut for the larger valves? If not then you probably have little or no room for adjustment.
In the words or Roger Clark you risk piston to valve interface.

If you do not know who he was here is a small example.
YouTube - Tour of Britain 1974

the bottom end is stock
How much room if any at all will I have??

.. i woudlnt risk it.

But is the engine running normally? I also think you need the notches

The engine is running good, I can hear some ticking in the engine though. I have probably put 2k miles on the motor, never got it above 6k rpms.
Guess its time to build the botton end.

the ticking should be the shims, needing adjustment

so your supertech valves are 1mm or 2 mm bigger or longer? (normally oversized valves are bigger diameter). if the other critical specs are the same as oem sr20ve valves,and the head/block wasn't shaved or resurfaced i see no reason why the same limitations shouldn't apply. adjust to where you want them (within reason) and test by manually locking in the big lobes and turning the motor by hand.
fyi, i'm running n1's @ +5 in/-6ex to 8k . i think this is getting pretty damn close to the limit, however

I forgot to add to the top the head is shaved 1mm. The valves are bigger and not longer.

with a 1mm shaved head I think you can go +4/-4. I would try +4/-4 and install the cams and check valve to piston clearance.

If you have oversized valves and you did not notch the pistons for wider valves, then I would not press it.