Hi!
Does anybody know what are valves lifts at top dead center on stock h22a camshafts in vtec?

thanks!

 

lift @ TDC is 0

 

if it so what overlap is?
i thought it is angle range at which both intake and exhaust valves are opened near TDC

 

well the valves are opening and closing "near" tdc but they are nowhere near peak lift.

if the valves were open @ tdc not only would they hit the piston but there would be no compression.

peak valve lift occurs "roughly" around 100 degrees before and after tdc depending on the cam

i have never measured peak lift or found where it occurs on a stock cam.

 

He is asking about lift at TDC in overlap. Or in the non firing cylinder. I do not know the stock cam number in VTEC but a Pro3 has the IN open .195 and EX is .182 @.000 lash. Lash @ the valve is .009-.010 IN. and .012-.013 EX.

 

yes. I meant tdc at the end of exhaust stroke and at the beginning of intake one.

 

ahh

btw lash is .007 in/ .008 ex

 

No, it is not on a B or H series. That is the cam to rocker clearance, to get valve clearance you need to multiply by the rocker ratio, which is 1.55. You would be correct on a D series.

 

Thanks, but valve clearane i can get from ESM
I meant not clearance but valve lift.

In any case I already have ordered new pistons, hope with h23 crank they will not meet valves in TDC.

 

you said "lash"

you gave him opening and closing lifts @ 0 lash and then went on to say valve lash is 9-10 and 12-13

when 99% of us here refer to "lash" we are talking about valve lash (clearance between cam and rocker).

and who measures valve clearance by multiplying the rocker ratio? assuming you mean p2v or v2v clearance?

 

also TDC is when the piston is @ top dead center (obviously) for the cylinder in question. if you are asking about a non firing cylinder then it wouldnt be TDC, it would be referred to as BTDC and ATDC (before and after top dead center) at any given crank angle.

why are you worried about valve clearance when the piston is down in the cylinder anyway?

check your clearances while the piston is within 20 degrees either way of TDC in the firing cylinder.

you guys are confusing

 

While on the subject of confusing, maybe he is more correct in calling his way valve lash. Although the first part of your statement here is true, it sounds funny because valve lash doesn't actually reference the valve itself, but the cam side of the rocker. Your way (the normal way) sounds more like rocker lash. Then again if we started calling it rocker lash people will probably ask you to clarify lol

Like mentioned, contact wont occur at TDC necessarily, even though this is when the piston is at its highest, due to the aggressive ramp angles of the cams. it will depend on the specific timing but common valve contact occurs if the piston catches up to the exhaust valve as its closing if I recall correct...can't remember where I heard that though. Maybe the intake valve catches up with the piston as it is accelerating away from TDC.

 

true his use of the word valve lash to refer to p2v clearance could be considered correct although its very uncommon for the most of us

however when you read any english written service manual or cam manufacturer specs/instructions they all use the term valve lash to refer to cam to rocker clearance (valve adjustment spec)

not a big deal, just a bit confusing

 

Like already mentioned, the least amount of clearance is BTDC for the exhaust and ATDC for the intake. The only time list is zero at TDC is between the compression and power strokes of the engine.