-TheBandit-

iTrader: (1)

Does anyone know of a good writeup or step-by-step for checking p-v clearance on a VVT engine? I'd like to do this without pulling the heads if possible.

Here was what I was thinking to do with an assembled setup and checker valve springs:
- rotate the crank in X deg increments
- for each increment:
-move cam to full advance (can this be done with a socket on the phasor bolt?)
-press down on each valve stem until the valve contacts the piston
-measure distance with dial indicator
-move the cam to full retard
-repeat measurement
- repeate for a range from about 20*BTDC to 20*ATDC until minimum clearances are located for int and exh. (according to this article, minimum clearance is typically found at 10*BTDC for exh and 10*ATDC for int)

Is a solid lifter necessary for this when using checker springs?

Would it be valuable to take measurements between full advance and retard of the cam?

cam

iTrader: (9)

Are you using the phaser limiter kit from Comp?

My thinking was to simply rotate a few times at full advance ( which is where the start position is ) and then retard it full with the help of someone on the bolt and spin again slow of course. If nothing hits fire it up an go

-TheBandit-

iTrader: (1)

I plan on using a phase limiter, but I'm not sure if I'm going with Comp, Mast, or some other manufacturer - it will probably be one of the two and I will use their matching phase limiter, pushrods and valve springs.

-TheBandit-

iTrader: (1)

Anyone else have input?

SteveB4C

If you check it at full retard that is when the valve is fully open closest to TDC, right? So if you check it there it sould be ok at full advanced cuz the valve will be opening and closing earlier in the power/exhaust stroke. I could be wrong but thats my theory and it could save a bit of time.

Jimbo1367

wow. where did that come from?

-TheBandit-

iTrader: (1)

I would think the primary concern with cam timing would be with advacing the intake valve opening since it starts opening before TDC. Next concern would be retarding the exhaust closing since it happens after TDC. When advancing, the intake valve would start opening earlier and therefore could be more open when the piston is at TDC. Exhaust normally closes ATDC, but I suppose it could be on the closing ramp near TDC and therefore if the cam is retarded and it's closing later, that could cause some problems for the exhaust valve.

Exhaust opening and intake closing both happen nearer to BDC so I don't think they're a concern.

Basically I think both the advanced and retarded extremes should be checked. What I'm not sure about is the in between.

cam

iTrader: (9)

You shouldnt be. It wont hit midway through the cam movement and not at full retard. Meaning if it clears at max retard then it will clear at zero and everywhere in between. If you use the comp phase limiter it locks out all cam advance and allows 20 degrees of cam retard and thats it. so if you spin it where it "wants to sit" at zero and its all good then retard the cam to its maximum and spin it and if it clears your good to go.