So in disassembling my friend's 2001 with a v6 after timing belt snap I found something really odd with the intake valves. I thought it was a sign of valve damage until I pulled the rocker arm and looked at the cam and now I'm just confused. This is on the front head specifically, we haven't done much with the rear yet. When you turn the cam the intake valves toward the cam sprocket barely move. The far rocker arm moves and moves the valve as I would expect, the center arm which from my understanding of VTEC on the 4 cylinders should be the VTEC controlling arm moves in a slightly different depth and timing, but the one closest to the sprocket barely moves. So I thought ok he bunged up those 3 valves in particular, let's pull the head and examine things. (We ran out of time that night and have not finished pulling the head yet so I cannot confirm from observation underneath) First I decided to pull the rocker arm. Well, the cam lobes under those 3 rocker arms are significantly shorter and timed different than the one on the other side! What?? Well that would explain why the leak down test on all three showed 60% loss and we could hear it out the intake. But I don't understand why it's so different. It doesn't look damaged or worn and at least for the 2 weeks he had the car before the belt snapped it ran just fine. Also, the service manual supplement I found for the v6 gives a different specification for that cam lobe as well (about 34mm for the primary - the one furthest from the sprocket - 36mm for mid and 31mm for secondary). Does anyone have the technical expertise to explain why and how this works and what this is for?? I'm having a real difficult time finding information about the unique things about this j30 engine! Thanks!

 

That is the normal function of the Fuel Economy designed VTEC in the J series Engines. When the engine is out of VTEC only 1 of the intake vlaves opens completely. The second intake valves only slightly lift off the seat, this is to ensure that fuel does not puddle up behind those valves when out of VTEC.

 

Ok, that makes sense. Duh. The valve is open when it's pushed down, not when the spring is holding it up. I knew that but somehow in my head it didn't click and I was thinking of it backwards. Thanks!!