Found out today what was going on with no. 6 cylinder. Plug was wet with oil. Drove it really hard over the weekend.

I pulled the valve springs and the valve seals. Lo and behold the intake guide snapped off at the base of the head.

Never saw that before.

i would love to see a pic

That is a new one. Any signs of retainer to seal contact? 

Where the valve seal snaps on? Could your cam lobe push it down?

Edited July 25, 20178 yr by siteunseen

I will get a picture of it. This is a E31 head with bigger valves and had been raced hard in the past. I sold the race cam and the super nuts stiff Isky springs.

I put a smaller Schneider cam and softer Schneider springs in it. I think this was fractured at the time and I never noticed it. I even put the valve seals on it.

The plug was a bit wet with oil lately, then when I was on the track Friday it got soaked with oil so bad I was running on 5 cylinders. It finally fully broke I expect.

I dropped off my original N42 head that was on the engine at the machine shop this morning. He is going to tank it, do a surface cut

and install all new Nissan valves that I already had. I will just swap my cam kit to this when I get it back. I want to get some more driving

in this year while its still warm weather up here. Got a photo coming next.

Here are the pieces I found. I have no idea what the small ring is, but was under the valve seal. First one shows where it separated at the head.

 

 

that valve stem looks like it has a shiny spot on it. it it was bent it would cause that damage since where it broke is the weakest point