74u

iTrader: (9)

Did a leak down test on my 416.

Procedure - Tested all 8 at TDC while cold 55F ambient, and the three easiest to access after 4-5 minute idle warm up time.

I found the leak results hardly changed hot vs cold.

#1 - 14% cold (leak past rings)
#3 - 16% cold - 16% hot (leak past rings)
#5 - 17% cold - 19% hot (leak past rings...maybe a bit leaking past exhaust valve...barely audible)
#7 - 15% cold - 16% hot (leak past rings)

#2 - 25% cold (leak past intake valve and rings)
#4 - 16% cold (leak past rings)
#6 - 14% cold (leak past rings)
#8 - 13% cold (leak past rings)

The percentages were a bit higher than I hoped for, but considering the rings were gapped for moderate nitrous and it's not blowing oil I'm not too concerned about the ring seal.

I am concerned about the leaky intake valve on #2...tapping the rocker with a dead blow hard enough to unseat the valve and loosening the rocker didn't change the leak at all. Loud & clear leak.

The reason I performed the test is because the combo has never produced the power I had expected (made 475/454 --- was hping for 500/480 minimum) with the combo listed below. In your experience how much impact would the leaking intake valve affect power? Will it hurt anything to run it as is, or should I pull the heads and have it fixed?

LS3 Block - 4.070" - .045" quench - 11.2scr
TEA CNC'd TFS 225
Tick Custom Grind - 239/246 - 624/595 - 113+2
FAST 92 / 95mm T-body - 100mm MAF
1 7/8 & dual 3"

Youngblood16

It could mean you have a chipped valve seat or a cracked valve, either of which could further break up and cause harm to your motor. You could also have a bent valve which is also not ideal. I would pull the head if it was mine.

Also how long has this setup been together? And how big are your nitrous shots?

74u

iTrader: (9)

It's been together for about 7-8 months and about 10k street miles.

So far it's only been hit with a 75 shot a hand full of times..less than half of a bottle used.. I left some room to grow with the ring gaps...maybe a 200-250 one day.

Youngblood16

what kinda valves/seats do you have? And how long does the car sit usually

74u

iTrader: (9)

The heads were purchased new from Tick (TEA built) last March. I'm sure they are stainless valves...not sure about the seats.

It's my daily driver...no sitting since built.

Youngblood16

My guess was going to be a rusty valve seat and the valve wasnt seating properly... Dam man a daily driven 416, you must love paying for gas. Maybe you have a slightly bent valve? If theyre that new and its driven everyday(or close to it) there's no way it sat long enough for any problems to occur(unless a part has failed or is beginning to fail). It sounds more like you've had a problem the whole time... what kind of rockers do you have?

74u

iTrader: (9)

Stock rockers w/trunion upgrade...PM guides.

Actually mileage has be acceptable in my opinion...14-16mpg in DFW traffic jam commuting. 22-24 on highway trips. But I was use to driving a Suburban to work so I guess my calibration could be off

There was a TON of P2V clearance when I built it...can't imagine a bent valve (from contact anyways).

A.R. Shale Targa

iTrader: (2)

Your valve could be bent from the pushrods being too thin (wall) or the valve springs not being right...although I'd doubt that if TEA set them up.
You are right in your expectation for that combo which seems quite badass.
I would absolutely pull the head !! No questions !! You've diagnosed the issue and it certainly won't fix itself or go away. It can and will only get worse or cause much worse carnage if the valve head decides to part ways with the stem....EEEKS

Youngblood16

I was thinking you may have a worn valve guide and maybe the valve isn't seating straight or it bent it. I mean the heads are fresh and theyre aftermarket castings, it seems unlikely to me they were setup improperly by TEA. Obviously parts fail all the time though, and you cant rule out having a defect.