When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
Do the TrickFlow address the inherent geometry issue of the OE head?
What geometry issue are you referring to? I'm aware of the guide to seat concentricity issues in OE heads...but a quality rebuild of stock castings from places like AHP, AI, WCCH fix that issue.
Early on there were reports that some OEM heads suffered from incorrect machined rocker pedestals that located the rockers incorrectly in relation to the valve tips, causing undue scrubbing and premature guide wear.
Early on there were reports that some OEM heads suffered from incorrect machined rocker pedestals that located the rockers incorrectly in relation to the valve tips, causing undue scrubbing and premature guide wear.
Several of the nay-sayers and gents that personally attacked people that disagreed with them drove away the guy that discovered it with hateful accusations. These less than desirable individuals for the most part have moved on. The guy that discovered the problem actually designed and made a go-no-go gauge that would show if your pedestals were off. He even freely shipped the gauge around to all individuals that wanted to check theirs. His board name escapes me now at the moment. This was one of the reasons that I went with aftermarket heads 4 years ago.
Several of the nay-sayers and gents that personally attacked people that disagreed with them drove away the guy that discovered it with hateful accusations. These less than desirable individuals for the most part have moved on. The guy that discovered the problem actually designed and made a go-no-go gauge that would show if your pedestals were off. He even freely shipped the gauge around to all individuals that wanted to check theirs. His board name escapes me now at the moment. This was one of the reasons that I went with aftermarket heads 4 years ago.
John G...sharp guy. He's in a C7Z now. Wasn't sure if that actually did prove beyond a doubt on the rocker pedestals. Certainly haven't heard AHP (or others) mention any heads having a bad wipe pattern due to pedestal machining, and that's one of the things they check on their head rebuilds.
Hi there. I live in the peanut gallery. Sometimes I see really stupid **** posted on this forum that inspires me to provide an opposing point of view for comment. Not so much lately, as I don't have time for this silliness....
The LS7 is not a 7000 rpm engine. Factory fuel cut off is 7200 rpm. That is the first stupid statement to clear up. If you don't think 200 rpm matters, well then I suggest you pick up a couple books and start studying basic ICE theory. Start with Heywood. Here's my favorite. https://www.amazon.com/dp/007028637X...=IOKNY95UBF9CC
Now, let's just imagine a situation where you're rallying about and tap the rev limiter in second and go for three.... Miss the gate and land in N. Don't realize it due to the adrenaline rush, and hammer the go peddle in Neutral. Do you really think the fuel cut off will stop the revs at 7200?? Try it. Mine didn't - twice. Reved to 7600 both times. Fluke or PFM, I don't know. Don't really care cause I saw it. So I don't focus on this "7000 max rpm" that those who don't reside in my peanut gallery focus on. I focus on 7600 rpm. Maybe I'm too conservative, or just plain stupid. Whatever, I'm too damn old to change now. And my engines are known to live long healthy lives, so I'm not about to change my conservative methods or approach to engine building.
So to those who don't give a **** about valve weight, rev that f'er up to 7600 with your petit solid stemmed intake valves and let us all know how that works out for you. Until then, I'll just stick to what I know in my little corner of the world, which I call my "peanut gallery".
Oh, proof of stock calibration rev limiter settings. (I don't just "talk" about building race engines and tuning my own ****, I actually do it).
Actual real world tester here with factory rev limiter in a boosted application.
It's not uncommon for engineers to disagree. I haven't seen a failure with TFS 260 heads that indicate a heavy valve was the source of the issue.
There are lots of reasons why your theory could be right or wrong. Lighter is almost always better. It doesn't mean that the heavier valve won't work just fine for most stock-ish LS7s handling street or weekend warrior duty. Katech's Spintron testing was very useful if you're using the tested components in an OEM head. It seems like people like to apply those findings to everything related to the LS valvetrain. Maybe it's the best data we have, but it's incomplete if you're talking about a different casting, using a different guide, different valves, different springs, different retainer, different locks, different seat, etc. If you want to error on the side of caution, get you some fancy molybdenium and MoldStar90.
Whatever you and I say here matters very little. Sometimes the math says one thing, but the actual experience is different. It's practically impossible to disprove your theory. I suspect the peanut gallery will never be satisfied unless LS7s start coming apart because of TFS intake valves or TFS discontinues solid stainless valves and increases the price. Until then, many of us will be enjoying our out-of-the-box TFS 260 heads.
11-17-2016, 04:55 PM
