REDSEE5

Hey guys! I’m sure this has been posted before but: I just got my Z two weeks ago and I’m going to pull the heads on Saturday at a buddies shop. I found a place close to me that does all the designs for Trick Flow (Total engine Airflow) and they quoted me $1,300 for the fix.

I have a buddy that is high up at Summit who said he could get me trick flow heads for $1100 a piece and the only other additional things I’ll have to buy is the trunion kit and gaskets. He claims I won’t need a dyno tune. Can anyone confirm this? He said the specs are all the same as the stock LS7 heads.


Also, if I do aftermarket heads will that pretty much eliminate the worry of a valve drop? I would just hate to spend $1500 total to have to recheck the heads every 10k miles.

Thanks in advance and sorry for beating a dead horse!

Unreal

TF heads will come with crap valves and all sorts of other issues. Good castings but they need work and all the junk parts swapped out.

No aftermarket heads don't eliminate the worry of a valve drop or even worn guides. All depends on the valves, guides, setup, cam, etc etc.

OneMeanZ

I've gone back and forth on this issue and believe I've settled on going the Katech route. I thought for a bit that it was just a valve concentric issue, so had originally planned going AHP w/ MS90 guides and be "done". But the more I researched and a few threads that have popped up here have me believing its a combination of concentricity and intake valve coating. I really don't like the idea of reusing the stock intake valves and what Katech is saying makes a lot of sense. So they replace intake valves with their Ti/Mo valves and use bronze guides. A couple guys here have had their heads checked going this route and all still in spec after taking a fair amount of abuse. It's more expensive (~2500) for this, and about 400 more if exhaust valves need replaced but they've been in the game a long time. And to Unreal's point, I'll be staying with stock cam/manifolds and only upgrading lifters while I'm there. I feel good this will work well for what I'm wanting out of the car.

STANG KILLA SS

your gut reaction was correct. go AHP MS90 and be done.

NemeZ

Another vote for this as well. If I could do it all over again I would go with ti/mo valves and bronze guides. As far porting AI has a killer program.

matt95

I'm in the same position, what's the best route to resolve the head issue? Sure wish I knew the answer.. Agree the Katech route seems like a great plan. I've read the stock valve wall thickness has changed over the years, no idea if that's true or not. If it is, good reason to NOT re-use them.

Indepth

You're just down the road from me, been down this road myself and have spent hours pouring over all the threads on here and gathering info elsewhere.

Unreal is correct. My heads were machined at TEA, but I kept my stock castings. What shop are you using locally?

If you'd like to talk more, shoot me a PM.

MikeOC

It seems to me as long as you replace all 16 valves, the intake for the coating, and the exhaust from the stem walls, and the new guides and seats are done competently, there should be no issues with the stock castings. Personally I wouldn’t go over the stock weights much which means aftermarket Ti on the intakes at a minimum. Take care of rockers if you fall in the applicable years, and maybe even a cam to avoid any potential soft cam issue and the top end should be “fixed”. But guides will still be a wear item, how fast depending on cam, guides, and use. You shouldn’t have to worry about checks every 10k at least.

REDSEE5

Thanks guys! I got a majority of it done today. I was feeling cocky and thought I could get the job done without removing the manifolds and just kinda bend them back to get to the head bolts, but I was wrong.

Everything else is done, but tomorrow im going to disconnect the manifolds from the cats to give myself more room.

Im having “Total Engine Airflow” do the heads and supposedly it’s going to take 3 weeks. (They are local, but said they have to send the valves to the original valve company to get them recoated.....Sounds like a temporary fix to me.)

Either way, this car is badass and I’m in love with it. But it has me paranoid to drive it how it’s supposed to be driven.

mykream

I spoke with Russ about this and gave him some options for you. Do not fall for the hype of AHP on here. I told Russ another option for you would be to get ahold of RPM and see if they have a set of heads done by AI on the shelf that you could send them yours and they will swap them out for an already done set. You will be good to go with TEA as well though. I told him that a good option for you valve wise would be to keep the stock titaniums, get them polished, and move to a solid stainless exhaust valve. He told me you weren't going to put a cam in it as well... Honestly, if you feel like you're going to want more power down the road, it would be a good idea to just get that done now.. I know you just bought the car though so money might be tight on that.

REDSEE5

Hey! Yep, he told me about AHP. I reached out to RPM this morning and they replied back stating “No, nothing is stock. We don’t usually carry any non-CNC’d cylinder heads anyway.”

Probably gonna stick with TEA. Thanks for the heads up, man.

REDSEE5

Alright so heads are at the shop. They are being done by Total Engine Airflow (TEA.) They are getting hot tanked, new powdered metal guides, Ferrea exhaust valves, and the factory intake valves are being sent to Del West to be tumble polished. Since mine is a 07 I’m also having them install their trunion upgrade. Total cost after tax is going to be $1200 for everything.

They said they are “anti bronze guides” because they are actually too hard?

Can anyone weigh in on the above fix and see if it is sufficient?

freddyvette

Depending on the iron content of the powdered metal (or sintered metal) composition, the hardness rating is anywhere from 40 to 70 HRC.
Bronze is marginally harder at 70 to 100 HRC

Titanium is less hard than steel, so the aim is to sacrifice the guide before the valve, therefore the choice would be PM or SM. With harder valve material, it's not as much of a concern.

The wear rate will probably be similar on both unless you're Dominic Toretto and live your life 1/4 mile at a time, and I would have the guides changed or inspected every 20k miles either way. Anyone who disagrees with that is a fool.

REDSEE5

Excellent. Thanks so much. I get on it about once or twice each time I take it out and do 4-5 1/4 mile passes per year so I’m hoping it will hold for many miles to come with such little track use.

freddyvette

Nobody has a failure proof solution, so I would enjoy the car while being vigilant, knowing it's not "one and done". That being said, I have about 30k miles on my bronze guide heads with the same valves you have at .650" lift.

MPeters1961

In another thread, a member posted that after talking to Katech, they stated the PM guides are a problem as they do not transfer heat away from the stems as well as bronze and it cooks the oil between the stem and the guide and then the stem turns into sandpaper. Has anyone else had this conversation with Katech? Does no one get their valves coated such as Katech's moly or with DLC to reduce friction?

freddyvette

That is a dubious explanation, since PM is a way better heat conductor

MPeters1961

Would you happen to know the expansion rate differences between the two materials? Since thermal expansion takes place, it would make sense one material would retain better clearance specifications during heat cycling. .

Katech_Zach

I don't know where they are getting this, but it is not a statement I have ever made. Maybe it's a misinterpretation of something else. There is nothing wrong with powdered metal guides, when machined properly and concentric to the seat. If there were, we wouldn't be building LT4s with stock guides.

Maybe they were misinterpreting what I say about improperly machined non-concentric powdered metal guides wearing and creating a slurry of powdered metal, chrome nitride, and oil the further accelerates wear.

MPeters1961

My apologies. I will look for that post when I get time. So, in your expert context, do you have an opinion/facts on which valve guide material would be more compatible with certain valve materials? I have read numerous times that bronze is a superior material for lubrication qualities. If valves and seats are concentric, it seems the other factor to eliminate excessive wear would be reduced friction with superior guide material and properly coated valves. Unless the geometry is so horrible, it creates sideloading. Once Katech fixes a set of heads, is that the end of this particular issue? Seems like many are experiencing repeated efforts and expenses to address this problem and I am wondering why. Thank you