SSMOKE

I drive my Z about 2K miles a year. Every time I start it it sees 6K RPM, but rarely more than 7K RPM. There are about 3K miles on my WCCH Stage II heads and I did a TORQUER 110 at the same time. All at around 10K miles. (560/511) I already headers, intake and a tune. Those three mods were done at around 5K miles, if I remember correctly. I will never measure my guides. IMO it is fixed. Even it is isn't, the joy/thrill that car provides me is PRICELE$$.

Mark2009

Holy Pot Metal, Batman!!!!

Curious, did they test the guide on the OD or the ID? May not make any difference, but ....

.... I've often wondered about PM guides, and this is probably a question for a metallurgist, but in the past I have run across sintered-iron parts in non-automotive applications and the conventional wisdom is to not machine or file on the outside of those parts since the 'hardness' is on the outside, not the inside. Supposedly.

Now a PM guide may be made with a different process, but I always wondered if machining the ID of the guide would not remove some of the hardness inherent in the unmolested external finish of the final product.

Alternatively, assuming the part in question was not treated with a surface hardening process (as those other parts I mention may well have been), and assuming the part was sufficiently heated to completely bond all the metal powder, then I suppose the hardness would be the same throughout.

Sure would be interesting to see that hardness test on the outside and the 'inside' (sectioned portion) of an OEM PM guide.

Turbo2L

The guide should be the wear item - not the valve stem. Just my opinion. YMMV.

Mark2009

Clearly it is an opinion. No one would be foolish enough to claim that as a fact, or to interpret it as a fact. However, as an opinion it is based on fact (widespread use of dual springs when beehives have clearly been shown to be superior).

Already asked, and already answered. And don't try to rehabilitate your argument post hoc by adding a "high horsepower" caveat -- this is the LS7 forum, not the alcohol dragster forum.

No, they have not. Man, you sure veered from taking me to task for stating 'facts' not in evidence

In fact, all the broken springs we've seen on this forum over the past several months are duals.

I doubt anybody on this forum has ever heard of a PSI beehive spring breaking. To claim that is not a great record is simply preposterous. It sounds like you are ....

.... living in the past

z76232

Thanks, you are a bunch of good guys. I used to have the other car and belonged to the other FORUM and they would have just crucified me. Mistakes happen.

The black bitch.

I got the sister head to that one ,I can somewhat laugh now. I'm not a wealthy vette owner,it really hurt me financially for a year. I still love the Z06 I don't want get this going AGAIN but I can't believe GM left us hanging out to dry ? Please I'm in no mood to fight

Unreal

Mark, that test showed in that case the beehive was better. I'm sure there are cases were a dual is better. Generalizing that beehives are superior, or duals, or whatever isn't correct. You pick what works for you application. Just like GM went from a Beehive to a dual spring for the new COPO camaros with the high revving motor option. I'm sure they did that because they chose a spring that was best for the cam/rpm/etc they are using.

When a beehive/lighter spring can control the valve, use that. When you need more spring pressure than a single beehive can provide, start looking at duals.

Dirty Howie

I had 25K miles and around 12+ track days on mine. They passed the wiggle test. Then shortly afterwards I decided to port them, port my intake and get a tune so I could keep up with my brothers who I track my car with.

So the guides needed to be replaced because of the porting but all the valves, springs etc were reused. They now have an additional 3k miles and 6 track days.


DH

telly444

I make good money and I am insane. my wcch will be here in 2 weeks. she goes in for surgery in 4 weeks. if I can make it another month I'm golden ( fingers crossed)

telly444

yup once this done on mine I'm not even gonna look at any thread that has the word valve or head in it. My car is fixed no wiggle nothing , road trips and possible 1/4 passes with a smile. I'm soooo done with the valve issue.!!!

Mark2009

I was not speaking of one test. I daresay you'll not find any test wherein a beehive can do the job that a dual is better (in valvetrain performance).

Generally speaking, that is incorrect

My information shows that a sodium exhaust valve and a PSI beehive is used on the new COPO Camaros (assuming that is even relative to the platform under discussion here): https://www.chevrolet.com/performance/copo-camaro.html

I will agree with your statement of the obvious. However, in the stock or mildly modified LS7 realm which we are discussing here a single beehive provides all the pressure that is needed. Unless perhaps you've employed a Rosie O'Donnell exhaust valve . . . .

Mark2009

Could you link us to those test results?

Dirty Howie

I will be happy to link you to the post where you requested that I in no way address you or respond to your posts.

I don't understand why you are unable to do the same for me and infact now ask me to address you.

As I'm sure you have advised other: The search function Is Your Friend !!!


DH

ATC399

No worries..18k on my 13Z stock heads..

AzDave47

Your lack of worries may be misplaced. One of the tech writers on this forum got new 2013 warranty replacement heads that from the factory had the valve concentricity with the seats in excess of the GM concentricity limit. If you still have the warranty, then don't worry, just get the heads checked before the warranty/extension is up.

My 09 with 47K miles had all exhaust valve guides and 6 of 8 intake valve guides beyond spec.

AzDave47

1100 miles on WCCH Stage 4 heads, P&P, K501 cam, Katech TiMo intake and new OEM exhaust valves. I will have the guides wiggle tested and probably replace the PSI 1511 beehive springs at 20K miles.

outhouse

If done correctly, no not at all.

ramairws6

https://www.corvetteforum.com/forums...l-is-good.html Mark2009 I see your still here ruining good threads

MUKAK

isnt MARK banned?

Dan_the_C5_Man

I assumed he grew tired of the un or under-informed "technical" posters, and decided to leave on his own.

If he was indeed banned, that was a mistake, and a loss for us all.