Maxx_Z06

iTrader: (1)

Hey guys,

I'm swapping an LS7 into my C5Z pretty soon and everything is going smoothly.
The only thing i'm worried about was the LS7 exhaust valve issue so the shop who is doing my work here in Houston is going to install bronze valve guides and stainless steel exhaust valves.

They also added that the heads could be milled .030" for an extra fee... it would make a friendly pump gas compression at 11.7:1.

What are the pro's and cons on doing this? The exhaust valves and guides are are a for sure but i'm still a little skeptical about the milling.

Thoughts?

427zm

iTrader: (9)

Milling will add compression, which will add torque to an already torquey motor. Not sure what cam you're going with, but I can tell you my fathers heads after porting and polishing and exhaust valve "fix" were left un milled. He went with the Katech Torquer 116 and the combo made 525/477! And this is without headers! If you did the same setup w/ your 1 7/8"'s you could add 25-30 on top of that. Torque would be about the same, you may add a slight bit.

Milling will give you better throttle response, but I can tell you, from your stock LS6, this LS7 will seem like Superman! With a mild cam like the torquer, you will be adding more than 150 rear wheel! You won't believe how much of a torque monster that motor already is as well! Your tires will be getting a serious workout!

Maxx_Z06

iTrader: (1)

I don't mind the extra whp and torque
I'd just like to make sure there won't be any problems tuning this kind of setup along with the car running fine on pump 93 fuel.

Whistler

iTrader: (46)

Are you going to upgrade the camshaft? If so, I'd definitely try and get a little more static compression as the cam will drop the dynamic a bit.

427zm

iTrader: (9)

You should be fine working with 510. Personally, I wouldn't just b/c I've seen great results w/o milling. The other thing is, if you do mill, keep in mind a CC is lost every .006 you mill. So, .030 will cut down 5cc's which will put them @ 65cc's. a cam will change your dynamic compression, so you should be fine. Tuning shouldn't be an issue. The LS7 is a bad motor, it doesn't take much to make great power. You don't need a huge overlap pain in the *** to drive cam to make big numbers. The torquer 116 has put down 550 wheel pretty consistently, and the 110 puts down 565 pretty consistently. Both a pretty mild and good driver cams. The new Katech Kavorka out performs both and is supposedly a better driver cam than the 110.

Maxx_Z06

iTrader: (1)

Yes Im going to go with a custom grind cam and springs. Sorry I had forgot to state that. Can you elaborate some on what you mean by the added compression will drop the dynamic a bit? Trying to really comprehend this.

Maxx_Z06

iTrader: (1)

Im really leaning into Milling them since I probably won't be going with other heads on this setup. I did look closely at the Katech cams beforehand, but 510 suggested their custom grind cam that puts out very good numbers and has great street manners.

427zm

iTrader: (9)

Make sure they are running endurance lobes like comp LSL or LXL lobes. Reliability is much better than high maintenance.

Whistler

iTrader: (46)

When you change to a camshaft with more duration, specifically more intake duration, the intake valve closing angle (IVC) is later in the compression stroke. This means the upward moving piston travels farther before the intake valve closes, dropping your dynamic compression.

Raising your static compression by milling the heads will help with all over power and especially drivability, but be aware of your piston to valve clearance.

good2go

I had my LS7 heads milled 30 thou. I'm running the QM600 cam and this setup gives me almost 9:1 dynamic compression. Now the Torquer 110 and milled heads would move the dynamic compression to almost 10:1, way too much for today's gas.

Talk to whoever is specing your cam, he needs to know what you are doing to the heads.

427zm

iTrader: (9)

Are you sure of that? Pat and the team @ QMS do torquer 110's frequently w/ WCCH stage II heads milled 30 thou.

427zm

iTrader: (9)

I could see that w/ the 116 since it has "0" overlap, but the torquer 110 has 12* of overlap.

BTW, looks like the QM 600 made some mad power in your setup it looks like!

good2go

That's what the numbers work out to. I wouldn't do it unless I was running E-85.
"BTW, looks like the QM 600 made some mad power in your setup it looks like! "

thanks, it made 572 sae N/A. The 682 is with a 100 shot of N2O.

KCS

iTrader: (20)

Since the heads are going to the machine shop to have the valve issue addressed, you may as well mill them while they're there. Financially, it wouldn't make sense to pay the labor to have them taken off later to have it done. Are the heads being ported as well?

Higher compression helps make more torque, horsepower, and even better fuel mileage as long as the fuel can support it.

pontiac

iTrader: (4)

Is that exact math? I am trying to figure out /reverse engineer some specs from my LS7, and I know the Heads were milled but not exactly how much. But I do know the New tested chamber size is 63.5 cc's

so mine where milled .039?? probably .040 is what I am going to assume because the ".006 for every 1cc" ratio was rounded?


thanks ahead of time for the response.