jimmyz80

iTrader: (1)

I finally finished my heads/cam install on my Z06 and took it to get tuned. There's a nasty dip in the top end of the graph which is puzzling me. Does this look like it would be valve float?

Mods:
ETP 215 Heads 58cc
MS3 Cam
Kooks Headers
Stock LS6 Intake
Vararam
Comp 850-16 Lifters
Comp 8.050" Pushrods
SVO 42# Injectors

vettenuts

iTrader: (4)

Looks like spring surge, try shimming for more seat pressure if you have room to do so. Don't ask how I know

Those are also very long pushrods, you might consider the 3/8" diameter to minimize pushrod flex or possibly tapered pushrods.

02ZOh6

Looks like a lot of the graphs for etp heads but if you ask them it's not valve float. What springs did you get? 977's or the PSI's?
I have the 215's also but haven't dyno'd yet.
BTW, did you have to modify your alternator?

vettenuts

iTrader: (4)

The graph looks like it is recovering, spring surge would be my first suspicion.

jimmyz80

iTrader: (1)

What would be the recommended solution to spring surge? I'm not 100% sure on the springs, I'll need to check with the shop since they ordered them to be appropriate for my cam.

As for the alternator, I haven't modified it but i'm still working on a solution. For now I clearanced a valve cover to fit back on, and then unbolted a coil and trimmed the coil pack to fit back on. One coil is just hanging on with a zip tie until I can work out something or relocate them all.

02ZOh6

Jimmy, we moved my alternator out about an inch and everything fits fine. No cutting or hacking. The only thing is is that your belt will be too short and you'll have to get another one. I could shoot some pics for you. Another member did the same for me.

jimmyz80

iTrader: (1)

That would be awesome if you could post up some pics of the setup. Did you need to fabricate anything to move the alternator? What was the belt you ended up using?

vettenuts

iTrader: (4)

Depends on the setup. The easy answer is to shim the springs to get more preload, but you need to figure out all your spring parameters first (seat load, clearance to seal, type of springs/seals, coil bind, etc.)

02ZOh6

Yes we had to fabricate two pieces but nothing complicated. There's 2 bolts on the alternator and we left the top one in it's original position. This way it's hard to notice it's even been modified. If you put the top bolt in and try to push it down so the bottom one lines up you've already noticed it hits on the coil packs and that you're about an inch away from fitting. Well I had my brother make a sleeve for that bottom bolt as wells as a very simple bracket. The sleeve acts as a support for the alternator bracket. It's there so you can tighten the original bottom alternator bolt (alt. bolt runs through the center of it) without compressing the aluminum bracket and breaking it as well as your new small fabricated bracket. The smaller fabbed bracket comes off of the sleeve to the new alternator location. It is very strong and I've had no issues with it thus far. I believe my new belt length was 78.5" but I have an asp pulley. My stock belt was too long and my asp belt was too short so I had to find one in the middle.
I know it's hard to understand now but when I show you the pics you'll see how simple it is. I'll post them tonight.
Kind of sucks that we have to dick around with these heads after you shell out good money for them. For $30 ETP could have these parts made for us vette guys and save us some headaches.

redtail2426

iTrader: (10)

the only time i see this same exact dip is with etp heads..I wish somone would figure out what on these heads is doing it..My opinion is the longer pushrods needed for these heads are just deflecting too much.

redtail2426

iTrader: (10)

bump to the top,

02ZOh6

Here's some pics of the alternator mod. Let me know if you have any questions.

http://i106.photobucket.com/albums/m...DSC00334-1.jpg

http://i106.photobucket.com/albums/m...6/DSC00335.jpg

http://i106.photobucket.com/albums/m...6/DSC00337.jpg

http://i106.photobucket.com/albums/m...6/DSC00336.jpg

eamador11

on pushrods length. im surprised they fit with that much milling you did on the heads.

gojo

iTrader: (12)

http://forums.corvetteforum.com/show...ght=alternator
I made a spacer setup similar to the one Phil used except the brackets are thinner hard steel and the holes are drilled exactly 7/8 on center. I did not want any adjustment to be possible. Also 7/8 vs an inch clears the brake lines under the belt in front of the alternator. If you clamp the brackets together when you drill the holes they will be spaced right. The belt with an ASP pulley is a Gates K060780(78 5/8"). It's a Cad. CTS 2003 3.2L belt. Car Quest has them.
With regard to pushrods the 3/8's will not fit, except with Jesels, according to ETP. I ordered a set of Manton's 5/16 x 8.125 x .118 wall. They should be plenty stiff and that will give me between 3/4 to 1 turn on the rockers or .037 to .050 preload. ETP says more than that may be the problem. I had .062 to .075. with 8.15's. I'll take out 1/2 turn. I'm skeptical that I had too much, but we'll see.
If anyone has cured the problem let us know how.