Mgpeagle

iTrader: (6)

Does anyone know the stock specs for the LS4 cam? I did do a search and could only find guesstimates. Thanks in advance.

-Mike

neilownz

http://www.gmtuners.com/LS4/index.htm

That's the only info I have ever found.
But I thought compresssion was higher than 9.9...

06 SS

Roller cam profiles are about the same in stock applications (similar lift for similar duration across the board). With a .490 lift in/ex, we are probably looking at a duration of 207/207@50 As to an LSA, GM likes to keep the overlap on all their LSx engines about the same. Numbers work out to be around a 116 LSA. Which would give a pretty smooth (low, non-peaky) torque curve over a wide RPM range.

Obviously not a measured value, but it should be very close.

Mgpeagle

iTrader: (6)

Cool, thanks guys. I want rockers and wanted to know how much lift we had already. Thanks for the replies.

-Mike

Ill_Born_ss

If it is of any help, the stock cam has:

Lift: Non DOD lobes 0.283" intake and exhaust
Lift: DOD lobes 0.289" intake and exhaust

Valve Lift: Non DOD 0.482" intake and exhaust
Valve Lift: DOD 0.490" intake and exhaust

Mgpeagle

iTrader: (6)

Thanks man.

Also, since we have LS6 heads on these cars; do we also have LS6 springs too? Thanks in advance.

-Mike

Ill_Born_ss

Our ls6 heads are the small valve heads due to the smaller bore, the real ls6 heads will only fit if you bore it out 0.30 oversize or bigger.
As for the springs unsure due to different pn`s available for ls6 springs.

Mgpeagle

iTrader: (6)

Thanks Ill Born SS.

I have decised to go with these rockers. I am also going to get some oil restricted pushrods too just to be on the safe side. Let me know what you think?

http://www.byunspeed.com/product_inf...d738cbd5ed0493

-Mike

Ill_Born_ss

The rockers look and sound decient,I personally would not change the pushrods with anything but possibly a larger diameter for extra strength only,(no change in oiling or length) due to DOD/AFM and the engines natural lower end prority oiling, built right into each engine.

I noticed in your sig that you have 1.9 rockers installed, so I bring this to your attention:
Stock valve train operates on 1.7.1 rockers which gives you a lift of .482/.490
Your new chioce operates on 1.8.1 rockers which gives you a lift of .509/.520
The installed choice operates on 1.9.1 rockers which gives you a lift of .537/.549

The max stock lift for the installed spring/valve combo is .525 with an installed spring height of 1.8"

The LS6 beehive or Hi/Po springs as far as I can see require a longer valve to be installed to give a max lift of .625

Then you have to check valve to piston clearance.

hope this helps

06 SS

He has the 1.9's on his V6 per his sig.

Mgpeagle

iTrader: (6)

Yeah, my GTP V-6 has the 1.9's on there. I am going with 1.8's on the GXP. I am getting some oil restricted pushrods to prevent any valve float I may get. Just for insurance purposes... I also have my DOD shut off, I hated it! lol... After that, I am just porting the intake and exhaust manifolds and maybe get a heat soak reduction kit and I am done modding the motor. There isn't really anything else I can do bolt-on wise after that. Unless I turbo it and I won't due to the cost of it. After all is said and done the car should be in the 12's somewhere, hopefully.

-Mike

Nacho SS

iTrader: (4)

Question Mike, kinda random, does your catless DP rasp like a mothertrucker?

Mgpeagle

iTrader: (6)

No, I have no issues with any rasp. I did however have an stock exhaust tip sound raspy because the inner pipe and the chrome tip piece were clinging together but I remedied that. FWIW, I clipped a very small piece of stainless steel clamp and tapped it in between the chrome tip and the inner pipe with a small flathead screwdriver. You can't even see it. No more raspy, clanking noise. I think it sounds bad a$$ now. My friend tells me it sounds like a Mustang with a nice exhaust. I guess I can't complain.

-Mike

Mgpeagle

iTrader: (6)

Ill Born SS,

Any idea what a 1.85 would give me for lift? Thanks in advance. I may be getting a great deal on SLP 1.85's this is the reason I am asking.

Don't know if this is correct but my calculations come out to .523 and .533. I think I will still be safe if I use some oil restricted pushrods.

-Mike

Ill_Born_ss

Well like I explained earlier, GM has a max limit of .525 for a reason on the stock valve/ spring combination.
You could try and measure the actual on your engine but you can only guess what the actual is hot and really hot.
The 1.8`s put you up in lift and still remaining within the middle 80% of installed travel and as mentioned earlier the pushrods for this engine do not need the reduced oiling.
Some oversized dia. or good same spec. cro/moly rods will more than suffice.

Mgpeagle

iTrader: (6)

These are the pushrod's I want: http://intense-racing.com/Merchant2/...LSx_Valvetrain

I don't beat the hell out of the car so I think I'll be Ok. Correct me if I am wrong but .525 to .533 is not too much of a difference is it?

I currently run the 1.9's on the V-6 with stock springs and pushrods and have had no problems for about 60,000 miles.

Thanks for all the help.

-Mike

Ill_Born_ss

Yes I have no doubts of the Pushrods or their quality.
As for the comparision of the V6/V8, you can`t just do it that way. The dynamics of the camshaft alone should raise your brow. 4 cylinders with .283 and 4 with .289, again the only true and inexpensive way to tell is pull a cover and a plug and physically measure.
.001" hitting a piston is HELL!

Mgpeagle

iTrader: (6)

Wouldn't these be worse for valve float since they are 1.9's?

http://www.zzperformance.com/grand_p...=953&catid=104

Believe me I am not doubting you; I just don't want to change the darn springs...

Thanks man.

-Mike

neilownz

Someone said the quality of those didnt look consistant and they sent them back.

MCSS07

So what is the best setup for Rockers on the LS4 cars?

1.8 or 1.85?

110lbs Springs or 130lbs springs?

5/16" Oil Restrictive or 3/8"?

Anyone tried these yet? http://www.vincihiperformance.com/impalassMAINPAGE.html