GT3 and Spring Load

[Darkshadow188]

I'm looking into Abbott Stage 2 heads but notice they use 130# valve springs. I was at ZZP looking at 130#ers and it said that I should use Double Roller Timing with those springs. Im torn between GT2 and GT3 cams to match the heads and intake from abbott. Which would you reccomend(Over time I'd like to see 1.5 to 2 hp per cubic inch @ 231ci). Should my rpm range jump to 7k? The specs for the Gt3 cam are:
224°/224° at .050"
Intake Lift .335" (.536" lift at 1.6:1 rocker ratio)
Exhaust Lift .335" (.536" lift at 1.6:1 rocker ratio)
113 LSA
Are there advantages to a double roller timing kit? I've read up on it but didn't quite understand about the removal of the balance shaft. Are there pro's and cons to removing the balance shaft when making that much power?

[Darkshadow188]

Forced induction is much later down the road. I forgot to add that.

[AZ3.8Camaro]

Double roller is recommended because stiffer valvesprings put a lot more load on the timing chain.
The most common problem is the tensioner goes bad fast.
The double roller is much more resistant to stretch and allows you to remove the tensioner. You also will have to remove the balance shaft to run it because it is twice as wide as the regular chain, the sprockets are wider and would hit the gear the drives the balancer shaft. You can either remove the gear, or remove the whole shaft, its up to you, depending on if you have the engine out of the car or not.

HOT TIPS: Nice choice on the cam. I was just remarking an how I like the 224 duration. You will need the valve guides milled down to run that cam, but if you are getting abbott heads, I would do one of the following:
1)Run 1.7 rockers to get more lift to work with the improved flow. Make sure they mill the valve guides.
2)I would get a cam custom ground from comp with that 224 duration, probably an extreme energy that gives you more lobe lift. You need closer to .600' lift to work best with the heads.

REALLY HOT TIP: If you want to run 7000RPM, I would bump the lobe sep down to 110. Install at a 108 intake centerline.

[ September 29, 2005, 01:29 AM: Message edited by: AZ3.8Camaro ]

[blacksport]

I have abbott stage 3 heads on my car. I'm considering changing cams.


I was wondering what the down side to swapping out for some 1.7 roller rocker would be.

My valve guids have been cut down to handle .600 lift. I don't want my powerband to start to crazy.


1.7 ratio would put me at .538 lift. Or would i be better off swapping out a cam for one with more duration?

[98Camaro3.8]

I run 1.7 rockers with my GT2 cam. Not huge, but I think I can see the difference at upper RPMs.

[AZ3.8Camaro]

Head with more flow up in high lift areas will make more power with a high lift cam.
The point of the GT2 cam is the lift is dead nuts with the stock heads. It is a comp cams 4x4 grind, meaning it has the fastest ramp rates but lower lift. The extreme energy would be a better choice for ported heads that can handle the lift.

1.7 rockers will help you. The lift is still fine. It could be higher, but it will work fine. Just make sure that you get valvesprings to handle it.

[Darkshadow188]

Any pros and cons about removing the balance shaft? I think the engine is coming out of the car because Im going to have the pistons redone to handle the extra power. So what is best for my application, removal of the Balance shaft or just the gear.

[AZ3.8Camaro]

If you remove the shaft, you will need to plug the oil hole for it.
If you remove the gear, nothing else has to be done.
The only disadvantage of just removing the gear is that you are still lugging around the weight of the shaft.

The disadvantage of removing any part of it is that your engine will shake more. Noticably more.

[Darkshadow188]

Would either one of them require th 50% balance on the rotating assembley?

[AZ3.8Camaro]

Doesn't matter. The motor will always shake if you put a one million dollars worth of balancing and parts on it. Its related to the firing order and 90* v6s. The balance shaft cancels out secondary vibrations, which cannot be balanced out of the crank rods or pistons.

[Darkshadow188]

Does anyone know the formula to calculate lift? Im deciding on 1.7 rockers with teh gt3 or not.

[WickEdSix9838]

Originally posted by Darkshadow188:
Does anyone know the formula to calculate lift? Im deciding on 1.7 rockers with teh gt3 or not.

lobe lift times the rocker ratio.

[Darkshadow188]

I am slightly retarted when it comes to cams, but how do I find the lobe lift of a particular cam? Is there a formula for that too?

[Darkshadow188]

Scratch that I figured it out.

[Darkshadow188]

Woa! Ok so with 1.8 rockers that puts me at .603 lift and 1.7 rockers put me at .5695. At what point would I have clearance issues with the pistion(assuming I use the Abbott heads)? What other issues might I run into(other than the intense vibration from the cam and the standard SES light that will be programmed out.)