retarded stock cam?

[mdenz3]

Current setup:
1.9:1 rockers
LS6 valve springs and retainers
Removed balance shaft
Pace Setter headers
Herron Performance tune.
5spd, Al drive shaft, 3.42 gears

The car is my track toy (read road course) that I drive on the street whenever I haven't broken it. So what I'm mainly looking for is power from 3-6k.

With the rockers, springs and stock timing set I already ate through one dampener in less than 5k miles and i'm sure the other one is about done now. Hence, I have decided to go with a rollmaster single roller timing set. I figure with no plans to go with stiffer springs (though I may switch to comp 105's) and the biggest cam I'd ever run is the GT2, there was no need in the issues and cost of a double.

Which brings me to my pondering if whether or not I should retard the stock cam's timing while I'm switching timing sets. I figure a re-tune would be in order, but thats easily taken care of. I don't expect much gain, but anything above 5k would be nice, it just has no go up there now.

[Hib Halverson]

Re: retarded stock cam?

Once you go past 6000 rpm, the main limitation is the intake manifold assembly so, retarding the camshaft won't gain you much power but will kill mid-range torque which you need to accelerate off turns. As the most important turns on a road course are the ones which are at the beginning of straights, doing any thing which reduces mid-range is a bad choice.

[WarShrike]

Re: retarded stock cam?

What dampener are you talking about? Do you mean the chain tensioner on the timing chain?

I'd recommend going with a new timing chain and tensioner.

The biggest limitation is the Heads much more than the intake. Above 0.6" of valve lift, the airflow suffers on a stock intake/head combo (it actually degrades in airflow above 0.6" of lift). Stock heads by themselves flow about 160cfm at .6", while the stock intake causes about a 10% loss in airflow on those numbers at max lift.

Most stock engines are not going to run that much lift, but with your 1.9:1 rockers, you want to make sure that you aren't binding anywhere as our heads are only good for about 0.52-.53" of lift in stock form. Anything above that will require the valve guides to be milled or use modded retainers and viton valve seals.

If you're road racing this thing, that means you're probably running it up as much as you can in the rpms. If you are class racing and it is allowed, I'd recommend getting a different harmonic balancer as well. The stockers are supposedly good for about 6300 rpms, you could go with an SFI certified balancer by Powerbond or an ATI super damper. This might help cut down on the errant vibration from the balance shaft deletion.

[mdenz3]

Re: retarded stock cam?

Yes, I'm referring to the timing chain dampener/tensioner. It had a brand new timing set, that wore out in less than 5k miles. I intend to get the Rollmaster single to replace it and eliminate the dampener.

Currently I'm shifting around 5500 rpm because the engine simply doesn't make power above that. This is why I am considering putting the stock cam in at a 2-4 degree retard.

For lift I'm only running the stock cam, but If I did switch cams i would go back to stock ratio rockers.

[ssms5411]

Re: retarded stock cam?

What dampener are you talking about? Do you mean the chain tensioner on the timing chain?

I'd recommend going with a new timing chain and tensioner.

The biggest limitation is the Heads much more than the intake. Above 0.6" of valve lift, the airflow suffers on a stock intake/head combo (it actually degrades in airflow above 0.6" of lift). Stock heads by themselves flow about 160cfm at .6", while the stock intake causes about a 10% loss in airflow on those numbers at max lift.

Most stock engines are not going to run that much lift, but with your 1.9:1 rockers, you want to make sure that you aren't binding anywhere as our heads are only good for about 0.52-.53" of lift in stock form. Anything above that will require the valve guides to be milled or use modded retainers and viton valve seals.

If you're road racing this thing, that means you're probably running it up as much as you can in the rpms. If you are class racing and it is allowed, I'd recommend getting a different harmonic balancer as well. The stockers are supposedly good for about 6300 rpms, you could go with an SFI certified balancer by Powerbond or an ATI super damper. This might help cut down on the errant vibration from the balance shaft deletion.

Well said , might as well go with a cam if you want more lift. And do the springs and modded reetainers with V guides.