is it senseless to upgrade to bigger rockers if u plan on getting a bigger cam? i know a cam is more expensive and harder to install. but doesent it open the vales and let the engine breathe alot more? it directly affects the rockers by opening and closing them right? and is it necessary to buy any other parts if i buy a cam? i have someone to do the install

 

follow the link concerning rocker arm testing. I'll see if I can find the cam dyno results

http://www.easyperformance.com/Tech_..._Frameset.html

 

Long story short- yes, it is senseless to do both. I realize opening the valves further is better, however to make decent power gains with rockers- you really need to go for 1.9:1 (stock is ~1.6:1). Run the difference in lift on a stock cam, and you're good to go. Add in the extra lift of any decent sized cam, and you're way over what the heads can handle.

Some people do go with a 1.6 or 1.7 roller rocker for less deflection when using a cam, and less resistnce at the tip- but that is a lot of money for very little gain in lift.

There are enough cam choices out there that you should be able to get whatever result you're looking for with just a cam alone. You didn't mention doing heads anyways- so with stock heads, you're going to be fairly limited in terms of both lift and flow.

Yes- obviously you'll need all the gaskets (many companies offer a 'cam install kit'). Then, depending what cam you go with- you may need new valve springs (higher spring rate). If you go to a higher spring rate, you'll need a better timing chain too. If you're wanting to get a really large cam- add ported heads to that list too.

 

1.9:1 lifters are a quick and easy way to make your S/C'd engine breath better. A cam is better, but more work and more parts.

 

Add to the list of pros/cons:

You can pull so much more power out of cam than rockers, if installed/tuned properly.

Modified stock rockers don't really affect reliability.

Big cams have a habit of breaking timing chains.

There have been a lot of cases of high-rate springs breaking lately.

Like bumpin said, in order to take advantage of a big cam you will need to have head work done.

Install parts you will need to do a rocker change: new rocker bolts, valve cover gaskets (maybe, depending on mileage), coolant elbows (maybe, depending on mileage), oil, and coolant. Total cost of extra stuff: about $60.

Install parts you need to do a cam (assuming you're going for something bigger than the vs....s1x, or xp or bigger will require these): everything you need for the rocker install, plus....valve springs, valve seals, modified retainers, timing cover gasket, modified timing chain cover, aftermarket timing chain (read up on clubgp about this, or ask Keegan about his issues with his). Total cost of extra stuff: a hell of a lot more than $60. Most likely at least another $300.

Cams put out impressive numbers, but keep in mind that most of the people running big cams and making huge numbers aren't using their cars as daily drivers.
You can daily drive a cam'd car, and people do. Just make sure you know what you're getting into.

-Riggs.

 

I wouldn't want to drive a cammed car as a a daily driver. And as far as Keegan's car, I was somewhat involved with that situation, as I went to check on it for him a couple of times, and ended up driving it most of the way to him. I'm VERY familiar with that car. I had in my hand the double roller timing chain that broke due to improperly cut sprockets. I SEEN the damage done, and I know the cost involved in that repair. MAJOR damage done, and I'm surprised the engine was even saved. 336 WHP! Freak accident, maybe. All I can say about that is the timing chain manufacturer AND ZZPerformance made it right with Keegan, as fair as they could. And I applaude ZZP for doing that. The bill for the repair was just under $2,000. AND THEN, he breaks a hardened input shaft in the transmission, that is supposed to be unbreakable! THAT was a race tranny.

And THAT is why Keegan sold off ALL of his mod parts, and has or is putting it back to stock.

I myself have broken 2 flex plates. The 1st was with a stock engine, and the 2nd one I twisted the center out of.

Maybe I'm getting of subject, but the point is if you want your L67 to breath a little better, add the 1.8 or 1.9 rockers headers, N*Star T.B., and all the other related goodies. If your going to race the car, expect it to break. You can't reliably use 400-500 BHP on the street in a FWD car, nor get any milage. Stick with the rockers. With all the related goodies to go with it, including bigger injectors, you should be around 350 BHP, and that ain't shabby! Add an intercooler, ported blower and intake and a smaller pulley and your flirting with 375 BHP or more. NO CAM!