Cam Question

TheClassic · November 27, 2006

Just wondering if anyone knows what the lift and duration of the stock cam in the 5.3L of the '07 Classic is. I'm thinking about a cam swap. Thanks in advance.

99Silver6.0 · November 28, 2006

Just wondering if anyone knows what the lift and duration of the stock cam in the 5.3L of the '07 Classic is. I'm thinking about a cam swap. Thanks in advance.

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190/191 .466/.457 114

I think thats it.

TheClassic · November 28, 2006

Thanks. The cam I'm looking at is a Comp Cams piece. 218/218 .454/.454 The duration is about the same, but the lift is a lot bigger. How would that work out? Would I need pushrods and valve springs with that, or would I be okay with the stock components? Thanks again.

99Silver6.0 · November 30, 2006

Thanks. The cam I'm looking at is a Comp Cams piece. 218/218 .454/.454 The duration is about the same, but the lift is a lot bigger. How would that work out? Would I need pushrods and valve springs with that, or would I be okay with the stock components? Thanks again.

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That seems really, really small. You can run a Comp 212/218 .522/.529 or 216/220 .525/.532 safely. Youll be a good bit happier with the end result. Even the Thunder Racing "Old Man" cam is a good runner and makes good power with no sacrifice anywhere really. Good set of LONG TUBES will complement the extra dutaion and lift of a new cam.

svensk · December 6, 2006

Would that kind of lift rob low end torque? When you install a more agressive cam is it more of a "rob Peter to pay Paul" sort of situation?

TheClassic · December 11, 2006

Does anyone think a $97 cam will be worth it, or will it be any good? It's a Comp Cams High Energy Camshaft off Truckaddons.com.

99Silver6.0 · December 12, 2006

Does anyone think a $97 cam will be worth it, or will it be any good? It's a Comp Cams High Energy Camshaft off Truckaddons.com.

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Full cam specs will help on that decision.

In a stock 5.3, running stock stall. 216/220 is probably as high as I would push it or youll have crappy low end. Large cams wont make power until a bit higher in the RPM band. As long as you dont go crazy on the duration and lobe seperation youll be alright. Go to big, say with Thunders 224 on a 112LSA. Your gonna be hating the low end power. If you want to run stock stall, a good cam choice is Comps 212/218 .522/.529 114LSA. I RAN THIS CAM. It had good low end and pulled hard up to 6200 shift. You could even try the 206/212 they have. Would be even better on low end yet wont make quite as much power up high as the 212/218.

TheClassic · December 12, 2006

The ones I'm looking at are:

218/218 .454/.454

218/218 .485/.485

I know the lift on the first one is about the same, but the duration is way longer. And on the second one, the lift is a little bigger, and the duration is the same as the first one. The first one says "Small Chevy" and the second one says "Big Chevy." I'm assuming that just refers to the lift. Anyway, since the duration is the same, is that difference in lift going to make much of a difference?

Also, if I go with the first one, since the lift is about the same, would I be able to get away with leaving the rest of the valvetrain stock?

99Silver6.0 · December 13, 2006

The ones I'm looking at are:

218/218 .454/.454

218/218 .485/.485

I know the lift on the first one is about the same, but the duration is way longer. And on the second one, the lift is a little bigger, and the duration is the same as the first one. The first one says "Small Chevy" and the second one says "Big Chevy." I'm assuming that just refers to the lift. Anyway, since the duration is the same, is that difference in lift going to make much of a difference?

Also, if I go with the first one, since the lift is about the same, would I be able to get away with leaving the rest of the valvetrain stock?

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Duration numbers look alright. But the lift numbers are what get me. Im gonna have to look at that cam a bit more to see what lobe Comp ground that on. Im used to seeing the XE and XE-R lobes.

Stock cam being the first part to throw out. The stocker valve springs would be the second thing to pitch during a cam swap. It isnt the lift that makes them unfit IMO. With that new cam your gonna be revving alot higher than you did with the stocker. As the new cam will make alot more power up top. If you dont rev it up there you wont be taking full advantage of that cam. That said, you do not have to buy Comp valve springs if you dont want to. The Comp alternative would be the 918 springs. Or you can go the LS6 spring route. You can get a full set for around $80 bucks. I know this is a bad thing to do but Scoggin Dickey gets every bit of my OE GM parts business. Time and time again! Anyway, the LS6 springs can take .550 lift and will help stave off valve float that you might see with the stock springs at higher RPM's.

Third item to pitch would be the pushrods. They are thing, weak pieces of crap. Along with being too short!! If you want, Ill get into the pushrod explanations! Stock rocker arms are perfectly fine. Stock ratio is 1.7 and they are roller fulcrum rockers! If you want to throw on 1.8 or 1.85 ratio rocker id have to suggest you just get a bigger cam instead. Because in actuality thats what your simulating is a bigger cam.

TheClassic · December 13, 2006

Here's the page with the cams on it. Unfortunately, I don't see any info on the lobe. They also have some Edelbrock springs for $42 or $58. I know you shouldn't cheap out on something like an engine, but I'm thinking because of the name, they should be good parts. Anyway, I appreciate all your help. So far, you're the single most helpful person I've met here. Thanks.

99Silver6.0 · December 13, 2006

Ok. The link you posted is for SBC cams. Thats not an LSx grind. I thought those specs looked kinda funny. Plus I didnt even see it in my CompCams catalog. Im gonna post a link to Comps site that lists all the LSx grinds.

http://www.compcams.com/technical/Catalogs...-07/172-175.pdf

On another note, SBC valve springs will not work in the heads of your 5.3. Youll need Comps beehive 918's.

Comp 918 pic below. They made the uppermost portion of the spring smaller to reduce the mass at the keeper end. Less mass in that area means a lighter valvetrain. Thus a faster rev. Comp also makes a titanium retainer you can buy to further reduce the weight there. It isnt a big difference buy in this world of HP every little bit counts.