I hate to be clichéd, but I need a little help and advice from experienced builders, unlike myself, regarding picking a cam. I've done a lot of reading, but I just can't seem to figure out exactly what cam I need.

I'm building a 5.3 that a buddy gave me to drop in my old truck. Like everyone else, I'm trying to squeeze out every bit of power I can with the stuff I've got. I plan on using a FAST intake and will be sending my heads off to have them port, polished, and bigger valves cut (not sure what size yet, so make suggestions if you will). I'll be keeping stock compression of 9.5:1 unless y'all think shaving the heads will boost compression.

As far as the cam goes, I want something choppy and as mean as they come. Driveability is nothing to me. It's going in a project truck, not a dailey driver. Sound and rumble is important. I've been shooting for 450-500 HP at the flywheel. I know it's a stretch, but the old man always said to aim high! I'll be mounting it to a t56, so I'm assuming stall is not an issue here.

With that being said, can any of you help me pick a cam and possibly explain why you chose it? I'm worried I will get caught up with high lift cams and pick something too big for my little ole 5.3. Thanks in advance. I'm here to learn, so please forgive any ignorance.

 

Call Kip at cam motion. Talk to him about getting something like his 212/216 stage two truck cam on a 110-112 lsa, instead of the 114 it has standard. He will set you straight.

Throw some ls6 hollow stem/sodium filled valves (2.00"/1.55") in your truck heads.

You could definitely deck the heads for compression up to 10.5-11:1, which would help you get closer to your goals powerwise.

Make sure you use the correct thickness head gasket for proper squish. And get some 1.75" headers, or bigger.

 

How much should I have the heads shaved? Is it really possible to hit 10.5:1 with shaved heads and a thin head gasket?

 

You can shave about 1mm off, drop the combustion chamber down to ~58cc, and use a thinner gasket. But, ultimately, the gasket thickness is determined by how much the pistons stick out of the block, to maintain proper squish. Static compression ratio takes a back seat to achieving optimal quench.

 

If you mill the heads to 57cc and retain the factory gasket thickness of .051" you'd end up right at 10.0:1 compression. I would recommend this for added torque and HP output.

Some more questions need to be answered though first before cam specs are given out.

How much does the truck weigh?
Rear gear ratio?
Tire size?
Trans?

 

I'm bolting a t56 six speed to it. The rear end is 3.73 on 29" tires. The truck weighs around 4000#

Should I be looking for a high lift cam or should I be looking more for duration?

 

Low compression and low displacement dictates less duration being necessary. Heavy vehicle is going to "want" a relatively early intake valve closing event for some early torque production, which also potentially limits the intake duration.

Lift is kind of dictated by the heads. If the heads stall after a certain amount of lift, then having more lift than that is just unnecessary valvetrain wear. You really want just a tad more lift than peak head flow, nothing excessive.

Honestly, you should not concern yourself with the sound of a cam. The camshaft is way too important to mess with just to get your engine to make noise. Get a small, well-matched cam, and pull timing at idle, and lower the idle speed to get the noise you want.

 

If I bump compression up to 10.8:1 with flat top pistons, shaved heads, and a thinner gasket, would that justify longer duration?

I didn't think about adjusting timing to roughen up idle. That's a very good idea.

 

The jump from 9.5 up to 10.8 probably would necessitate a little more intake duration, yes. Duration is so vague, though.

More static compression will need a later intake valve closing event to bleed off some of the cylinder pressure. Otherwise your dynamic compression ratio would skyrocket, and detonation would be imminent and unavoidable.

For the fuels us mere mortals have access to, dynamic compression needs to be well under 9:1, most shoot for 8.5 dynamic compression.

And be careful using a thinner gasket to bump compression. You need to set up the proper quench, more importantly than raising static compression.

Don't get me wrong, though. Raising the static compression ratio will undoubtedly prove to be beneficial in your case, but do so with flat top pistons and shaved heads. The gasket thickness will be determined by how much the pistons stick out of the block. Most people try for .035 - .045 squish, favoring the lesser.

 

Valve events are key, not so much duration and LSA. When you change the duration and the LSA of the camshaft and notice a gain in power, loss in power or change in where the engine makes peak power, it wasn't the change in duration or LSA that made the engine respond differently. It was the change in valve events.

So if we can pinpoint the valve events that will make the engine do what we want it to do for a given combo, we can get much more accurate when it comes to specifying a camshaft for the combination.

Here is what I would do:

224/228 .603/.595 112+2

I'd be glad to answer any other questions you might have here(might take me a couple hours or longer to respond) or you can call me/email me at the phone number or email below in my signature.

 

I got the motor tore down the other day. I was planning on having these heads machined, but they are damaged beyond repair. It seems the valve seat broke off and had a little fun bouncing around. The other side seems it suffered from detonation. That being said, I'm definitely looking for new heads and pistons now! Do any of you have suggestions?

 

Cheapest option that still constitutes as an upgrade is probably a set of 243's.

A set of stage two cnc ported truck heads is $1300 outright, $1100 if they will accept your junk as cores.

Tfs220 as cast heads from Brian Tooley for $2000.

Those are my suggestions, listed in order of price, not importance.

 

What's the purpose of the truck ? Daily driver, weekend toy , street/strip ?

 

A weekend toy mostly, but with a little strip use on the side. I'm trying to squeeze out all the power I can with what I've got.

 

I sell the As Cast 220's with a dual valve spring kit, powdered metal guides for stock rocker use and Ferrea stainless steel valves for 2075.00 shipped.

Normally I work with TEA on getting the spring installed heights and spring part numbers I want so that they work best with the camshaft being used. So that guesswork is also taken out for the customer.

 

What would my cheapest yet most reasonable route be? I originally planned to spend $1200 having the original heads worked.

 

Really the cheapest route is to try to find another used engine. You could get a 6 liter and pick up some displacement while you were at it. You should be able to find one for $800-$1200 depending on what your local market is like.

If you are going to buy piston and rebuild your engine, figure on about $1800-$2400 for the short block alone by the time you figure pistons, rebuilt kit and machine shop labor. Then you still need some heads.

If it were me, I would find a 6 liter used engine. Preferable an LQ9 for the higher compression.

When it comes to the performance formula, ported stock castings can be an excellent value with outstanding performance. Some ported LS6 heads will improve your compression on a 6 liter and add about 35-40 horsepower. They are cheaper than aftermarket castings. But, with that said, if you are on a budget, you might be surprised how much power a regular set of stock 6 liter heads can make when the engine is set up right. Don't assume you have to buy a set of heads to make good power and have fun.

With a 29" tall tire, more rear gear would be a huge plus. Some 4.56 or 4.88 gears would make a great performance upgrade and be especially helpful in letting your aggressive camshaft perform.

 

What would I need to hit 500 fwhp with an lq9?

 

Just a good 220s duration camshaft, a set of header and a good flowing intake. An LQ9 or LQ4 can make 500+ flywheel without breaking a sweat.

 

I don't need any head work? The stock heads are going to support that much?