Best cam

[Red_Rocket]

Just curious what cam would be good for a nice choppy idle for now on a stock l31

 

[Komet]

This will probably have some lope but also enough vacuum:

"Lil Chubs" Hyd. Roller Camshaft 1987-97 TPI SBC & LT1/4 – TPiS (TPI Specialties)

This cam makes a big lump of torque in the middle of the power band and still revs nicely to 6,000-6,500 RPM. Excellent for TPI and LT Street engines! 283/287 Adv. Duration 220/224 Duration @ .050 .500/.500 Lift 110 LSA

tpis.com

Too much lift for stock heads so it'll need the usual springs / retainers at least.

 

[Erik the Awful]

Chop, on a stock L31? Are you also going to throw on a set of Flowmasters, some chrome traction bars, and a "Panty Dropper" sticker? Sorry, couldn't resist, but that has strong poseur vibes. Duration and overlap will give you chop, but it'll ruin your gas mileage.

You really need a plan for your truck. What's the purpose? Cruisin' for dates? Spend your time and money on making the interior clean and comfortable. Racing? While we love these trucks, you're starting out with a handicap. Get something lighter or plan on serious modification. Daily driver? Bulletproof the charging and cooling systems and rebuild the suspension with an eye towards the ride quality. Invest in a nice stereo. Towing? Bulletproof the transmission, charging, and cooling systems, rebuild the suspension, and add tool storage.

If you're still wanting to up the performance - I can admit I built my engine for power - you'll really want to up the compression and do a pocket port on the heads. Then you'll need a good exhaust.

I'm running more lift than the cam Komet spec'd on a set of stock Vortecs. It runs great under 5000 rpm, and my transmission shifts before it goes any higher. Vortecs only take .480" lift unless you make some modifications. With LS2 beehive springs, Comp Cams 787-16 retainers, and umbrella seals instead of positive seals you can run up to .530" lift without having to cut the spring pockets.

My recommendation is to call your favorite cam company. They can spec a cam to suit your desires and your truck's purpose better than we can.

 

[Schurkey]

"Lope" screws-up off-idle performance. You're going backwards in performance, especially for a heavy vehicle with a medium-sized engine, and probably stock gears.

Don't get me started on the computer-tuning needed.

 

[Erik the Awful]

I should probably mention, you can tell my engine's cammed, but it doesn't lope hard. It does get mistaken for a big block. If you want sound, the exhaust matters more than the cam.

 

[400Rogue]

It's going to be impossible to suggest a camshaft based on wanting lope. And to be honest, lope is not what we want to focus on when selecting a camshaft. You will be far better off and much happier choosing a camshaft that compliments the use of your vehicle. We need to know how you want the vehicle to drive. So I'll ask a couple of questions from you. It's ok if you take some time to find the answers and then we can get to finding a camshaft that would suit your needs. Please let me know the following.

What is the primary use for your truck
I know you said stock L31, but have you done anything to the engine? Was it ever rebuilt, any bump in compression?
Any exhaust or intake modifications?
Tire size
final drive gear ratio. Is it 3.73 or 4.10?
Automatic or manual transmission?

Are you open to adding some other modifications alongside the camshaft? I would highly suggest it or you will likely be disappointed in the end result. At minimum I'd suggest doing some exhaust work.

 

[95burban]

Let’s not forget a good stall converter and gears to compliment the cam. @L31MaxExpress has a lot of experience in cams in heavy vehicles.

 

[400Rogue]

"Lope" screws-up off-idle performance. You're going backwards in performance, especially for a heavy vehicle with a medium-sized engine, and probably stock gears.

This isn't entirely true. We're really trying to optimize valve timing events to maximize work on the piston for given rpm ranges depending an a number of factors. Sometimes that results in a camshaft with a relatively tight lobe separation that will give us some lope, but also paired with the right lobe profiles provides a nice overlap triangle to work in conjunction with the pressure waves in the exhaust and intake runners.

 

[L31MaxExpress]

This isn't entirely true. We're really trying to optimize valve timing events to maximize work on the piston for given rpm ranges depending an a number of factors. Sometimes that results in a camshaft with a relatively tight lobe separation that will give us some lope, but also paired with the right lobe profiles provides a nice overlap triangle to work in conjunction with the pressure waves in the exhaust and intake runners.

It is absolutely true. Lope is misfire or atleast partial misfire. Hard to make torque when the air/fuel is not being completely burned every cycle. Bigger cams also typically have earlier exhaust valve opening too. Blowing the cylinder pressure out of the exhaust port while it still has substantial energy left to push the piston also kills low-speed torque.

 

[400Rogue]

I hear what you are saying, but I'm not going to be trying to maximize torque at idle. I care about the torque range where the engine is operating for a given application. Bigger cam is relative and says nothing about the actual lobe profiles or overlap. And if we are timing our valve events correctly to the pressure wave frequencies, a little lope is fine. Especially if we have a healthy compression ratio our vacuum at idle will be sufficient. If you want to improve torque, we generally want less exhaust duration for a NA application. But that means we may need a tighter separation angle to get to our ideal overlap, thus resulting in some lope.

A lot of aftermarket camshafts have more exhaust duration than intake duration. Even truck cams. But just for fun, what do you suppose would happen if we take the exhaust lobe and make the duration the same as the intake?