Best cam for stock L31?

[96greenmachine]

I have a 1996 c2500 that I’m building and I’d like to put a cam in it. I Already plan on doing the 0411pcm swap so I’m aware it’ll need to be tuned. I’m looking for a cam to run with the stock engine that will increase the power, and make it sound like it’s cammed at idle. Any recommendations?

 

[Erik the Awful]

If you're looking for sound, spend the money on mufflers instead of a cam. Buy a pair of these and start getting tickets for noise.

Cherry Bomb SA1229 Cherry Bomb Salute Mufflers | Summit Racing

Free Shipping - Cherry Bomb Salute Mufflers with qualifying orders of $109. Shop Mufflers at Summit Racing.

www.summitracing.com

What is your plan for the truck? It's a 3/4 ton, so it's not going to be fast. Do you need the power for towing? Or are you just wanting the truck to be more fun to drive? How important is fuel economy?

 

[96greenmachine]

If you're looking for sound, spend the money on mufflers instead of a cam. Buy a pair of these and start getting tickets for noise.

Cherry Bomb SA1229 Cherry Bomb Salute Mufflers | Summit Racing

Free Shipping - Cherry Bomb Salute Mufflers with qualifying orders of $109. Shop Mufflers at Summit Racing.

www.summitracing.com

What is your plan for the truck? It's a 3/4 ton, so it's not going to be fast. Do you need the power for towing? Or are you just wanting the truck to be more fun to drive? How important is fuel economy?

More fun to drive, fuel economy is of no importance to me. I’m not really looking to set a record for my 1/4 mile times.

 

[L31MaxExpress]

Any cam change really needs springs and a tune.

Any cam that sounds like a cam is going to trade off low-speed torque and be more difficult to tune with the black box.

 

[Erik the Awful]

My usual response is "Call your favorite cam company and ask for a cam."

Any cam that sounds like a cam is going to trade off low-speed torque and be more difficult to tune with the black box.

I called Lunati and got their 20080720. Big lift, moderate duration. With the Cherry Bomb Salutes you can definitely tell it has a cam, but even the low speed torque is much better than stock. It definitely requires a tune, but it ran decent with the factory Vortec injection before I yanked it out of my Suburban and put it in WCJr.

Any cam change really needs springs and a tune.

Yup. Don't go up in cam size without new springs.

 

[The_Family_Tahoe]

I have a 1996 c2500 that I’m building and I’d like to put a cam in it. I Already plan on doing the 0411pcm swap so I’m aware it’ll need to be tuned. I’m looking for a cam to run with the stock engine that will increase the power, and make it sound like it’s cammed at idle. Any recommendations?

Sounding cammed at idle with a truck is a bit contradictory because trucks need low end torque. Large intake duration is needed to sound cammed and that same duration kills low end torque. Anyway...
Do it!
If you're running an L31, bump up the compression ratio and run a Summit cam. They offer a GM hotcam clone with 218 of intake duration. Use that cam with some beehive springs. Get a pcm tune. With a 2500 chassis you must run a stall converter in the transmission that is higher than stock. Look for a 2500 ish stall speed.
Make sure the axle ratio is 4.11 or higher numerically.
Or just run the stall converter with the higher numeric gear ratio. It will be a blast to drive vs current state, guaranteed!

 

[L31MaxExpress]

Sounding cammed at idle with a truck is a bit contradictory because trucks need low end torque. Large intake duration is needed to sound cammed and that same duration kills low end torque. Anyway...
Do it!
If you're running an L31, bump up the compression ratio and run a Summit cam. They offer a GM hotcam clone with 218 of intake duration. Use that cam with some beehive springs. Get a pcm tune. With a 2500 chassis you must run a stall converter in the transmission that is higher than stock. Look for a 2500 ish stall speed.
Make sure the axle ratio is 4.11 or higher numerically.
Or just run the stall converter with the higher numeric gear ratio. It will be a blast to drive vs current state, guaranteed!

Stock B82 Small Block 4L80E converter stalls around 2,400-2,500 rpm.

Overlap is what makes the idle sound cammy not so much duration. I can spec a cam that will lope like crazy at 550-600 rpm and make more torque than the stock cam by ~1,500 rpm. The old Crane 274H06 was one such cam. It was ground on a 106 LSA and 102 ICL it had a choppy idle and was a stump puller even in a low compression 305.

 

[The_Family_Tahoe]

Stock B82 Small Block 4L80E converter stalls around 2,400-2,500 rpm.

Overlap is what makes the idle sound cammy not so much duration. I can spec a cam that will lope like crazy at 550-600 rpm and make more torque than the stock cam by ~1,500 rpm. The old Crane 274H06 was one such cam. It was ground on a 106 LSA and 102 ICL it had a choppy idle and was a stump puller even in a low compression 305.

What does this hypothetical cam spec at .050 for an L31 and what would you recommend as the hypothetical pump gas compatible static compression ratio?

 

[L31MaxExpress]

What does this hypothetical cam spec at .050 for an L31 and what would you recommend as the hypothetical pump gas compatible static compression ratio?

206/212 @ 0.050 on a 104 LSA and 100 ICL. Stock compression as the IVC is only 1.5° later than the stock cam. I would put 0.016" steel shim gaskets on it for the quench improvement. The overlap is increased from -28.5 to 1. The exhaust valve also opens at factory evo point so you will not blow down the cylinder early either which cost low-speed torque. The cam in my high compression 383 only has 5° overlap and it is very thumpy idling it down to 550-600 rpm. This is not a cam you would want to run with exhaust manifolds and restrictive stock exhaust. It would want headers and a free flowing exhaust for scavenging. I would use headers, 2.5" pipes, high flow bullet cats, and a 2.5" to 3" merge Y with a 3" straight through muffler like a magnaflow to maximize scavenging. At light load it would also misfire and carry on until 1,200-1,500 rpm but would be a stump puller at WOT from 1,500-5,000 rpm.

 

[L31MaxExpress]

At some point I am actually considering changing the exhaust setup on the van. It has always had dual 3" off the manifolds to the muffler. The Thorley tri-Ys have 2.5" collectors. I am considering 2.5" pipes off the headers into a dual 2.5" to single 3.5" merge Y to increase exhaust velocity and scavenging. That setup will help keep the exhaust hotter which aids in velocity and removes 30 lbs or so of metal. I would also get rid of the heavy chambered UltraQuiet muffler and put a straight through 3.5" long case magnaflow on it. I would also change to a Nascar boom style exit in front of the passenger rear wheel because I like the look and sound.

If I do this setup it will have a Speed Engineering X-pipe before the cats and the merge Y after the cats to equalize the backpressure caused by the cats and to get maximum flow through the cats. I will V-band the headers at the same time. The Thorley flange arrangement sucks because of the orientation they welded the flanges at. Just a hypothetical exhaust system I have dreamed up to get more from the current engine.

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