Is Marine 395 cam the right one for '98 DD K2500 L31

[homeslice]

Hey Guys,

Wanted to ask a quick question about the 395 GM cam. Based on all the previous posts I've gone thru, it sure looks like this '395 cam is the one to go with for all around performance/mileage/towing. The other cam I was looking at is Comp Cams 08-409-8. The Comp cam has more duration @0.050", and a bit more lift. That said, it sure looks like more folks prefer the '395 over any other.

My question is this (or these) - Noticing that the '395 cam has an advertised duration of 288/308 and @0.050" of 196/206 - it appears this cam has 90 degrees more duration under 0.050" than damn near any other cam in its class. Is this additional duration under 0.050" what gives this cam its magic ?

Last question - Given this setup, what cam would you install ? -- '98 K2500 - 8 lug - 4L80e - Stock TC - 3.73 - L31 - 0411 pcm - 24x cnp ignition - shorty headers - K&N CAI - upgraded delphi Spider injectors. I plan on upgrading valve springs to Comp 26918, 787, 648

Thanks

 

[JeremyNH]

I have a 1998 K1500 with the 395 cam - 4L60e - stock TC - 3.73 - L31 - 0411 pcm - 24x cnp ignition - shorty headers - Volant CAI - marine intake. I also installed Elgin 1.6 stamped steel rockers and upgraded to the comp retainers with LS6 beehives. Post everything dyno 212 rwhp@4560rpm, 278 rwtq@3500 rpm. Truck runs great, slight lope, slight improvement in mpg. I don't know where I started but stock I believe typically runs 180 rwhp/230 rwtq. I spoke to comp cams and they recommended the 08-500-8 cam as a competitor to the 395 cam so maybe you want to consider it. I considered it but thought the ramps may affect longevity of the valve train so stayed with the 395. That was my experience and the extent of my knowledge.

You may want to consider the 26915 springs instead of the 26918 unless you're planning on changing out the press in studs as well. The 26915 springs are stiffer than the LS6 springs and far stiffer than L31 stock. LS6 springs are less than half the cost of either though. Food for thought.

 

[homeslice]

I tried LS6 springs, and the ID of the lower portion of the spring (big end) was too small to fit around the valve guide boss on the vortec heads. it would fit, but it was like an interference fit; so I did not use the LS6 springs. The 26918 springs fit perfectly around the valve guide boss and also fit nicely in the spot face machined into the head. The only downside I saw was that installed height of the 26918 springs was generally about 1.75" on my vortecs, whereas design installed height is 1.800".

From what I've read elsewhere, the 26918 springs don't require threaded studs; as I've not heard of pressed in studs pulling out.

Not really wanting to pull my heads off the engine just to enlarge the pushrod hole to enable 1.6 rockers. Looks like its worth about 10% performance gain tho.

 

[Supercharged111]

I yanked the heads for 1.6s. It sucked, but with the heads on the pushrods we're rubbing. I also did the marine cam and was pleased with the performance after. Felt like stock, but more power everywhere.

 

[JeremyNH]

I tried LS6 springs, and the ID of the lower portion of the spring (big end) was too small to fit around the valve guide boss on the vortec heads. it would fit, but it was like an interference fit; so I did not use the LS6 springs. The 26918 springs fit perfectly around the valve guide boss and also fit nicely in the spot face machined into the head. The only downside I saw was that installed height of the 26918 springs was generally about 1.75" on my vortecs, whereas design installed height is 1.800".

From what I've read elsewhere, the 26918 springs don't require threaded studs; as I've not heard of pressed in studs pulling out.

Not really wanting to pull my heads off the engine just to enlarge the pushrod hole to enable 1.6 rockers. Looks like its worth about 10% performance gain tho.

Fair enough. I'm not making any recommendations just wanted to tell you what I did in fact do and how it did in fact turn out. With regards to the rockers I'd be surprised if it added more than 2hp to the rear wheels but I hadn't worked on a motor since high school shop 30 years ago so actually wanted to pull the heads. I didn't find it difficult. Nerve wracking but not difficult. My mods all went well though so only advice I would have on your build is that if you use the EFI Connection coil mounts and if your truck has AC the #1 coil won't mount in its' intended position because the AC compressor pressure switch harness sticks out too far. I stacked the #1 coil on top of the #3 using 1.5" spacers and longer bolts. The EFI Connection wire harness reached perfectly so it was a no added time $5 fix. The only thing I would have done differently on my build was to keep the exhaust manifold on and not put in shorties. I dread having to ever replace the #8 spark plug given that it's hard just to get the plug boot off. But I put in new Denso Irridium plugs and only drive the truck maybe 2k miles per year so hopefully will never have to.

The aim of my build was reliability with moderate improvement to performance based on modernizing vice hotrodding the motor and I believe I achieved that. But with reliability only time will tell.

 

[homeslice]

Undersand totally, thanks for the feedback. Yep I like how you stacked the coils on driver side, thanks. This truck came with the shorties, which I may just do away with and slap on some longtubes.

I may just pull the heads to drill out the pushrod holes and use 1.6 rockers. Did you go back with the .028" compressed thickness head gaskets to get a CR bump ?

 

[JeremyNH]

I used the standard GM gasket GM #10105117 which has the 0.028" compressed thickness. Something to be aware of is if you pull the heads you'll get a cup or two of coolant squirting out the rear most short head bolt from both heads when you remove them. I had the manifolds off when I pulled the heads and immediately stuck a sock in each of the exhaust pipes for fear that I would drop something down them. If not for the sock most of the coolant on the drivers side head would have gone down the exhaust pipe since the stream hit it direct.

 

[L31MaxExpress]

I was not a fan of the 395, not worth the money for the cam, time, effort or gaskets to install it. Get something a little bigger like the XM262 or XM270. Yout truck will not pull uphill in OD regardless of the cam. At 3,000 rpm MOST cams will make signifigantly more power than the 395 and if it ever downshifts to 2nd at say 4,000 rpm the power of a slightly bigger cam will be vastly superior. Stock 96 LT4 cam at 203/210 duration advanced 4° with 1.6 rockers had alot more beans than the 395.

 

[L31MaxExpress]

I have a 1998 K1500 with the 395 cam - 4L60e - stock TC - 3.73 - L31 - 0411 pcm - 24x cnp ignition - shorty headers - Volant CAI - marine intake. I also installed Elgin 1.6 stamped steel rockers and upgraded to the comp retainers with LS6 beehives. Post everything dyno 212 rwhp@4560rpm, 278 rwtq@3500 rpm. Truck runs great, slight lope, slight improvement in mpg. I don't know where I started but stock I believe typically runs 180 rwhp/230 rwtq. I spoke to comp cams and they recommended the 08-500-8 cam as a competitor to the 395 cam so maybe you want to consider it. I considered it but thought the ramps may affect longevity of the valve train so stayed with the 395. That was my experience and the extent of my knowledge.

You may want to consider the 26915 springs instead of the 26918 unless you're planning on changing out the press in studs as well. The 26915 springs are stiffer than the LS6 springs and far stiffer than L31 stock. LS6 springs are less than half the cost of either though. Food for thought.

Bone stock junkwrench 5.7L/4L60E/3.42 8.5 g80 in my 97 Express made 185 hp and 250 tq. With the 395 marine cam, 1.7 rockers, 2.02/1.60 valves in early canadian 906s (242 cfm @ 0.500 compared to 210 @ 0.500 on the junk hecho en mexico 062 crate engine heads), heads milled 0.020" on 0.016" shim gaskets, marine intake, thorley tri-ys into the factory dual 3" exhaust to a dual 3" in/4" out bus muffler, and march underdrive pulleys using 24x 0411 and D585 coils made 230 rwhp @ 4,400 and 304 rwtq @ 3,400 through a 4L85E and 3.73 9.5 14-bolt. The machine shop friend of mine that setup those heads used 0.100 longer valves and stock Z/28 springs, only 55# on the seat! Valve float before 4,500 rpm. I swapped to Pac1218s on Comp 787 retainers with 0.050" shims under the springs. No other changes, 257 rwhp @ 4,900 and 310 rwtq @ 3,100. Then tuned it on E85. On E85 with the timing at 34° total from 2,400 rpm it made 272 rwhp @ 4,700 and 330 rwtq @ 2,900. There were places in the powerband E85 tuned made 40-50 ft/lbs more torque. Swap to a Lunati Bare Bones 218/228 on a 112 LSA with 1.6 rockers for 0.536 lift. 290 rwhp @ 5,200 and 340 rwtq at 3,000 with the same torque as the 395 down at 2,500 (2,800 stall speed but locked converter, 2nd gear pull). From 2,500+ the 218/228 made more beans. Then before the 5.7L badwrench nearly destroyed itself, I put Assault racing 205cc heads with a little sanding roll cleanup and a decent valve job on it. The heads were flowing 265 cfm @ 0.500 through a 2.02 valve. With a 0.028" stock head gasket it made 312 rwhp @ 5,500 and 350 rwtq @ 3,400 with torque unchanged from 2,500. Really took off with the aluminum heads around 3,000 rpm.

 

[L31MaxExpress]

This is before the spring upgrade and E85. Wish I had an after. Also wish I had taken an after with the larger cam, aluminum heads and the 5.13 gear set on the 9.5. Going from 3.73 to 5.13s made more of a difference than the engine mods did from stock to 312 rwhp, then again that engine wanted gears badly with its ability to breath easily past 6,000 rpm.

This was right after startup and no tune tweaks yet.

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After some tweaking, had a 2,800 stall but the tune needed a little work still. Had to add more AE after the converter because it wanted to lean pop when you jumped on it from a stop. That was actually a lean pop back into the intake on the 1-2 shift.

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