Will this cam work?

[96greenmachine]

I have a 1996 c2500, the engine is a 5.7L 350SBC(The L31) I’ve been doing some research and found a good deal on a cam. The part number from Comp cams is cl12-676-4. The specs are
230/236 @.050
110 LSA
.488/.501 lift
I know the lift is high for stock heads so I will be doing some springs, retainers, and 1.6 roller rockers. I’m just trying to see if anyone has any advice on whether or not this cam will work with the engine, or a better option for a cam. I’m not worried about the tuning because I’m going to do the 0411 PCM swap and have it tuned, but I am worried about whether or not the stock intake will be able to keep up with the new mods? Or if I should be looking to replace anything else while I’m doing the cam

 

[Komet]

That's coming up as a flat tappet cam for me, so no it won't work in an L31. I'd be looking for something under 220 @ .050 but still around .500 lift. Stock intake is pretty done at 5500rpm and you need torque production down low for heavy trucks. Roller rockers will provide extremely little benefit at this power level. You may need different length pushrods.

 

[L31MaxExpress]

That's coming up as a flat tappet cam for me, so no it won't work in an L31. I'd be looking for something under 220 @ .050 but still around .500 lift. Stock intake is pretty done at 5500rpm and you need torque production down low for heavy trucks. Roller rockers will provide extremely little benefit at this power level. You may need different length pushrods.

Full roller rockers are worth ~10 ft/lbs across the whole rpm sweep negating lift increases. Reducing the friction at the fulcrums reduces the torque it takes to spin over the engine. I have removed the stock GM stamped steel ones on cams with 0.480 lift and seen them almost worn completely through, under the pivot balls in less than 40K miles.

 

[Komet]

Full roller rockers are worth ~10 ft/lbs across the whole rpm sweep negating lift increases. Reducing the friction at the fulcrums reduces the torque it takes to spin over the engine. I have removed the stock GM stamped steel ones on cams with 0.480 lift and seen them almost worn completely through, under the pivot balls in less than 40K miles.

That's only 3% gains, the money would be better spent uncorking the exhaust first. But yeah, of course there's no downside to roller rockers, I just don't see the value on stocker iron heads.

 

[L31MaxExpress]

That's only 3% gains, the money would be better spent uncorking the exhaust first. But yeah, of course there's no downside to roller rockers, I just don't see the value on stocker iron heads.

Depends on the cam. To get to 0.500 lift most of the cams I choose need a 1.6 or 1.7 rocker ratio. I also tend to use less aggressive profile cams and more rocker ratio. It is easier on the lifters long haul.

 

[Scooterwrench]

I have removed the stock GM stamped steel ones on cams with 0.480 lift and seen them almost worn completely through, under the pivot balls in less than 40K miles.

Could some of that wear be caused by this all so great modern synthetic oils with no zinc additives?

 

[GoToGuy]

The oils are good. The zinc reduction has to do with cat converters and EPA, not the oil refiners. Just like low sulphur diesel is an EPA mandate.

 

[L31MaxExpress]

Could some of that wear be caused by this all so great modern synthetic oils with no zinc additives?

My money is more on the junk mexican built GM crate engine stuff. GM found those stamped steel garbage rockers failed in durability testing even on the stock 1996 LT4. They should have known better than to put them on a ZZ4 from day 1.

 

[Supercharged111]

My money is more on the junk mexican built GM crate engine stuff. GM found those stamped steel garbage rockers failed in durability testing even on the stock 1996 LT4. They should have known better than to put them on a ZZ4 from day 1.

It must be a very specific RPM that they take a dump at (and I do recall reading that GM said they galled on the LT4) because I'm forced to run them in my Camaro with stock LT1 engine/tune and they hold up. But then again we have to choke down to 260whp. I blued a bank of balls and rockers, but otherwise there wasn't a mark on them. I'm lucky if the oil stays 270 on a session, usually it's 300. Water runs 200-230.

 

[L31MaxExpress]

It must be a very specific RPM that they take a dump at (and I do recall reading that GM said they galled on the LT4) because I'm forced to run them in my Camaro with stock LT1 engine/tune and they hold up. But then again we have to choke down to 260whp. I blued a bank of balls and rockers, but otherwise there wasn't a mark on them. I'm lucky if the oil stays 270 on a session, usually it's 300. Water runs 200-230.

The ones on my TBI 350 Goodwrench were galled up very quickly. So it is not only rpm or even spring pressure. I am cleaning my shop at the moment and I may have a couple of those still kicking around. I like keeping man cave art of failed parts like that. I have a thrashed planetary set from a 700r4 and a piston on a bent rod too, lol. If I happen to find them, I will post pictures. The vans will run 275-300F oil temps too in the dead of summer without an oil cooler on them. I added the GM lines and used a 454 G-van radiator with the oil cooler built in on the 87 G20 I just built for that very reason as well.