L31 towing cam upgrade

[kylenautique]

I'm going to be installing a new L31 block in my 98 silverado to replace my tired stock engine. My truck does lots of towing and hauling. Is there a better cam for towing over the stock cam? I know the vortec heads are somewhat limited to the lift you can add without modification, and I don't really want to modify the heads. Just wondering what the options are. I have a Black Bear tune, so it won't be difficult for Justin to modify my current tune if I upgrade.

 

[Erik the Awful]

How far do you want to go with your tune? You can go considerably larger on the cam with stock Vortec heads and injection with a few parts and a good enough tune. With a beehive valvespring parts combo you can go up to .530" lift. Then call your cam company of choice and tell them what you're looking for.

 

[kylenautique]

How far do you want to go with your tune? You can go considerably larger on the cam with stock Vortec heads and injection with a few parts and a good enough tune. With a beehive valvespring parts combo you can go up to .530" lift. Then call your cam company of choice and tell them what you're looking for.

Cool thanks for the info! I didn't realize I could get more lift out of my heads by changing out the springs. I thought it required more surgery than that.. I'm going to give comp cams a call. I found this article, and it looks like they got good results from the Comp Cam Xtreme Energy 08-500-8 cam, so that might be a good starting point. Has anyone used it?

Xtreme Energy Computer Controlled 206/212 Hydraulic Roller Cam for OE Roller SBC

Xtreme Energy Computer Controlled 206/212 Hydraulic Roller Cam for OE Roller SBC. For Stock throttle body 305 or 350. Very good economy and power.

www.compcams.com

Increased Power for Your 1996 to 2000 350ci Chevy Vortec 5700 V-8 Engine

Don't throw out that 5.7L Vortec engine! We show you why an engine swap may not be the best way forward.

www.motortrend.com

 

[kylenautique]

Comp Cams confirmed the 08-500-8 is the best cam for towing and hauling over the stock cam. I will need to swap out the valve springs to increase the lift. So, that's what I plan on going with unless someone recommends a better cam?

 

[L31MaxExpress]

I find it interesting that throughout the whole article they kept stating Crane Cams was the manufacturer for the various valve train parts when it was in fact Comp Cams. I ran the very similar Comp 4x4 206/210 @ 0.050 grind for a while. It had stump pulling low-speed torque. The 4x4 cam has more off-idle torque and snappier throttle response than the one they recomeended to you. It closes the intake valve a little sooner and traps a bit more cylinder pressure as well as opens the exhaust valve a little later further helping low-speed torque.. My 350 had no issues moving the van around town and on the highway. It held overdrive and converter lockup noticeably better than stock on hills and 6,000-7,000 lbs of trailer was much less noticeable behind the van. I switched to a GM 6395 cam after I had a lifter let go and trashed the 4x4 cam. The Comp 4x4 cam had noticeably better power everywhere than the GM 196/206 marine cam.

COMP Cams 08-409-8 COMP Cams Xtreme 4x4 Camshafts | Summit Racing

Free Shipping - COMP Cams Xtreme 4x4 Camshafts with qualifying orders of $109. Shop Camshafts at Summit Racing.

www.summitracing.com

 

[kylenautique]

I find it interesting that throughout the whole article they kept stating Crane Cams was the manufacturer for the various valve train parts when it was in fact Comp Cams. I ran the very similar Comp 4x4 206/210 @ 0.050 grind for a while. It had stump pulling low-speed torque. The 4x4 cam has more off-idle torque and snappier throttle response than the one they recomeended to you. It closes the intake valve a little sooner and traps a bit more cylinder pressure as well as opens the exhaust valve a little later further helping low-speed torque.. My 350 had no issues moving the van around town and on the highway. It held overdrive and converter lockup noticeably better than stock on hills and 6,000-7,000 lbs of trailer was much less noticeable behind the van. I switched to a GM 6395 cam after I had a lifter let go and trashed the 4x4 cam. The Comp 4x4 cam had noticeably better power everywhere than the GM 196/206 marine cam.

COMP Cams 08-409-8 COMP Cams Xtreme 4x4 Camshafts | Summit Racing

Free Shipping - COMP Cams Xtreme 4x4 Camshafts with qualifying orders of $109. Shop Camshafts at Summit Racing.

www.summitracing.com

Cool thanks for the info! The article is from 2016, and it looks like Comp Cams bought out crane cams. The part number and specs they listed were identical. Idk... As for the heads, to make the 08-409-8 cam work, did you just have to swap out the valve springs to allow for more lift?

 

[L31MaxExpress]

Cool thanks for the info! The article is from 2016, and it looks like Comp Cams bought out crane cams. The part number and specs they listed were identical. Idk... As for the heads, to make the 08-409-8 cam work, did you just have to swap out the valve springs to allow for more lift?

I ran 100% stock GM heads with that cam and 1.6 rockers. That being said, looking back I believe that is what caused the lifter failure. The springs did not have enough spring pressure to control the lifter and keep it in full contact with the camshaft and thus maintain valvetrain control. Valves floated a bit, lofted the lifter off the cam lobe, where it crashed back into the cam, causing damage that eventually wiped out the roller lifter wheel and the cam lobe. I have since learned from that mistake and make sure that the springs have adequate valve spring pressure to have atleast as much seat and open pressure as the cam manufacturer has listed for their matching spring package.

 

[L31MaxExpress]

I actually broke out some engine modeling software a few minutes ago. I modeled a stock L31 then added the 08-500-8, the 08-409-8 cam as well as the Summit 8800. The Summit 8800 also carries nearly identical specs. The power curves of all 3 you could lay over the top of each other with the only difference being under 2,000 rpm and above 5,000 rpm. At 1,500 rpm the 08-409-8 cam is about 5 ft/lbs stronger than the 08-500-8. At 5,500 rpm the 08-500-8 makes about 5 more hp than the 08-409-8. Then comes along the 8800. When I plugged in the specs off the Summit cam card, the 8800 was down about 10 ft/lbs at 1,500 rpm but up 10 hp at 5,500. I then noticed that the 8800 shows to drop in on a 111 ICL with a 112 LSA. The Comp cams both have 4* advance. Like any engine builder in the same situation, I modeled the effect of using the inexpensive Cloyes single roller 3-way adjustable timing set advancing the cam 4*. The 8800 fell right between the 08-409-8 and the 08-500-8. It splits the difference down low as well as up top and fell right in the middle of the two Comp Cams on the extreme ends. From 2,000-5,000 rpm the computer model does not show more than 1-2 tq or hp difference anywhere between the 3 cams. Given the cost difference and Comp Cams lack of availability, I would go with the Summit 8800 and Cloyes 9-1157.

 

[GoToGuy]

Did you consider a 383 ?

 

[kylenautique]

Did you consider a 383 ?

I did. The hard thing with the 383 is the cost. Its hard to spend $4500 on an engine when these trucks are only worth $6000. My 350 is tired, so I'm doing a rebuild, but I have a long block with 100,000 miles on it sitting in my garage, and it won't need any cylinder boring. Just cleaning, cam bearings, soft plugs, cylinder hone and the crank polished. Throwing some new rings and bearings in it, and a better cam. I may keep this truck for a long long time, so I can always build a 383 stroker later. I may upgrade to a diesel... Don't know yet.