Cam Setup For L31 350 Vortec

[Schurkey]

I like the new list more than the original.

Probably want to verify piston-to-valve clearance, retainer to guide clearance, and valve spring installed height.

 

[Erik the Awful]

What are you doing with the heads? At least give them a cleanup port job. The cam has a lot of potential, but your constraint will be the heads.

 

[rebelyell]

Im not sure if this thread is dead but after looking at all the recommendations my updated list of parts is.

Cam: https://www.summitracing.com/parts/sum-8802
Valve Springs:https://www.summitracing.com/parts/cca-26918vcs-kit?rrec=true (Includes new valve seals and retainers and Caps)
Rocker Arms: https://www.summitracing.com/parts/cca-1617-16
Timing Chain: https://www.summitracing.com/parts/clo-9-1157 (Replacing for extra timing control and to just replace to that way i know its 100% AOK)
Pushrods: Use Length Checker and order once the valve-train/cam is in

Again, sir: here is an example where ya must Look before ya leap. Told ya about the retainers. I know the summit site tells you they're for vortec L31 But also states for 0.313" stems (that's about 8mm) ...iron L31 Vortec heads do Not come with metric valve stems or metric retainers aka caps or metric locks aka keepers. They are 11/32" aka about 0.343" considerably larger than 8mm (LS size). Trust/Believe summit or comp or even me ... But VERIFY any & all ... that's part of doing it right. Without verification, you're at risk of pizzing away lotsa time, money and stress.
I make this dire prediction: if you try and mix the wrong size retainers/locks/stems ... and ya get it to run ... it WILL drop a valve or three.

? ya gonna measure your vortec's valve stems ??
? ya gonna install guide plates with those overkill roller rockers??
? Ya gonna first R&R correct rocker studs as well??
? do ya think the phone bank at summit is staffed by experienced engine builders ??

Good luck with your project; trust but verify

 

[TStowell]

Again, sir: here is an example where ya must Look before ya leap. Told ya about the retainers. I know the summit site tells you they're for vortec L31 But also states for 0.313" stems (that's about 8mm) ...iron L31 Vortec heads do Not come with metric valve stems or metric retainers aka caps or metric locks aka keepers. They are 11/32" aka about 0.343" considerably larger than 8mm (LS size). Trust/Believe summit or comp or even me ... But VERIFY any & all ... that's part of doing it right. Without verification, you're at risk of pizzing away lotsa time, money and stress.
I make this dire prediction: if you try and mix the wrong size retainers/locks/stems ... and ya get it to run ... it WILL drop a valve or three.

? ya gonna measure your vortec's valve stems ??
? ya gonna install guide plates with those overkill roller rockers??
? Ya gonna first R&R correct rocker studs as well??
? do ya think the phone bank at summit is staffed by experienced engine builders ??

Good luck with your project; trust but verify

Hi i was looking at those valve springs and i forgot that you said that this may be dumb question but should i buy everything separately like springs, retainers, locks, seals, ect or should I buy that kit and get new locks and retainers at the correct 11/32" size. Do you think guide plates are really worth it because im absolutely willing to spend the money to get them if it is. Also should i replace the rocker studs the motor is a remanufactured motor with new heads it only has about 9,000 miles on it ?

 

[rebelyell]

Oh, it's a reman L31 ...who KNOWS what's in it? ... all the more reason to FIRST measure valve stem OD. Guide plates are not a matter of whether they're worth it or not. OE stamped shoe type rockers are Very forgiving as far as alignment is concerned --- NOT so with any roller TIP ... Roller Tips Must be properly aligned with valve tip ...otherwise the rocker typically runs off side of valve, knocking locks loose and dropping a valve. Guide plates are used to align roller to tip. OR a self-align roller tip aka rail type can also align roller tip to valve tip. But Never use plates WITH rail --- only one or the other.
Unless you have unlimited budget, I advise using a hi-grade shoe type rocker with long slot. Elgin black ice (cryo treated). Shoe type are also Very forgiving in regard to pushrod length.

OE vortec rocker studs are pressed into heads (not threaded as Hi-Po are) AND they're Not proper shape for use with Roller trunnion aka fulcrum rockers. Vortec heads must be drilled & tapped for threaded studs.

Once ya KNOW what you've got, Alex's Parts offers 2 or 3 "drop-in" spring-retainer-lock kits to fit GM vortec heads... each kit under $200.

Don't think I said anything about dumb questions ... there are none ... what's dumb is when ya don't ask questions OR if ya fail to inform the leader everything that ya know or when something's wrong.

Me thinks you may benefit a lot from reading a couple basic performance sbc build manuals. I can't / won't try to teach it in a thread. Vizard wrote at least one Hi-Po sbc build book & maybe you might get that one under your belt before ya proceed.

GM sells brand new (Not reman) L31 replacement motors for under $4700 delivered : steel crank, completed fuel pump mount, hands down best warranty in the industry ... such as
https://www.gmperformancemotor.com/parts/19432779.html

 

[TStowell]

Oh, it's a reman L31 ...who KNOWS what's in it? ... all the more reason to FIRST measure valve stem OD. Guide plates are not a matter of whether they're worth it or not. OE stamped shoe type rockers are Very forgiving as far as alignment is concerned --- NOT so with any roller TIP ... Roller Tips Must be properly aligned with valve tip ...otherwise the rocker typically runs off side of valve, knocking locks loose and dropping a valve. Guide plates are used to align roller to tip. OR a self-align roller tip aka rail type can also align roller tip to valve tip. But Never use plates WITH rail --- only one or the other.
Unless you have unlimited budget, I advise using a hi-grade shoe type rocker with long slot. Elgin black ice (cryo treated). Shoe type are also Very forgiving in regard to pushrod length.

OE vortec rocker studs are pressed into heads (not threaded as Hi-Po are) AND they're Not proper shape for use with Roller trunnion aka fulcrum rockers. Vortec heads must be drilled & tapped for threaded studs.

Once ya KNOW what you've got, Alex's Parts offers 2 or 3 "drop-in" spring-retainer-lock kits to fit GM vortec heads... each kit under $200.

Don't think I said anything about dumb questions ... there are none ... what's dumb is when ya don't ask questions OR if ya fail to inform the leader everything that ya know or when something's wrong.

Me thinks you may benefit a lot from reading a couple basic performance sbc build manuals. I can't / won't try to teach it in a thread. Vizard wrote at least one Hi-Po sbc build book & maybe you might get that one under your belt before ya proceed.

GM sells brand new (Not reman) L31 replacement motors for under $4700 delivered : steel crank, completed fuel pump mount, hands down best warranty in the industry ... such as
https://www.gmperformancemotor.com/parts/19432779.html

ILe look into those valve kits from Alex parts, the guide plates and the studs and Ile start finding some build manuals. I'm newer to Cam and valve trains so I'm just trying to research everything before I spend any money so I appreciate it.

 

[Frank Enstein]

After you have chosen your cam get the recommended springs, retainers, and locks for that cam.
The recommended parts have been tested and proven to work together.
Get a quote for machining the heads vs. purchasing new heads. You might be surprised at the difference.
My rule of thumb for rockers is; Under .480 lift stock rockers. Between .480 and .500 roller tip rockers (self aligning for Vortec heads) and above .500 lift full rollers.
Pushrod length MUST be checked. Get the length wrong and you'll beat the guides out of the heads in short order.

 

[rebelyell]

When considering what type of rocker arms to use (or to avoid); note the following:
Vast majority of rocker arm friction (& heat generation) is in the Fulcrum aka pivot aka trunnion; Not at/in tip.
When GM designed the modern LS series; its RAs have bearings/rollers in its trunnion, but Not at or in tip.

the above has been professionally verified ad nauseam via Spintron analyses.

 

[L31MaxExpress]

When considering what type of rocker arms to use (or to avoid); note the following:
Vast majority of rocker arm friction (& heat generation) is in the Fulcrum aka pivot aka trunnion; Not at/in tip.
When GM designed the modern LS series; its RAs have bearings/rollers in its trunnion, but Not at or in tip.

the above has been professionally verified ad nauseam via Spintron analyses.

I am a full roller person. Works even with a stock cam. The full rollers are more durable as well, especially with lower levels of ZDDP in the oil.

 

[rebelyell]

I am a full roller person. Works even with a stock cam. The full rollers are more durable as well, especially with lower levels of ZDDP in the oil.

I'm favorably impressed by much of what you've accomplished and appreciate much of the knowledge you've shared; but here, I Disagree in both application and principle. Again, and like a dyno, Spintron don't lie. Also, (understatement) I have more respect for GM Vortec heads than you seem to. Opinions.

I'm selective; not one size fits all. Overall, stamped RAs (including OE) work rather well and live long, even in extraordinarily harsh conditions; reference GM's L31-based "602" CT350 campaign.
FWIW, stamped RAs are good candidates for cryo as well as for lapping-in their pivot-balls.

Cheap "roller tip" RAs are known to fail at tip with short MTBF; when that roller tip affects friction reduction little-to-none. Accident looking for a home; Not always so durable. Every motor/build don't rate top-quality full-roller RAs; and cheap full-roller RAs carry too great a risk for failure. Your $ your motor.

Notwithstanding my above positions, I do also run quality full-rollers; when and where they're practical.
I wish crane RAs were still available new; I still have sets of gold race. I wish they'd continued to develop their hybrid which was essentially a gold race But, instead of a roller-tip, was shod with a precision tool steel slider "shoe."