Vortec head rebuild

[Don Loeser]

So I'm building a 383 out of a gen 1 roller block. I have these vortec heads off of a 99 suburban I'm going to rebuild. Beehive springs with comp cam retainers and new locks. Also comp cam 1.6 roller rockers. Hoping to get some opinions on cams from people who have done this. What kind of lift are people running after this mod. Thanks

 

[Schurkey]

Given the basic limitations of the Vortec heads, you'd need to verify retainer-to-seal clearance, and the max lift on the valve springs.

If the heads aren't ported, I'm thinking something like .525 lift is about all you'd need. Porting Vortec heads is tricky, it's easy to screw-up low-lift flow trying to gain peak flow.

 

[Supercharged111]

So I'm building a 383 out of a gen 1 roller block. I have these vortec heads off of a 99 suburban I'm going to rebuild. Beehive springs with comp cam retainers and new locks. Also comp cam 1.6 roller rockers. Hoping to get some opinions on cams from people who have done this. What kind of lift are people running after this mod. Thanks

Watch the installed height on those springs. The Vortec heads are .100" off of a typical LS beehive.

 

[Don Loeser]

I got the comp Cams beehive springs. It says ls springs are good to .625 I believe. I just got a stage 2 cam with .525 lift. With the 1.6 roller rockers I'm hopeful. I'll check valve clearance but was hoping to get some first hand reassurance.

 

[Supercharged111]

I got the comp Cams beehive springs. It says ls springs are good to .625 I believe. I just got a stage 2 cam with .525 lift. With the 1.6 roller rockers I'm hopeful. I'll check valve clearance but was hoping to get some first hand reassurance.

Good to .625" lift when installed at their specified height, yes. When not, that affects max lift, seat, and nose pressures.

 

[Insert Quarter]

I believe the valve guide itself is the limiting factor on lift for vortec heads. Just make sure to only cut down what you need and not run the cutter all the way down to the spring seat. You want to leave as much guide as you can to support the valve stem, plus it'll need different size seals to match the cutter.

http://www.superchevy.com/how-to/148-0208-vortec-heads-valve-lift/

 

[Hipster]

Lifting the valve to .560 with 1.6's is past where the port stalls on stock vortecs. Intake velocity drops, cylinder filling drops, less power and depending on how bad can make it difficult to tune.

Last set of iron heads I had done. Tanked, magnafluxed, surfaced, 8 new exhaust guide liners, cut guides, 3 angle seats , back face exhaust valves, measure/assemble/shim springs etc was north of $600 with me supplying the springs/locks retainers, and new valves. It was not an option for that engine but I was pretty close to aftermarket aluminum head territory $$ wise with much lesser head.

 

[L31MaxExpress]

Lifting the valve to .560 with 1.6's is past where the port stalls on stock vortecs. Intake velocity drops, cylinder filling drops, less power and depending on how bad can make it difficult to tune.

Last set of iron heads I had done. Tanked, magnafluxed, surfaced, 8 new exhaust guide liners, cut guides, 3 angle seats , back face exhaust valves, measure/assemble/shim springs etc was north of $600 with me supplying the springs/locks retainers, and new valves. It was not an option for that engine but I was pretty close to aftermarket aluminum head territory $$ wise with much lesser head.

I had a set of 062 castings peak at 218cfm @ 0.400 then fall of to 210 @ 0.450. Add in the cracking issue, the spring/retainer change, the lack of pushrod guideplates and the weak single spring, better to just get an aluminum head.

I had 210cc aluminum heads on my 383.

 

[Hipster]

I had a set of 062 castings peak at 218cfm @ 0.400 then fall of to 210 @ 0.450. Add in the cracking issue, the spring/retainer change, the lack of pushrod guideplates and the weak single spring, better to just get an aluminum head.

I had 210cc aluminum heads on my 383.

I didn't think they stalled that low. Thought it was around .510-.520. Way back I messed with a few sets of AFR 195's they stalled right around .550 and even those were were considered too small for a well built 383 at the time and never considered a "race" head.

I tend to error on the conservative side for street engines and would be inclined to forego the 1.6's. A 3 angle and blending the vj to the bowl would be a good idea.

 

[PlayingWithTBI]

Here's a chart, I found a while back, that may help.

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