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Topic: Vortec Head Questions

in Forum: C3 Engines

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Vortec Head Questions (1/9)
4/18/11 10:18pm

daveo76
Former Member
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 857

So I'm thinking of going with vortecs for my engine rebuild. Rebuild will be fairly mild - .030 over stock crank and rods, etc. I have a few questions about the heads, though, for those guys who have done this to their rides.

Intake: what intake did you use? Looks like two popular choices are the Edelbrock Performer and the GMPP option which I think is cast iron. Any thoughts? Will I have problems with clearance if I use a Q-Jet and stock air cleaner ass'y (going to go with one of those covers for it that have a K&N element built in)?

Exhaust: Will my original rams horn manifolds bolt up? I've seen conflicting posts on other sites with some stating that there is a problem with the back bolt on the passenger side. I know, I'll probably get some responses saying to just go with headers, but I don't want the expense and installation/maintenance hassles. Plus I want to keep the stock look and I'd have to get my pipes reconfigured.

Valve covers: has anyone used an adapter to allow use of old-style perimeter bolt covers? This is for that stock look thing, but I'd live without 'em. I might even look for some used L-98 style covers with the center bolts.

Finally - are there any must-do mods before bolting on a set of vortecs? Drilling and tap for screw-in studs? Minor porting in certain areas? Right now my plan is to buy a salvage yard set and have 'em rebuilt to pretty much OEM specs. But I'm flexible.... Also thinking about roller tip rockers....

Thanks - as usual sorry for the long post.

______________

1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

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Vortec Head Questions (2/9)
4/19/11 10:05am

Gunslinger
Former Member
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Frederick, MD - USA

Vette(s):
1969 convertible L71 427/435 4-speed black interior

Joined: 9/8/2003
Posts: 3398

I have a GM Performance 350HO in one of my cars...not a Vette though. It comes with Vortec heads. You definitely need a different intake. I installed Edelbrock EFI with their intake...basically a modified Torker intake. According to Edelbrock's catalog, the Performer Vortec will not fit under a stock Corvette hood. Whether that can be overcome with a drop base air cleaner I don't know.

Instead of Vortec heads, you might consider GM Performance Fast Burn heads...stock configuration and you can use a standard intake as well as your ram's horn exhaust manifolds. A friend has fast burn heads on his '66 Vette and says they made a world of difference...it was like an entirely new engine.

If you go with Vortecs like you're asking about, I have the adapters to use perimeter bolt valve covers. They work well...no issues, but make sure you follow the instructions are you can easily snap off on the the supplied bolts. Ask me how I know!

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Vortec Head Questions (3/9)
4/19/11 10:35pm

Gribble123

Lifetime Member
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Kingston, PA - USA

Vette(s):
1977 L-82 originally white/buckskin interior. Currently undergoing a frame-off resto. and modifications.YEEHAW!!!

Joined: 11/26/2003
Posts: 636

Slinger...I'll bite.

How do you know? LOL

Alan

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Vortec Head Questions (4/9)
4/19/11 10:57pm

Gunslinger
Former Member
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Frederick, MD - USA

Vette(s):
1969 convertible L71 427/435 4-speed black interior

Joined: 9/8/2003
Posts: 3398

[QUOTE=Gribble123]Slinger...I'll bite.

How do you know? LOL

Alan
[/QUOTE]

When I was installing the set I bought, rather use a torque wrench in inch/lbs as the instructions say, I simply tried tightening the bolts with a wrench. Sooo...I just had to give the threaded rod one more small twist to make sure it was tight...and SNAP! It broke off maybe 3/4 of the way down its length.

Luckily I was able to remove it without too much trouble. I had fears of needing to drill it out of the cylinder head and having to worry about all the metal shavings that might get loose in the oiling system causing damage.

I was making up profanity when that happened.

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Vortec Head Questions (5/9)
4/20/11 9:43pm

Sarge81

Lifetime Member
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WEST SENECA, NY - USA

Vette(s):
1981 Blue Ice Met. w/pearl ghost flames TKO500 5speed. LS1 Swap 3.45 Dana 44.

Joined: 12/3/2001
Posts: 2379

Same as Gunslinger. 350 HO w/Vortec heads. I put this engine in the vette quite a few years ago.

I used a Edelbrock Performer Vortec manifold with a dropped base air cleaner. It barely fit under the stock '81 hood. Now I have the L88 hood so clearance isn't an issue now. I had to upgrade the valve springs with the Comp Cam Beehive style springs and ARP screw in studs when I put the LT4 Hotcam in. The pressed in studs started to pull out with the higher lift cam.

Caution: DO NOT USE PROFORM SELF ALIGNING ROLLER ROCKERS! THEY ARE JUNK AND I HAVE PROOF! These things almost destroyed my engine. I'm trying out a set of Harland Sharp self aligning 1.6 roller rockers.

I put the valve cover adapters on with no problems. I like the look of the factory valve covers too.

Since I'm putting '69 style sidepipes on I bought a set off "knock off" 2.5" Ramhorn manifolds that I smoothed out. They bolted up just fine.

______________

GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.

3.54 Dana 44

'69 "N11" Sidepipes
Borgeson Steering Box
Born 8/1981
Sequence #3975

Click here to see more pics of my Vette on CarDomain.

Lifetime Member #26

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Vortec Head Questions (6/9)
4/21/11 1:19am

Thanks guys? Good info! Yep, I've seen the warnings about the Performers not fitting with stock air cleaners. But this one seems like it might fit:

http://www.race-mart.com/GM_Performance_Parts-GMP-10185063.html

I think installing screw-in studs would be a good idea as well. Sounds like the stock heads may also need to be modded to allow higher lift -- max of .474 or something like that? Need to do a bit more research before I go this route. Sarge, saw the pics on your website (I'm jealous), but do you have any after you installed the manifolds?

______________

1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

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Vortec Head Questions (7/9)
4/21/11 2:10pm

Sarge81

Lifetime Member
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WEST SENECA, NY - USA

Vette(s):
1981 Blue Ice Met. w/pearl ghost flames TKO500 5speed. LS1 Swap 3.45 Dana 44.

Joined: 12/3/2001
Posts: 2379

[QUOTE=daveo76]

[/QUOTE]

Thanks for the compliment. I will post more pics on that link over the weekend. Manifold pics that is.

The OEM Ramhorns with the little squarish/rectangular bumps on top of each manifold will probably need to be smoothed or shaved off due to the fact that the valve cover gasket rail on the cylinder head cants outward slightly not allowing the manifold to be mounted up tight to the exhaust port openings.

I ran into this problem years ago with ramhorns and vortec heads.

______________

GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.

3.54 Dana 44

'69 "N11" Sidepipes
Borgeson Steering Box
Born 8/1981
Sequence #3975

Click here to see more pics of my Vette on CarDomain.

Lifetime Member #26

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Vortec Head Questions (8/9)
4/21/11 11:59pm

Yep, I just went out and looked at my manifolds and they definitely have those bumps. Seems like they could be shaved off without too much worry or hassle.

I also just realized I posted the wrong link for the intake -- ZZ manifold for old-style heads. Here's the correct one: http://www.jegs.com/i/GM+Performance/809/12496820/10002/-1

______________

1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

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Vortec Head Questions (9/9)
4/23/11 10:01pm

Sarge81

Lifetime Member
Send Private Message

WEST SENECA, NY - USA

Vette(s):
1981 Blue Ice Met. w/pearl ghost flames TKO500 5speed. LS1 Swap 3.45 Dana 44.

Joined: 12/3/2001
Posts: 2379

Dave, I put a couple new pics on my link for Car Domain. You can see how close the manifold sits near the cylinder head. And a couple other shots.

______________

GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.

3.54 Dana 44

'69 "N11" Sidepipes
Borgeson Steering Box
Born 8/1981
Sequence #3975

Click here to see more pics of my Vette on CarDomain.

Lifetime Member #26

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