85z28iroc

I have a 85 IROC with a burnt 305. Bought a 350 out of an 81 3/4 ton camper special. I want to know if Vortec Heads will fit? Do they have to be heads from a 5.7L, or will heads from a 4.8 or 5.3L also fit? I know I will have to purchase a new intake manifoild, probably an Edelbrock Performer EPS, but will all the other components still bolt on? ie. alternator, A/C compressor, etc. Also, would a 350 HP 327 cam be a good match for this engine? I want the car to be fast, but still highway driveable. What kind of horsepower would this combination put out?

xpndbl3

they must be either 906 or 062 heads only. you then need the vortec intake, i'd recommend the performer-rpm air gap. the old 350hp 327 cam is just that old technology. i would recommend the XE268 or XE274 by comp instead. with the XE274 and vortec heads you should make 400hp, but the guides will need to be cut down and spring pockets machined for bigger springs and screw in studs installed would be recommend. i got all that done for $200 in machine work.

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85z28iroc

Do those 2 numbers of Vortec Heads come on 4.8, 5.3 and 5.7L engines?
Are they found in only certain year vehicles?
Do those heads have all the mounting holes for the alt., A/C comp., etc.?
400 HP is more than I am looking for. 275 - 300 HP is all I want. I have a 1406 Edelbrock 600cfm Carb. Fuel mileage / driveability is also an issue.
Please suggest cam and intake for this HP range.

five7kid

5.7 only.

'96-'99.

All accessory holes are there.

XE262 for good idle, good power, good economy. Much, much better than an old low-lift, high overlap factory grind.

85z28iroc

Who makes the XE262 cam?
Will the stock springs on those Vortec heads be sufficient for this cam?
What intake manifold would you suggest for this combination?
What kind of HP might this engine produce?

Fast355

1996-2002! The L31 heads are virtually identical to the L30 heads used on the 305 vortec.

five7kid

Competition Cams.

Perhaps, but probably not.

Performer or Performer RPM.

Should be well over 300 gross flywheel.

bretsk2500

nothing on a 4.8 or a 5.3 (GenIII) will work on a gen 1 SBC motor. Gen III 5.7(LS1)'s are NOT the same as a Gen 1 SBC 5.7 (350).

Abird4u2nv1

the L30 heads you referred to are close to the l31. Smaller valves, smaller combustion chamber, Put bigger valves in em and enlarge the chamber and they will be good for a 350

85z28iroc

So, these L31 Vortec Heads will not work on my 1981 350?

bretsk2500

yes, the L31 heads will. an L31 is a regular old SBC with the LT1 port setup grafted onto it and a provision for a cam sensor added. it's considered a gen 1-E (for Enhanced). the heads bolt up just fine to a gen 1 SBC [i.e. not a Gen II (LT1,LT4) or a Gen 3 (4.8, 5.3, LS1/6 5.7, 6.0, 7.0)], but require a special intake for the extra tall intake ports.

Remember, After '96 ALL chevy motors were Vortecs, regardless of design. there are I5,I6,V6 and V8 vortecs.

five7kid

They're all called "Vortec", but that doesn't mean any Vortec V8 head will fit an '81 block.

bretsk2500

and *that* was exactly my point.

Chevyguy496

I am in the process of putting modified vortecs on my mud truck right now. I have 98 Vortec heads, 3 angle competition valve job, and Manley valves. The accesory holes are there. I'm using standard head gaskets, Arp head bolts and intake bolts. The cam should hopefully be here thursday. It is a mild crane grind. The only thing I'm not sure of is if I'll need longer/shorter pushrods, but I'll sort it out if it comes up. The intake isn't matched to what I'm using it for (I bought it to go in my Camaro, but I'm using a big block now) but its a vortec intake and I paid for it, so I'm using the damn thing (Vr.Jr)

On stock vortec heads you can get away with running no more than .460 lift on intake and exhaust. While that is a pretty small cam for a performance application but the heads outflow the old 2.02 heads and you get a bump in compression because vortecs have 64cc chambers as opposed to the typical 72cc on old style heads. If you use the vortecs buy a new cam, they are right,the 327 cam is old technology. Make sure you check for spring and guide clearance if you go aggressive though.

BTW, just because they have centerbolt valvecovers doesn't mean it is a vortec head, Vortec heads are 96 and newer only. Make sure you check the casting numbers. Vortecs also have a zig-zag pattern on the front.

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regal301

96-00 5.0 & 5.7 heads are what will fit. best head for short money. you will loose egr. but accesories will be unchanged.need 96 up intake gaskets and special intake.make sure to get the rocker arms with the heads!!!!!!

Air_Adam

Incorrect on two points:

- The L31 heads had LT1-derived combustion chambers, not ports. The LT1 heads had the standard Gen 1 port layout, just with a slightly altered intake bolt pattern. Thats why lots of TPI guys can convert an LT1 intake to use on their stock heads. Vortec heads have a totally unique intake port layout.

- The heads have nothing to do with the cam sensor. On a Vortec motor (L31) the cam sensor is part of the distributor and/or timing chain cover, not the cylinder heads.

camarochrisz28

I am looking to buy a set of vortec heads for my 91z28 350 tpi as well as the special intake,does anyone know where i can find these heads/intake online?

Thanks guys

Mikejr1986

Scoggin dickey chevy in lubbuck has designed a custom direct bolt on intake to vortec heads ideal for any 3rd gen tpi 350 cars... Must read if wanting vortec heads http://www.camaroperformers.com/cama...l/viewall.html