Technical Vortec Heads on Gen1 350

I'm curious how much HP adding these heads onto a SBC 350 adds and if it is worthwhile to consider this add down the road. I'm also curious how I'd know if the engine should handle the add.

My current engine is a '74 SBC 350 bored 60 over, has an Isky 270/280 Mega Hydraulic Flat Tappet Cam. The pistons are Flat top (I believe Weisco) and are cast I believe (as they had casting marks) but it's been too many years since the motor was actually assembled. Never ran, but I did go back through her prior to dropping in current vehicle. I don't recall replacing the crank, so it might be original, but again been too long to recall. The current intake is a performer with Eddy 4 barrel. Machinist estimated it to be about a 330HP motor.

There is nothing currently wrong with motor and I'm currently happy with the setup, BUT....I have a '99 K1500 Burb with a 5.7L Vortec. The engine has 270k miles and runs decent, but has some sort of stutter I can't find. My plan at this stage is to drive her until she just dies, at which point, I might rob the rear diff for my '60 Burb and I'm wondering if it would be worth it to swap heads and maybe even swap over the intake as well. Is that a good or bad idea or would it be money ahead just to rebuild the Vortec motor if I want more power at that time? The current SBC only has 500miles on it, so still very fresh.

Like I said, just curious what others have found.....

 

Vortexes are limited in terms of cam lift, and you'll need to modify your intake manifold bolt holes or get a new one made for vortecs. If your cam will work, you should see more power. But if not, a new cam, etc and possible intake might cost more than any hp would be worth.

 

If you swap you need to run a coolant bypass hose or drill a hole in the passenger head to match coolant hole in the early block

 

That's the info I'm looking for. Thanks. How much more HP do they produce?

 

I am not sure it would make more H/P but the torque may go up some.
You will have to get an intake to fit those heads.

 

I've never head about drilling the head for a coolant thing. They are great heads out of the box. They have a limit of about "500 lift I believe from factory, but with beehive springs and or cut down spring pads they can be made to run a higher lift cam. HERE is the main thing with the vortec head for swap to consider... The intake manifold from your gen 1 will not fit without a bunch of modifying..( bolt angle is wrong plus the ports are much bigger on vortec heads so you would need to weld up the top of manifold). There are lots of aftermarket intake manifolds to bolt a carb (or carbs) onto the vortec heads. I'm gonna take a wild guess that compared to a mid 70's smog head the horsepower gain should be in the neighborhood of 50-75 but could be more with the other stuff thats already been done to the engine. Be careful though that your cmpression ratio isn't too high for your comfort with the flat tops. Vortecs from factory are around 62-64cc. Also I might know whats wrong with your burb...message me.

 

Got any pics of where to drill this hole ???

 

On the passenger or right side deck of the block you will see a hole about 1 1/2 inch below the top front head bolt on the pre 1996 block that is not there on the vortech . Use a head gasket to mark the location. This only needs to be done to the front of the right head.

 

I remember when the Vortech head first came out a lot of magazines tested them on the dyno and most got 30 or so more horses, without any other changes.

 

Different angles on intake manifold bolts on Vortec heads; vertical -vs- angled, 4 bolts (5/16") -vs- 6 bolts (3/8") per side, no heat crossover and raised intake ports. Here's an article on modifying the heads and another. A few more tricks here.
Check you piston to valve clearance when doing things.
http://www.hotrod.com/articles/small-block-intake-swaps-brake-drum-knock-out/

 

Like it's been said already, without machining their max lift is probably around .420-.450 and you'll need a different intake manifold. They don't like a lot of valve spring pressure with the press in rocker studs. If you've got smog-era garbage heads they're a great improvement. The Motor Trend show "Engine Masters" just did an episode where they put a cam and Vortec heads on a smogger 235 HP 350 and gained 129 horsepower.

 

TRUE Vortec heads (with the heart shaped combustion chambers) take a dedicated intake manifold, or your machinist can drill/tap the Vortec heads for an older style intake ($$$). Some aftermarket "Vortecs" are drilled/tapped for BOTH styles of intakes (older and dedicated Vortec-not swirl port). Post 1987, swirl port type heads have different angles for the two centermost intake manifold bolt holes; most guys just elongate the holes of the manifold and live with the mismatch, use angled spacers, or buy the right manifold. You are limited to 0.525 lift at the valve before you have to machine the guides, or use one of the aftermarket spring/retainer kits. IF your engine is running fine now, don't mess with it just to update to Vortecs. Vortecs are somewhat crack prone. And Vortecs are't traditional! I am Butch/56sedandelivery.

 

My cam is .465/.485 valve lift. My heads are nothing special, no clue if smog era or not. I have the numbers from them somewhere.

 

You're better off buying a set of aftermarket entry level aluminum heads. You'll be able to reuse your current intake without issue. Vortec heads also require aftermarket self aligning roller rockers that add additional expense to safely accommodate for more than .425 lift. Good looking centerbolt valve covers or adapters to use your old valve covers are expensive too. Speedway, jegs, and summit all offer heads that outflow them for less than $1000 fully assembled. You'll have more than that in rebuilding the heads and buying the other parts youll need.

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Bump. Is there an aftermarket head with votec style chambers that fits the early intakes, rockers, valve covers etc., basically bolt on?

 

Just about every current aluminum SBC head uses a fast burn style chamber.....so it comes down to how much do you want to spend and choosing a intake port runner volume that matches your power goals or existing engine parts list. Some early intakes don't have a tall enough port flange though, depending on what head you are fitting, some intakes won't seal well along the top of the intake ports. Valvecovers and rockers no problem.

Nobody makes an aftermarket head with a chamber exactly like the Vortec head, as the Vortec head isn't really that great a shape.....the aftermarket has cleaned up the shape a bunch compared to the rather untidy factory production shape.

 

Just as a bit of caution, 5 out of the last 6 that I checked were cracked.
Pete

 

The 99 350 will be a roller block also, why not just rebuild and add a few performance parts to it? That'll get you farther than an older 350. But again, be sure to have the heads checked for cracks being they're a light weight casting.
I am Butch/56sedandelivery.

 

Also exhaust manifolds. Center dump and rams horns do not work with the Vortec heads. The center 2 spark plugs are moved closer together. The factory manifolds are rear dump only. Having this prob with a friends 69 vet. He wants a crate motor. No good GM crate motors work with rams horns. Just the GM goodwrench 190 hp.

 

"Also exhaust manifolds. Center dump and rams horns do not work with the Vortec heads. The center 2 spark plugs are moved closer together. The factory manifolds are rear dump only. Having this prob with a friends 69 vet. He wants a crate motor. No good GM crate motors work with rams horns. Just the GM goodwrench 190 hp."
Thanks for this, I've been fighting plug wires for awhile now on my 330 hp crate motor with 2.5" rams horns. Looks like headers are in my future, any suggestions on those?

 

Here’s a “vortec” head (96-2000)
There are Only two casting numbers 062 and 906. Any other casting numbers are not a “vortec” head.
This head has been redrilled for earlier intake manifold to bolt up. You can see it doesn’t fit the intake port. The raised intake ports of the vortec heads is one of the things that makes them better. Welding up the manifold is useless, it makes a seal but castrated the port . Cutting back the intake and reconfigured reshaped re fabricated intake runner is what’s needed. It can be done but it’s stupid when aftermarket intakes that fit are available.


87-95 heads do not have the raised ports. 86 and earlier intake manifolds fit on 87-95 heads with some very easy modifications and wedge washers.

 

Thanks! So I have been perusing the aftermarket heads, and there are a lot of them! Foremost is my dished piston 305, which will need chambers under 60cc to keep compression (stock heads 58cc). That I think narrows it down to the Dart Iron Eagle 49cc heads. However the smallest intake is 200cc, and I'm not after top end. Or is it better (for low end grunt) to find a smaller runner and 64cc chamber?

 

Choose a head with a smaller runner volume and have it milled to reduce chamber volume is what is most commonly done.
A 2.02" intake valve head is going to be limited on how much lift you can have because the valve will hit the cylinder bore wall after something like .440" lift IIRC, on a 305 SBC. You'll want to research that issue if you are planning to try to put 2.02" valve heads on a 305....big valve is not really going to help you anyway, even if it clears the flow is going to be choked off badly by that small bore wall being too close to the valve. Investigate bore notching "eyebrows" for valve clearance and improved flow.
Being a 305 is going to eliminate a lot of your head choices. 1.94 is generally considered to be the max valve size on a 305.
Trick Flow has a head specifically made for 305 applications: Super 23° 175cc, 1.94"/1.5" valve 56cc chamber.
Trying to build a high power naturally aspirated 305 is a complete waste of time and money....stock engine with a small cam and a cheap small turbo kit will blow it away.
If you can manage to get 300 Hp out of a pump gas naturally aspirated 305 you are doing amazingly well. Harder to do than a 500HP 350.

 

If you really want only torque, then why are you looking at Vortech heads which increase HP ? Keep with the small chamber heads for more air velocity, use your existing (smaller) intake, and install a torque cam. Or spend up and get a crate 350, install vortech heads and a suitable Airgap manifold. Then you'll gain tq and hp. Most aftermarket Vortech heads will also require longer pushrods, a head stud kit, etc... so the cost will be double what you might expect.

 

Thanks, you sure know this stuff. I need to find those Trick Flow heads...

I have a small blower on it now. It goes like stink under boost but it's a dog otherwise and bad mileage. My lower end is sound but my stock heads have knurled guides that are toast and a single angle valve job (that's how I got it). So I figured a head upgrade is better than going through the stock ones. And the 'heart shaped' Vortec style chambers are supposed to boost torque and mileage. This is on my DD, I have two gas guzzling hot rods already..

 

Wiseco never made a cast piston. After that statement I was concerned you didn't really know what was really inside your engine. You better be sure what's in there before you go swapping heads, might end up with something that doesn't work at all. If you can't remember what piston it is, how do you know dome configuration, deck height and valve notches you have?
SPark

 

I don't know of any. I have not found any production center dump headers or manifolds for vortec heads. I think it custom only. Please post if you find any.

 

Headers typically are not a problem, don't need to be Vortec specific as the tubes are generally away from the plug area and out away from the head itself due to radius of bend(even on shorty/block hugger designs) by the time you get down to plug level. The problem with Rams horns is the collector area is so close to the head, directly below the two center exhaust ports and that is what interferes with the Vortec spark plug placement. It is the sides of the collector outlet area that interfere with the closer together spark plug placement. Vortec head they moved the spark plug in the combustion chamber closer to the exhaust valve, so that puts those two center spark plugs closer together outside the head and right where the Ramshorn outlet needs the space.

 

Blowby, I can certainly understand your desire to not waste money rebuilding junk stock heads, it is a dumb move in almost all cases in today's scene.
The fact it is a 305 is just killing your number of choices.

 

Why not take the money that would be spent on heads, etc and buy a crate 350 (P/N 10067353)?


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