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Vortec Heads - Big HP Jump!

14K views 9 replies 8 participants last post by  OldSkoolPala 
#1 ·
This forum has helped me so much, glad to give some advice (instead of just taking it!).

65 Impala Convertible, love this car. Original 283 gone before I purchased, replaced by '72 SBC 350, with stock 882 smogger heads, stock cam, 75 Qjet carb., 69 Corvette/Camaro intake (3927184), stock exhaust manifold. Ran smooth, but not much power, 0-60 in around 12-13 seconds with stock 2 speed Powerglide.

Bought JEGS headers, and a set of Vortec heads (062) from local junkyard, along with Edelbrock Vortec intake. Yard pressure tested and guaranteed heads. My mechanic cleaned up heads, and installed everything. Feels like an entirely different car! Great acceleration, much, much faster, new 0-60 is 8.5 seconds!

I had read a lot about these Vortec heads, and it was all true. Installing them along with headers, feels like I gained 100 horsepower, pretty cool.
 

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#5 ·
Can those Vortec heads go on a 327?
Yes they can. However they have their own little idocentricities:

First they are late model heads (computer designed to maximize swirl in the combustion chamber to reduce emissions). So you have to use late model drip proof center bolt valve covers.

To reduce the cost of a stamped piece of steel GM dropped guide plates bolted under the rocker arm studs (good news is the rocker arm studs bolt on instead of being pressed in like your old 327 heads have). Since rockers have to guided by something they dimpled the rocker arm to capture the valve stem tip and center off of that so it requires self guiding rockers (either factory stamped steel or roller rockers with guides).

The heads use a bee-hive valve spring instead of a fixed diameter spring to cut the cost of a separate harmonic damper (the flat steel ribbon you see inside traditional valve springs). This means it has a different keeper and valve spring and needs the heads to be machined if you want to use a traditional valve spring and oil slinger on the valve stem.

Also the heads have four fewer bolts bolting on the intake manifold (that saves four bolts per truck, and we make several million trucks a year. That savings pays for the executive board's meeting in Cancun Mexico; and that special room service we all love when the wives are back home) and they came with EFI instead of a carb so you need a special "Vortec" intake manifold.

Finally the heads are limited to a 0.480" inch maximum valve lift before the keeper hits the top of the head's valve guide. You can have the heads machined for press on valve guide oil seals and cut down the guide to offer a maximum of 0.520" inch valve lift when you cut larger spring pockets to run regular valve springs.

Or for about the same amount of money as paying for the machine work and the cost of used heads buy a set of aftermarket heads from World Products (their Sportsman II cast iron heads) that flow as well as the Vortec heads (Bill Mitchell copied all of the design features of the Vortec head that makes them work so well; except for the raised intake ports that require a different intake manifold), but kept all of the looks (valve covers, push rod guide plates, and reuses the stock SBC intakes) so it can pass for a stock Chevy head utilizing what you already have. Plus you can run up to 0.680" valve lift if you want with the Sportsman heads.

Big Dave
 
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