I’m a little confused about cylinder heads for a small block Chevy. I thought all the heads interchanged. My buddy tells me that certain late model heads don’t use the same intake manifold—but he couldn’t tell me specifics. I was thinking of using a set of later model heads from a mid 1990s 350 TBI truck on an engine I’m building.

I think he’s blowing smoke but I thought I’d better ask around. Any input on this?


While you might not want to hear this, your buddy is at least partly true—but he didn’t follow through with all the rest of the information.

Don’t worry, we can fill in the missing details. As it turns out, there are several different patterns and heads that you need to know about if you are going to start swapping cylinder heads from different engines.

We’ll warn you now—they do not freely interchange. 

The Original SBC Cylinder Heads

The original small block Chevy started life in 1955 and those original heads established a pattern for the intake manifold with six bots per side that were machined perpendicular to the intake port face. We won’t get into all the different valve and combustion chamber sizes as there are multiple variations. Each change in chamber volume will have an effect on compression, so it’s important to know the numbers.

Roughly in 1969, Chevy added accessory bolt holes to the ends of the cylinder heads. But at least all these early head will interchange. These heads were used for 1955 through the mid 1980s and beyond.

The TBI Truck SBC Cylinder Heads

SBC Chevy cylinder head on a table
The TBI truck heads used this oddball intake bolt pattern where the angle for the center two bolts is different than the bolt angle on the outboard bolt holes. This makes these heads only useful for the specific TBI manifold. Edelbrock, for one, makes a dual plane intake manifold for these heads should you want to do that, but the heads are not really worth investing much as their flow potential is limited. (Image/Jeff Smith)

The first major change to the heads occurred when Chevy introduced throttle body injection (TBI) in trucks for 1987. For some reason, these engines from 1987 through 1995 employed a different intake manifold bolt angle for the two center intake manifold bolts on each head.

This configuration is unique to only these cylinder heads.

The aftermarket now makes performance, dual plane intake manifolds for these engines should you desire to upgrade. As an example, Edelbrock makes a Performer dual plane intake (PN EDL-2104) for these engines. Frankly, the heads are not all that great in terms of intake or exhaust flow so they certainly should not be considered for any performance application.

These heads were also the first to employ the centerbolt valve cover configuration where four small bolts are in the center of the valve cover as opposed to earlier, traditional heads using the four perimeter bolts.

Vortec SBC Cylinder Heads

SBC Chevy cylinder head
Summit Racing sells a brand new, iron Vortec cylinder head completely assembled that replicates the original Vortec head with some minor improvements for a very affordable price. (Image/Jeff Smith)

To further complicate this issue, Chevrolet subsequently introduced the Vortec truck engines in 1996. The cylinder heads were an all new configuration where the intake manifold bolt pattern only employed four bolts total to attach the intake manifold to each head. These bolts were no longer perpendicular to the intake manifold face. Instead, these bolts are angled more vertically.

This cylinder head also used the centerbolt valve cover design, but based on the above description of the early TBI engines, not all centerbolt valve covers are Vortec truck heads.

The Vortec iron head is more highly prized because at the time of its introduction, it was the best flowing production cylinder head and even out-flowed the aftermarket Bow Tie head that Chevrolet offered at the time! These Vortec heads also featured a redesigned combustion chamber with a much smaller 64cc chamber volume and a new spark plug configuration as well.

Of all the later small block iron production castings, these Vortec heads are a much better choice for any mild small block engine build. The heads have become so in demand that several companies, including Summit Racing, now offer their own casting version of the original Vortec head (PN SUM-151124). Keep in mind that these heads use a 64cc chamber, which is great for use with engines with flat top pistons as this will drastically help compression on older engines with 76cc chambers and 8.5:1 compression.

A minor twist to this story is the mid-1980s through early 1990s Tuned Port Induction (TPI) engines. While this engine began its life in 1985 in Corvette and Camaros, these engines did not use the mid-1980s TBI bolt pattern. Instead, these heads used the traditional small block six-bolt-per-head intake manifold bolt pattern but did include the centerbolt valve cover configuration.

While some of these heads were aluminum—used in the Corvettes—they were not necessarily a good flowing head from a performance standpoint. The iron Vortec truck heads are far better flowing heads.

Why didn’t Chevy cast the Vortec heads in aluminum? That’s a really good question.

SBC Chevy cylinder head on a workbench
This is the aluminum TPI Corvette head from the late 1980s that uses the standard SBC intake manifold bolt pattern, but with the centerbolt valve cover arrangement. These heads don’t flow even as well as the truck Vortec heads. As a result, they have a limited following. (Image/Jeff Smith)

Gen. II LT1 SBC Cylinder Heads

Then to complicate things even further, the Generation II small block introduced in 1992, labeled the LT1, reversed the coolant path. Earlier engines pushed coolant through the block first and then into the heads. The LT1 pushed coolant through the head first then down into the block. For this reason, these Gen. II heads will not interchange with earlier engines, even though the head bolt pattern is still the same as the traditional engines.


So you can see that when it comes to small block Chevy heads, there have been quite a few changes over the years. But then, when the same basic engine has been in production for almost 70 years (if we count the LS Gen. III-IV and now Gen. V), it’s little wonder that there have not been many more.

YearSBC Cylinder Head Design
1955 – CurrentStandard Small Block Chevy Head
1987 – 95Center Two Intake Manifold Bolt Angle Change
1996 – 2000Vortec Head – Different Intake Manifold Bolt Pattern
1992 – 97Gen. II LT1
This short chart lists the four different basic configurations of small block Chevy cylinder heads.

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Author: Jeff Smith

Jeff Smith has had a passion for cars since he began working at his grandfather's gas station at the age 10. After graduating from Iowa State University with a journalism degree in 1978, he combined his two passions: cars and writing. Smith began writing for Car Craft magazine in 1979 and became editor in 1984. In 1987, he assumed the role of editor for Hot Rod magazine before returning to his first love of writing technical stories. Since 2003, Jeff has held various positions at Car Craft (including editor), has written books on small block Chevy performance, and even cultivated an impressive collection of 1965 and 1966 Chevelles. Now he serves as a regular contributor to OnAllCylinders.