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Fitting PML Valve Covers on 1959 to 1986, Perimeter Mount, Small Block Chevy Engines

PML small block Chevy valve covers work with many roller rocker systems. Always check for clearance before ordering. Here are some issues and examples to keep in mind.

Note: we have heard of engine builders who grind off part of our valve covers to make additional clearance. Keep in mind we cannot warranty our products once modified or accept returns in any condition except new. Not that you'd ever want or need to return them. (See our Returns Policy.)

Internal Baffle and Roller Rocker Clearance

PML Small Block Chevy valve covers have an internal baffle that reduces oil blow-by when the covers are machined with PCV and breather holes. The baffle is about 1.2 inches wide. For many cylinder heads and roller rocker systems, there is plenty of clearance. For some, the space between the rocker pins is less than the width of the baffle.

If there is not enough space between the pins for the baffle, part of the baffle wall can be removed. PML can machine the baffle to reduce the size for $45.00 per cover. Call or email us if you need information or need to order this custom machining and let us know the space between your roller rockers.
valve cover internal baffle   valve cover baffle, machined  

Edelbrock Performer RPM Kit and PML Small Block Chevy Valve Covers

With some Edelbrock Performer RPM kits, the space between the pins is 1.16 inches. . However, the baffle on the PML valve covers will hit the pins unless the baffle is reduced in size. PML machined the baffle to reduce the size for this application:
Edelbrock Performer Heads   Edelbrock kit roller rocker pins   PML valve covers with Edelbrock Performer RPM kit

The cylinder head is number 6089. The PML valve cover shown is our 25th anniversary edition but the same information applies to all PML small block Chevy perimeter mount valve covers. Our thanks to Braun's Automotive in Lomita, CA for working with us. Contact Braun's at (310) 325-4303 or see

AFR Heads With Comp Cam Rockers and PML Small Block Chevy Valve Covers

Our thanks to Jerry with his AFR Model # 0916 180cc Street Rod Eliminator Cylinder Heads and Comp Cam Ultra Pro Magnum Roller Rockers. On this setup, there is about 1.22 inches between the roller rockers. Jerry selected Fel Pro Performance Gaskets 1604, which are double thick. He reported that PML valve covers fit easily although longer bolts might be needed. Jerry used a Dremel tool to remove some material from the baffle so that even without the gaskets the PML covers fit easily. This information for reference, not tested or endorsed by PML. Our thanks to Jerry for his information and pictures.

AFR Heads and Comp Cam Roller Rockers distance between pins   Comp Cam Roller Rockers on AFR heads   PML valve covers with Comp Cam Roller Rockers on AFR heads   PML valve covers baffle, modified
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T&D Rocker Arms and PML Small Block Chevy Valve Covers

PML valve covers are not compatible with T&D Shaft Mounted Rocker Arms.

The T&D Machine Products Competition Rocker Arms are shown in the image at left. The shaft mounts are very tall, almost to the top of the rocker arms. The PML cast-in internal baffles will contact these mounts.

shaft mounted rocker arms
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Scorpion Narrow Body Rocker Arms

One of our customers has used our valve covers on several of his small block engines recommends Scorpion Narrow Body Rocker Arms. He reported to us that our valve covers fit well and he has not had any clearance issues using these rockers. His most recent build includes 180 Dart heads, a thick Fel-Pro gasket, Scorpion Narrow Body rockers, and, of course, PML valve covers.

We at PML have not tested this configuraton. This information is for reference only.

Height of Roller Rockers

Internally, PML valve covers are a little taller than stock covers. See these PDF files for dimensions:

  • For Part Numbers 8357-2, 8357-6, 8357-7: click here for dimensions in a pdf file. A separate window will open and load the file.
  • For Part Numbers 10430, 11026, 11106,11107: here for dimensions in a pdf file. A separate window will open and load the file.

There is no correlation between roller rocker ratio and fitment of our valve covers. You will need to check actual physical size of the parts.

Engine configurations vary greatly, and PML does not recommend or endorse the use of any particular roller rocker system or engine configuration.

Thick Gaskets

This information is for reference. PML has not tried these gaskets and does not have an opinion on how they fit or function.

Some customers reported that they needed a little more height to add clearance between the gasket surface and the inside top of PML valve covers. A few customers reported that Fel Pro Performance Gaskets Part Number 1604 are about 0.300 inches thick. Because these gaskets are so thick, this can create additional clearance for the baffle and for tall roller rockers.

Fel pro thick gaskets
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Stud Girdles

PML valve covers are not designed to work with stud girdles. You'll probably need tall valve covers designed to work with them.

PML Valve Cover Features

  • Strong sand-cast aluminum construction
  • Thick side walls and gasket flanges that will not bend when bolts are tightened
  • Cast-in internal baffles
  • Mounting hardware included

For a larger picture, please click one of the above images. A separate window will open showing a bigger picture. (The larger pictures take a minute to display.)

Learn more about finishes and construction of PML parts.

General Motors Trademarks are used under license to PML, Inc.