Valve Seal Conversion from umbrella to positive, BBC heads which have guides that measure: .615" and .625"

BIG BLOCK CHEVY, 3/8" X .615"/.625", set of sixteen- eight each

IMPORTANT- Be sure to read the full listing to understand required fitment information.

Since all Mark IV BBC heads came from the factory with umbrella seals and not positive type, in order to convert over to use positive seals like these, the outside diameter of the valve guide where a positive seal fits onto, needs to be measured and verified they are indeed .615" and .625"

Why is this important? Because not all mark IV BBC engines have the same valve guide seal provision diameters. This seal conversion kit is for BBC heads which have eight guides which measure .615" and eight guides that measure .625". If your BBC heads have guides of a different size, this kit is not for your application.

The most common sizes for mark IV BB Chevy is the .615"/.625" configuration but some heads have different diameter guides so it's vitally important for the buyer (that would be you reading this) to verify the BB Chevy heads they're working on actually have .615" & .625" guides. (See important Note: 1 towards the bottom of this page)

Dual Spring Warning: Check the ID of your valve springs to verify the seal will fit inside the inner spring. The seal OD is .750", the ID of your dual springs should be at least .040" bigger to provide suitable clearance.

     Specification Data:

• Fits: 3/8" valve stems
• Eight Seals will fit .615" Guides (.611"-.617")
  
• Eight Seals will fit .625" Guides (.621"-.627")
  
• Total Overall Seal Height, bottom to top: .520”
  
• Outside diameter: .750"
  
• Seal Material: Premium VITON
• Material Temp Rating: 450F
• Valve seal protector sleeve included? NO- 3/8" currently not available.

Need seals in a different size? Check our other listings, if you can’t find what you’re looking for or have a question, please use the contact us link.

Tech Info: If your BBC has guides which all measure .615", then you'll need different valve seals. For heads which have .615" diameter guides in all sixteen positions, you'll want to order # VSS-267 which are sold in pairs, you'll want to order eight pairs to get 16 seals.

Important NOTE 1: Due to the number of customers who order the wrong size valve seals and want to make a return, our policy is: Valve seals are Not Refundable. If you want to take a chance and purchase without verifying size, that's fine but if your heads are not the .615"/.625 configuration, the seals are yours to keep and cannot be returned for a refund. It's always best to check your guide sizes before ordering valve seals.