[Mark Burns]

Lycoming service instruction 1125C covers the approved sealants and methods for sealing the crankcase halves.
http://www.lycoming.com/support/publications/service-instructions/pdfs/SI1125C.pdf

SI 1125C calls out "POB #4 Perfect Seal" sealing compound as one of the approved sealants. I couldn't locate any of this sealant. So I called the company which is now just called Perfect Seal. They bought POB. POB stood for "Post Office Box" ! They had trouble coming up with a name
Perfect Seal's phone number is 513-542-8444. Talk to Dave if you have any questions.

The #4 perfect seal is sold by NAPA auto parts under the Victor Reinz label.
Napa part # JV66B. My local store had to order it.

 

[gbrasch]

Thanks for the tip

I appreciate your tip. With some help I am building an engine now, and searched for this product locally, along with 2 others approved by Lycoming. Your tip led me to NAPA who ordered it for me. Thanks.