I need to get a carb gasket for my W30 engine. There appears to be two types: a single secondary opening and a pair of secondary openings. Which one should I get? The engine assembly manual shows the 60335 type. Does it really make a difference?

 

I've seen similar styles/differences on other carb. base mounting gaskets. I've actually seen them provided in rebuild "kits". Honestly, I don't know the exact purpose. I read (via Cliff Ruggles) the base gasket with a single secondary opening also has those two small U channel slits to accommodate some type of weak ported vacuum used primarily for EGR functionality. Which is correct, I don't know. I suspect, but can't confirm they're both of the same thickness? Again, don't know. If the assembly manual demonstrates 60335 that would be my choice.

 

The original gasket was P/N 408597. Unfortunately today the replacement parts manufacturers have consolidated part numbers, but the consensus is that it's the gasket with the notches in the primary bores.