Replaced 2bbl with 4bbl Rochester on 86 43 OMC

I just replaced my 2bbl roches

I just replaced my 2bbl rochester with a 4bbl rochester and manifold on my 86 4.3 omc (just wanted the 30 more hp.) Got a Napa Marine rebuilt carb and used manifold. Idles great. The secondaries don't always open on acceleration. Sometimes there is some wavering of the engine at WOT-feels and sounds like slight cavitaion. Any suggestions?

"I'm interested in doing t

"I'm interested in doing the same. How did you spec out the carb? Is it the same as a V8, or did you just ask for a carb for a 4.3?"

"I asked Napa if they had a ma

"I asked Napa if they had a marine parts line, they do, all though it is somewhat limited.The used manifold is actually a Mercruiser manifold but 4.3's are GM anyway. The carb was listed as a Marine replacement for 4.3 mercruiser. After installing carb,I advanced the timing while running until pinging on acceleration, then backed off until no more pinging. Closed the fuel/air mix screws at idle until it slowed rpm then opened 1/2 turn. Now it idles and runs great. The secondaries open up on acceleration which is were you realy feel the increase in power. Still having some slight engine wavering at WOT. I just ordered the Haynes Rochester repair manuel to see if I can solve the wavering problem."