Hello looking for a little help with a Holley 750 cfm. I am in the process of installing a 144 weiand blower on my SBC 350 and I am wondering where I should start with my primary jet size any help is greatly appreciated. I was told to start around 84 seems high but this blower system is all new to me.

You are going to have to post a lot more detailed information before anyone is going to be willing to venture a guess, and even at that point it is just an educated guess. Things like cam, heads, exhaust, compression ratio, etc. One can assume that you are installing this on a stock 350, but you know where assumptions can take us. At the end of it all, if this is a build that you want to dial in right, running a wideband O2 sensor with an A/F meter is the only sure way to get it dialed in correctly. I'm not experienced with running superchargers, perhaps some of the OSO'ers with boost experience will chime in if you fill in your details. good luck!

Sorry it is a stock 350 with low hours, just trying to get 4-5 boost. Also I am not looking for the exact jet just looking for a starting point.

84 is rich but I would start with it. This assumes the power valve is plugged, so you would have 84 pri and sec with plugs in both, no need for power valves unless your boat is real light (can cruise in vacuum under blower).