Holley carb jetting advice

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Also, Check your oil level, and smell the oil, - if it's dumped a ton of fuel down the carb, You're gonna hafta change oil after you get this sorted out .. It's going to be contaminated with fuel,, and will be blowing gas fumes up the PCV, making it dificult if not impossible to set mixture screws..
 
I have a 408 ci magnum engine very similar to yours. Mine has RHS magnum heads but probably flow close to yours, same duration cam, 10.8 cr. The diff is a Holley 870 street avenger carb. It was/is dyno tested and driven in ND. Jetting initial 82 prim/78 sec. After setting A/F ratio during dyno pulls it is at 78 prim/78 sec. It still is a little rich but I drag race it more than street time. Tuner said carb is a little big could use 770 cfm, but I don't want it to go lean. Good luck
 
Yeah, I know my expensive Amsoil is fuel fouled. That sucks. I talked to an old acquaintance, Pat from The Carb Shop. He really would want my dyno sheet to know for sure, but he says probably a 72 primary and not to worry about the secondary. He also said to go with a 4.5 power valve. I don't know my vacuum, but once running I guess that would be easy to check. I am ordering my MSD programmable today as well. I am going to dial this beast in.
 
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