Fine Tuning a 360 Magnum with a Brawler "Double Pumper"

RustyRatRod said

Do you HAVE the 6.5 PV that it likely came with? If so, my recommendation is to try that first and see if you can tune to it. Usually, engines with low vacuum from large camshafts benefit from cruise......although that's not written in stone. So my recommendation is to try with a 6.5, then if you cannot get it like you want it, maybe look at a 12.5. Are you 100% SURE of that 18hg at cruise? That's important.

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I chose the 9.5 because when I went down to 66 primary jets (which yielded the best color plugs), it started to struggle right at 10 inches. The PV it had (6.5) really never opened it felt like. I have to really push the throttle to get the vacuum low enough to open it.

In terms of the vacuum yeah I’m certain of it being around 18. I drive on a road almost every day that is a 55 and I look at the gauge quite a bit and it’s almost always at 17-20 light throttle