Join Date: Oct 2005
Location: Northeast Ohio, USA
Re: Ford Boy
The cam that I put into my wife's 331 stroker that I just built is a Lunati #55123 retro-fit roller cam. It has .522" lift, intake and exhaust, and 215 degrees duration intake, 224 degrees duration exhaust. LSA is 112. I got this cam because even though she wanted as much acceleration as possible she also wanted a smooth idle. Personally I like a little lope to the idle and would go with more duration like 224-230 degrees on the intake. I don't know what kind of power this makes (GT-40 X305 heads, Edelbrock Performer RPM intake, Road Demon 625 cfm carb, 9.6:1 forges aluminium pistons, Doug Thorley headers, C4 tranny and 3.25:1 rear gear, 26" tires) because I have not had it on a chassis dyno yet but I am expecting it to do well. Would do better with more duration.
I went with the retro-fit roller cam because I wanted the faster valve events, opening and closing, for more duration at lower lifts. Along with the better heads I expect this to give her an advantage over a similar flat tappet cam.
The standard duration for low end torque and smooth idle maxes out at about 220 degrees on the intake.
You always match your converter to the cam. If you are thinking about a 2500 RPM stall converter then go with a little more duration on the cam. The idea of the converter having a higher stall speed is so that your engine will rev into the begining of it's powerband before grabbing enough to launch the vehicle. The cams with intake duations in the 210 - 220 range will begin making power right off idle. Somewhere on the internet there is a chart about what RPM various duration cams have their powerband in. Maybe someone here already has that link? Increasing the stall speed on the converter is for going with a longer duration cam