Quote:
Originally Posted by Fullsize455
My basic requirements are simple: As much power/torque as I can make, while still retaining a relatively smooth idle, while keeping it "looking" stock on the outside(heads, intake, exhaust manifolds, etc), and most importantly it MUST run on 87 octane fuel all day long. This motor will be in a full size '71 Bonneville with stock rebuilt TH400 w/stock stall speed converter and 2.73 highway gears. The emphasis should be on low end torque, but with a touch of top end to throw in. Still keeping that smooth idle. No major lope for me!
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14's won't be all that hard in my opinion. I am running a very similar car to yours, and my first 455 with an ordinary flat tappet cam and 6X's with a professional 5 angle valve job and headers allowed me to run low 14's with small street rubber and 2.73 open gears. The thing is the combination of parts. Sounds like you already have a pretty good street mix in mind. I would go with the smallest Hydraulic roller you can find, one like this:
http://cranecams.com/?show=browsePar...tType=camshaft
, or perhaps the one that I'm using (a similar one if you cannot find the crane)
http://cranecams.com/?show=browsePar...tType=camshaft
if you are willing to go a bit higher in compression, but first I would give the nod to the smaller cam.
Either of those cams will idle pretty smooth (the first like a hot stocker, but much better lobes and lift), and can get you into the 14's with the rest of your parts, the bigger one will roar from an idle to 5 grand, the smaller one will pull really hard to 4,500. Either cam will FRY the tires in a 455 with 2.73 gears, even in a 4,500+ lb ride. Your problems will revolve around traction. If you are only using 87 octane, I would keep the compression ratio of your build somewhere in the region of 8.75 to one with those cast iron heads and if you decide to use premium fuel and the bigger cam 9.25 to one, and make sure your advance curve is not coming in too quick. In all honesty I would allow the cam to do the work in filling the cylinders, and they setup the compression and timing of the combination to match. Some people get fixated on using a certain compression ratio, and then matching the cam to that, but for a street torque monster in the ordinary range of a stock V8, you want great volumetric efficiency first on the low end and midrange, and tune everything else based on that premise. Getting the maximum amount of air and gas into the engine at any RPM has the potential for making the most torque at that RPM, and hence the most power at that RPM as well. That's why turbo charged cars are willing to run low compression ratios and retarded timing, but still make big power. Good cylinder filling.
Don't go with the mantra that a big cam will work as long as the compression ratio is high, not for a torque oriented ride with tall gears and an RPM limit of 4,500, it's a mistake based on following the heard. A big cam can be made to work, but by what you outlined you are looking for a superior stock range engine, and too big a cam will handicap your efforts.