Quote:
Originally Posted by MikeB
Two nice things about the old school cams:
1. Slow ramps are easy on the valve train, and can get by with less spring pressure. This means they are much less likely to have problems at break-in.
2. Slow ramps typically make less valve train noise than cams with aggressive ramps. The CompCams XE series is well known for closing the valves a bit quick, resulting in some "clicking" sounds. No such issues with Lunati's Voodoo series, from what I have read on the performance forums out there.
BTW, CompCams still sells their 25-30 year old High Energy line of cams that have relatively slow ramps.
And I probably said this earlier in this thread, but for towing applications you need all the low-mid RPM torque you can get (not horsepower and more revs) and you're not gonna do that with even a hint of a performance cam.
Another quick note: The best pickup truck cam I ever had (for a truck that actually hauled and towed stuff) was recommended to me by Crane Cams back in 1995. It's their #114112. Its specs are 194/204 duration @ .050" tappet rise, .401"/.423" valve lift, and 104 LSA.
In a 350 Goodwrench engine with approx 7.8:1 actual compression, 600 cfm 4 bbl, and dual exhausts, that cam made massive torque from off-idle to 3500 RPM. The 104 LSA got the intake valve closed quickly on the compression stroke, creating lots of cylinder pressure. Vacuum remained stock at around 20". The truck would easily run at 70-75 mph up a 9,000 ft pass pulling a loaded 5x8 U-Haul trailer. Just incredible.
By the way, it replaced a 204/214 Performer cam that I had been running (virtually identical to Summit K1102). There was a night and day difference below 3000 RPM. It pretty much ran out of steam at 4000 RPM, but in hauling and towing applications, who cares?
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Agreed on everything you said except the implication (which I may be reading in to what you said) that fast ramps are somehow a performance cam, so not good for towing. Performance cams are high lift, high overlap, etc, etc., and are indeed unsuitable for towing. A performance cam may or may not include fast ramps, but fast ramps are independent of whether or not it is a performance cam or a towing cam, or a general-purpose cam, or whatever.
The reason you can get away with fast ramps now is that computers can calculate the cam lobe-lifter pressure at any point in the cycle, at any rpm, for any cam lobe design, and so it is a lot easier to get fast ramps without going "over the edge" and causing the issues you mention.
The 12-300-4 generates 420+ lbft of torque at 2500 RPM, and has 300+ lbft from 1000 rpm all the way to 4600 rpm, with a stock lift and fast ramps. That is my recommendation for anyone doing towing or plow work. I've had it in my truck for three years now and love it. No issues with it at all.
The 12-230-2 has the same bottom end torque as the 12-300-4 with more horsepower up top, but it does this with a 10%+ higher lift. I stayed away from it for the reasons you cited. Fast ramps is enough "extra" without 44-degree ramps pushing a .430-.440 lift.