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Parts are on order to resurrect the comet from it's vandalized sorry state. I need some input on the cam. It'll be a 331 stroker with eagle crank and rods, je forged flat top pistons. Heads are heavily ported 351 windsors with 62cc chambers. Car has no power brakes and will have a 5 speed with 411 nine inch rear. Use will be street/strip duty. I'm thinking hard about a retro-fit roller kit from crane, but I'm not sure about the cam itself. I'll call a couple of the manufacturers for input, but you can't beat tried and true experience. I'm planning a self imposed redline of 7000 rpm. Should I go solid or hydraulic roller, flat tappet, lift, duration, etc? Ok experts, whatchathink?
 

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I might be wrong but if you go with the crane roller conversion aren't you limited to the cams crane has made to go along with this conversion ?(which I think are pretty limited)
 

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Your 7000 RPM redline pretty well limits you to a solid cam of some kind. If it was 6500 RPM instead a hydraulic could be made to work well as long as careful attention was paid to spring selection and valvetrain weight, but it pretty hard to make hydrualic cam, especially hydraulic rollers work good above 6500 RPM.
 

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So...from a reliability standpoint, perhaps I should limit my redline to 6000-6500? This is more street engine than drag engine and I don't want to go nuts on a huge cam that I can't drive to local cruises or shows. Still, the temptation to be able to dip into the 11's is awfully strong
. I've looked at project 11.99's choice of cam and it seems to be more what I'm aiming for. Editors, you can chime in here anytime..!!
 

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Just because you want to run 7000 RPM and into the 11's and need a solid lifter cam doesn't mean the engine won't be reliable. In some ways the solid is better than a hydraulic cam. They will produce better idle vacuum and more low end torque than a hydraulic cam that makes the same HP. They simply need to have their lash adjusted occasionally, that's all. There are a few cams out there that are designed for street and strip and would do the trick for you. There's the CompCams 282S Magnum Solid (236-236 .528-.528 110 l/s +4) or you could get CompCams to Custom grind one of their new Extreme Energy Mechanical Flat Tappet SBC grinds on a SBF blank. The XS274S-10 grind (236-240 .534-.544 110 l/s +4) would work well. Crane also makes a grind that would work well but would be slightly more streetable and produce a wider powerband. Their Powermax F-278-2 (238-248 .512-.533 114 l/s +5) With 10 to 1 compression, decent heads, a Vic JR intake, 750 carb, 1 5/8" minimum diameter long tube headers and a good 3" exhaust any of the above cams can make 400 reliable HP without the added expense of a roller cam. I hope that helps.

<font size=-1>[ This Message was edited by: mach1morgan on 3/12/02 6:24am ]</font>
 

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AH! At last, somebody gives me some part numbers and lift and duration figures. Mach1morgan, thanks!! I'll call up the cam folks tomorrow!
 

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I believe that the Crane Cams retrofit roller setup utilizes a reduced base circle cam to enable fitting the longer lifter assembly into a flat tappet block. Check with Crane to be sure. If I'm correct, you must either furnish this information to your cam grinder or buy it from Crane. I'd personally stick with the same manufacturer for cam and valvetrain, IMHO. Crane should be able to grind something custom if their off the shelf grinds don't work for you.

I'd highly favor the roller set-up versus a flat tappet, either mechanical or hydraulic. The additional area under the lift curve increases breathing, meaning you might get the nearly the same power at 6500 with a roller as at 7000 with a flat tappet, with better drivability and reliability.

It's your motor, and you should run it any way you please, but 7000 rpm is very, very tight for a street driven set-up. The life of the motor, in street terms, will be very short...unless you put mega dollars, and mega building skill, in every step of the build-up. Why not build a 6000 -6200 rpm motor with the reliability of a hydraulic roller, and set it up for a big, fat, wide torque curve? That is something that you'll enjoy and feel at every stoplight, rather that only occassionally when you rev it for all it's worth.

You ought to be able to get around 360-375 h.p. with that 331 in a state of tune that's a blast on the street and stone reliable; to get to that 400+ range the drivability and reliability (or cost) suffers significantly. Your money; you chose.

I'd highly recommend that you choose your cam LAST when planning your build-up. Select intake manifold, carb/EFI setup, headers, heads, compression, gearing etc. that all work well together...same rpm range. THEN call your cam companies, and/or get some input from someone with dyno software. Given modern grinds, there's is no such thing as a "great" cam or a "bad" one. It's all about selecting what best matches, and optimizes, the rest of your breathing combination. If there were one "magic" grind, everyone would make it. Food for thought.

Steve Amos
 

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I built a 306 with the 282S cam. Its a sweetheart on the street and revs to 7k at the strip. Cheap too! Great little street/strip cam. Nice rumpity sound at idle.
I have an Ultradyne solid flat tappet in my 331. The specs are [email protected], and .562 lift. This is a very streetable cam and helps make great top end power. This is not a cataloged cam, its one that I had ground.

<font size=-1>[ This Message was edited by: 85Mike on 3/12/02 11:07am ]</font>
 
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