lunati bracketmaster II ??

[kamkam1]

Hi all, Who's using the lunati bracketmaster II cam 300/300 adv.duration and .515/.515 lift ? Do you like it and what's you combo. The reason I'm asking is because I wiped a lobe off my Chet Herbert cam and I can get a deal on the lunati from a good friend. My combo is 355 cu. .125 dome speed-pros, 441 heads, weiand 7546 manifold, hooker super-comps, 10 inch convertor, th 350, 373's in a 68 swb. Comp-ratio is about 9.3-1, is this cam to BIG ??

[lowriden58]

that cam sounds a bit on the large side for your setup IMO. also i would stay away from a 300/300 type duration. you want more of a "split" duration. like say 284/296 or so to get a nice choppy idle

[Alex1]

what is the duration at 0.50?

[kamkam1]

Thanks for the replies. Duration @ .050 is 246/246. The cam thats in the engine now is 228/234 @.050 and .480 int./.494 exh. Chet Herbert brand. I like this cam alot,it sounds wicked and pulls awesome, but #7 exh. lobe has been rounded off. As I said the lunati is brand new cam and lifter kit for $50.

[lowriden58]

that lunati cam wont sound anything like what you have now. as i stated above you need a split duration to get that nice lope

[Alex1]

This one will have a rougher idle. For $50 - I would try it.

[swb85]

Having a split duration isn't what gives a cam a lopey idle, it's the amount of valve overlap (amount of time int/exh valves are open simultaneously). I guarantee you that 246/246 lunati cam will sound nasty.

[Marv D]

Kirk, We ran that Lunati #00012 cam your looking at in a buddy's street strip car. He had WAY more engine than you, and trust me,, it WILL be WAY too much cam for your combination IMO. I built Dana a 408 (400 +.040), Edelbrock 170cc E-tec heads, set compression right at 10.5:1, used a Edelbrock Vortec RPM air gap intake, One of Patricks XC carbs, Supercomps w/ 3" pipe through series-40 3" flowmasters., cheepie Jeggs 3500 stall convertor and a TH350 trans... Dana could drive 100 miles to Speedworld, change on a set of 27" slicks, click off 11.20's @ 117 in a 74 Nova , and then drive 100 miles home. That car was simply a freek of nature IMO.

Notable about all this... Vortec / Edelbrock E-tec heads are weak on the exhaust side and 'SHOULD' demand a split patern cam for (how is it they put it) for best performance. Just goes to prove that trying something 'different' isn't always a bad move. If you can afford to experiment, that's the only way you find things 'better'. But be prepared to have a 'Wall of Shame" for all those ideas that didn't work out so well.

With all that said, listen to swb85 is telling you,, It is valve timing that causes the cylinder to 'slobber' fuel and have inconsistant idle (lope). that cam is going to be a WILD sounding cam in a 9:1 350. Hope you don't have power brakes, or care about bottom end torque. Large cams like this have a late intake valve closing (even tho the #00012 is 4 degrees advanced) That generally causes a lower cylinder pressure (which is why it takes more static compression to support a long duration cam). Here's a link to the cam card for that #00012 cam. Liek swb85 said, look at the overlap of the intake valve opening before the exhaust valve closes. Intake opens 19° before top dead center, but exhaust doesn't close till 11° AFTER,, there is 30 crank degrees of both valves being open 0.050" or more. The overlap does a couple of things. It takes advantage of the exhaust flow out of the chamber to initialize flow of intake into the chamber. Of course at low engine speeds the exhaust isn't exiting the chamber at such supersonic speeds so some the the exhaust reverts up into the intake, spoiling the mixture, causing lean / inconsistant misfires at idle,,, aka LOPE. Go take a look at some of these "Thumper" cams and look at the overlap on those,, VERY much like this Bracket master!

As a BTW, what lowriden58 is saying (I believe just slightly mis-stated) is that a cam with a split duration typically has more exhaust duration, and in that ,,typically has the exhaust valve opening sooner (being a larger duration). Depending on how the cam designer decided to set up the lobe seperation, this WILL have an effect on how the cam sounds. The exhaust tone we hear is the expanding gasses escaping past the exhaust valve. If you have more exhaust duration, it only makes sense that you have to open the valve sooner. Opening the exhaust valve sooner is akin to opening the door in an explosion,, the more of that explosion is going to rush out the door instead of building up pressure INSIDE the chamber. Less pressure , less exhaust tone or 'pop' to the exhaust. The flip side of that is opening the door sooner allows more of the explosion to rush out and not put pressure on the piston. Exhaust valve timing has a HUGE effect on the sound we hear in the exhaust. Wether it will be crisper, sharper, louder, milder,,,, or in a direction you are looking for,, well get ready to hang some parts on that 'wall of shame' it it isn't

All this rambeling aside,, I am a HUGE opponent of using ANY used flat tappet cam. You have already lost a lobe or two in this motor. That debris from the lifters and cam is embedded in all if the engine bearings. That's the bearings job. The metal ground away from the cam and lofter is hard, VERY hard,, much harder than your crankshaft (assuming this is a cast crank) While your running this motor now with all these tiny particles embeded inthe bearings,,,,, it's slowly grinding away at the crankshaft. As you have proved, keeping a flat tappet cam alive these days (with the CRAP they are selling us for oil) is a hit and miss proposition. Your going to take a chance of sending MORE debris through the motor,,, over a couple of hundred dollars for a cam kit (new with liftrs). Not me,, no thanks! In fact I'd be pulling the motor to freshen the bearings, and then saving for a a hydraulic roller cam package.

[kamkam1]

Thanks for your replies. I am going to pass on the cheap deal and go with something milder.

[Outlaw72]

I had this exact camshaft in a SBC 408 and it was great other than the fact it needed an extra vaccum pump for the brakes. Vaccum is horrible...