Need help choosing a cam - Pontiac GTO Forum
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post #1 of 39 (permalink) Old 05-06-2014, 04:29 PM Thread Starter
 
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Need help choosing a cam

I'm building a 461 stroker since I just blew up mine. I'm wanting a comp cam and I want the performance with the traditional muscle car sound. I'm looking for a solid loping cam.

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post #2 of 39 (permalink) Old 05-06-2014, 06:15 PM
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You will get the rough idle lope by going with a lower LSA, but if you have an auto transmission you will need a torque converter and power brakes will be starved for vacuum at idle.

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post #3 of 39 (permalink) Old 05-06-2014, 07:58 PM
 
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check out the 041 grind muscle car cam from comp cams
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post #4 of 39 (permalink) Old 05-07-2014, 08:37 AM
 
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Best thing to do is email/ call or fill out the Cam selection guides on some of the major grinders. They will almost all come up with almost the same thing. If you call first, get on crower and look at there recommendation sheet so you know the question they will ask.


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post #5 of 39 (permalink) Old 05-07-2014, 01:30 PM
 
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Look a choosing a cam like painting picture. It's hard to know what colors to use without knowing what your trying to paint. Need more info (specs) before giving advice.

I'm running a comp roller cam, that's docile enough my wife can idle it around in traffic, but also runs low 12's in street trim.
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post #6 of 39 (permalink) Old 05-07-2014, 02:46 PM
 
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I remember when I had to choose a cam.. I calculated and tested for weeks.. Bear gave me some great information and I'm very happy now.

I think something with an intake duration between 230 and 240 @.05" will work well for you, but more information is necessary like what transmission, read end ratio and information about the rest of the engine.
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post #7 of 39 (permalink) Old 05-07-2014, 07:42 PM Thread Starter
 
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I have a turbo 400 and 4.10 in the rear but I'm going to go to something around 3.24.

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post #8 of 39 (permalink) Old 05-07-2014, 07:59 PM
 
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Originally Posted by 1972LeMans View Post
I'm building a 461 stroker since I just blew up mine. I'm wanting a comp cam and I want the performance with the traditional muscle car sound. I'm looking for a solid loping cam.

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This has been discussed many times. It is just not that easy. A number of specs have to be hammered out first before you actually choose the cam. The cam should be one of the last things you select. You can get that rumpty-rump muscle car cam idle and have a dog for an engine. The rumpty-rump usually means a lot of valve overlap which in turn means a fairly high RPM running engine at the sacrifice of low speed operation which is what you will be mostly cruising in.

What RPM do you plan to spin? What horsepower/torque range do you want - lower,middle,upper? Do you have the compatible parts to spin at your desired RPM? What is your actual compression ration? Do you want any gas mileage out of it? What type of heads -aluminum/cast iron? What kind of CFM flow numbers do you have? What type intake/carb? Headers, factory manifolds, duals -what size? Transmission type? Converter stall? Flash stall? Rear end ratio? Tire size?

Not as simple as it sounds in picking a cam -parts have to match one another. And, you can have great numbers on a dyno, but have a slug once you install it and the "real world" takes over. Always build for good torque numbers with a Pontiac. Pontiac has its own unique sound and it really doesn't have that rumpty-rump sound a chevy can have because they can RPM way higher -this is why you always know its a Pontiac just from its sound.

As suggested, a good cam producer or Pontiac engine builder can help with this one. Other members, as well as other blogs, can give you advice or recommendations that have worked for them. I think cams with 112-114 LSA in the 270-290 degree duration and up around .500 gross inch lift for a solid is about right in choice. But a smaller cam might actually work best all around -and the big cubes will offset the need for a radical cam and still smoke tires. Hydraulics will be a little different choice as well as a roller cam.

I am building a .060 455CI and kinda am leaning towards the Crower #60310 solid using 1.65 rockers. The lift is a little higher with the 1.65 rockers than I would like, but the .022 and .024 lash knocks this down. I could use the 1.5 rockers which the Crower cam spec provides and drop it down to some good numbers as well. SO, when I have figured out my true compression ratio, I will then call Crower or email them, give them all the details and see what they say as to if I can use this or not for my application. Should be a real stump puller by my estimates in the build I am doing. May not work at all on someone else's ride -heck, might not be what I need either.
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post #9 of 39 (permalink) Old 05-07-2014, 08:38 PM Thread Starter
 
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Well I guess I didn't know how much went into picking a cam. Thanks for all the info!

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post #10 of 39 (permalink) Old 05-08-2014, 07:29 AM
 
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You already rec'd some good info here, but there's always the OEM selections too. Most were able to offer plenty of grunt with the stock convertors and gears. They spent millions developing an overall high performance car in most any combination. With a Turbo 400 you'd need a loose convertor for most of the hipo cams in the aftermarket. With the gear you plan to drop to you may end up with a lame combination even with a loose convertor, and to add insult to injury it would probably have an insatiable appetite for premium fuel and lead additives. I'm building a 61 Belair bubble top, and if I had a $100 bill for everyone that yells "...you gotta put a 409 in it.", I still couldn't afford the fuel!!
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