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Old 01-22-2008, 12:17 AM
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350 Cam Selection?

Hello, I have a 84 350 chevy that i am going to build up somewhat for a figure 8 race car. It is a stock bottom end with a new crank and bearings I have a set of 291 heads with 1.94/1.50 valves 64cc chambers, edelbrock performer intake and a holley dual feed 750 cfm vaccume secondaries. I have an idea of what I need but I'm not for sure. I would like to install an RV cam cause I can get a discount from NAPA or are there other cams available for about the same cost. What do I need for a duration, lift and seperation and should I change my lifters also? I need low end power for out of the corners and mid-high range power for the 75 yards of straight away and maybe I could get abit of a lumpy idle , it will be run on 87 octane pump gas. Thank You for any help.

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Old 01-22-2008, 03:50 AM
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Never reuse lifters, always run new lifters on a new cam. And when you get another cam you'll need to find a break in additive that will prevent the cam from going flat, as todays oils lack the additives needed. Since you want to stay cheap on the cam, a 224 duration @ .050 and .465 lift should suit you fine, summit racing carrys this cam with lifters for next to nothing.
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Old 01-22-2008, 08:53 AM
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I would recommend using a narrow lobe separation angle. Like 106 to 108. Better low and mid rpm torque. Plus a narrow lsa helps stock heads flow.

I would also recommend using more exhaust duration than intake duration, since stock heads typically have poor flowing exhaust ports.

A cam with 218 on the intake and 226 on the exhaust with 107 LSA would work well to 5000 rpms. Check all the cam companies for a cam like this. crane, comp, lunati, et. You could run 87 octane with 9:1 cr with this cam.
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Old 01-22-2008, 09:00 AM
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i thought 112-114? for stockish stuff. its the other way ? id keep the duration below 210 at .050 , and the lift below .450" . why not the summit .442"/.460 cam? or the crane energizer .440"/.440 ?

i would go for the performer package. the cam is all torque.

cold air and a good airbox is pretty important for pull.

Last edited by spinn; 01-22-2008 at 09:24 AM.
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Old 01-22-2008, 09:40 AM
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In general.....


110 works the best for sbc.

112 makes the idle smoother as compared to 110 and better idle vacuum but reduces the peak torque. However, it makes the torque band wider.

114 makes the idle even smoother but rely hurts the peak torque. Makes a really wide power band. Typically used with efi engines since efi doesn't rely on overlap as much to fill the cylinder with fuel/air charge.

108 increases the peak torque but also makes the torque band more narrow. Makes in the intake valve close earlier which makes it build more cylinder pressure. Will make the idle more lopy and reduce idle vacuum which isn't the best for a street car, However, power right off idle will be much better and mid range will pull harder. Extra overlap will help fill the cylinder on a carb'd engine with stock cylinder heads.


A 350 can pick up more than 50 ftlbs of torque using a 108 lsa cam compared the same duration cam using 114 lsa. However, the idle will be rougher, idle vacuum lower, and power band narrower with the 108 cam.

I recommend using the 106-108 because idle quality is not important and low to mid range power is. Plus the lower lsa will help those stock head flow due to more exhaust scavenging.

Last edited by 454C10; 01-22-2008 at 09:47 AM.
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Old 01-22-2008, 09:58 AM
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ideas

what do yu think of the lobe ramping between larger base circle cams to small basecircle. the i dea being the large basecricle cams maintain the lift and duration , but because the curves are bigger they are easier to turn...or something...

supposedly the small basecircle cams creat a small resistance due to the increased rampyness
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Old 01-22-2008, 10:02 AM
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Thanks for all the info, will an RV cam work for this application if i can find one and will the valve springs work that i have on the heads without binding or floating the heads were rebuilt 2,000 mi ago? so flat out what are the specs for the cam that i should use. what additives should be used for break in Thank You
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Old 01-22-2008, 10:12 AM
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i think the perfomer has the goods...but its a smooth drive in idle. purrs but doesnt thump.

454 is right on you will scarifice the idle quailty. hell id go for it. 108 sounds great.
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Old 01-22-2008, 10:54 AM
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i'm having trouble finding this 108 cam. i found the 218/226 but a little out of my price range can someone give me some pointers

Last edited by AR_Racing_627; 01-22-2008 at 11:43 AM.
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Old 01-22-2008, 07:56 PM
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what exactly is you price range?
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Old 01-23-2008, 07:01 AM
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If this is for a figure 8 car I would go for something with wider lobe centers (110+)and install it straight up. Nothing hurts lap times more than too much bottom end torque especially with narrow street tires. More power doesn't always equate to faster lap times unless tire spin is important to you.
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Old 01-23-2008, 12:02 PM
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My price range is around 100 for the cam cause i still gotta get the lifters another 60 or so. i run 87 octane because it is basiclly a demo derby of sorts its not suppost to be but thats kinda what it turnes into and to put loads of money into a motor that is going to be getting bashed around thats kinda nuts, so i am trying to keep it cheap most of the parts i've got for it so far have been a fairly cheap: free 750 holley (is this carb to much for what i'm trying to do i've also got a 590), 50$ intake, traded 400 block for 291 heads so as u can see it is a cheap build also for a motor that will be pushed to the limits on RPMs and heat factor. as for lap times that don't really matter it involves a lot of luck and driving skill(quick thinking). Wheel spin does help to get around the ends thats why i'm swaping out my 2.47 rear gear for a 3.73 and put 14" tires on the rear and run my TH375 in first gear full time. So really what i need like 454C10 has already established is a cam that will get me the low and mid range power and the throttle response to get up and go when i need it so far i've got the Crane 274 H06 218/218 106 lsa 0.450" 2200-5200rpm looks like a winner to me what do u think? I also have a spacer for the carb and intake would this help or hinder me?
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Old 01-23-2008, 12:37 PM
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Do you have any idea what cc your pistons are?
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Old 01-23-2008, 05:18 PM
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not at all i think the have valve reliefs in them
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