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Don't shoot, Cam Selection ??'s 302 Ford

Discussion in 'The Hokey Ass Message Board' started by Malpass, Nov 5, 2010.

  1. Malpass
    Joined:
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    Malpass Member

    Hey,

    I suck at selecting a cam, this is a black art and full of VooDoo as far as I'm concerned. I just don't understand how to put together the right lobe sep/duration/lift, etc.

    let me me give you my details. '62 Fairlane (3500lbs) 302/stock heads with new springs and roller tip rockers, right now I have the Edelbrock Performer 289 intake. hopefully upgrading intake to an air gap or at least Performer RPM or something similar manifold, Edelbrock Performer 650 carb. C4 w/shift kit. 3.56 (or 3.50) rear, hard to read the tag.

    I want to get my best performance out of this motor that I can. It will be driven on the street, but I want to see some power out if it. In it's current state shes kind of a pig. it has a little cam in it now, but I have no idea what it is, it doesn't sound like much. the PO installed it and I don't have the cam card.

    I do not want to run a stall converter, but i want a nice chop to it.

    Hit me with your best suggestions.
    Last edited: Nov 5, 2010
  2. Francisco Plumbero
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    Francisco Plumbero Member

    If you go too large you will have vacuum problems on the c4 I have this monster freakin honkin cam that only allows me a vacuum of 11. .540 .544, not fun with a street auto matic, any time I adjust anything that affects vacuum I have to jag around with the adjustable modulator, jack the sucker up secure it turn a 1/4 turn drop it run it over and bloody over again, it's gettin old, I may just take the bite for 30 HP and downsize my cam to something in the .480 .490 range that will hold a nice operating vacuum of more than 16 or 17. I've had a few 302's in that range and they were plenty street stout with out the tuning problems. c6 2500 stall 323 rear gear. If you have a manual valve body this may help with the trans fun. Mines on the column, sucks to operate a MVB up there.
  3. TexasHardcore
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    TexasHardcore Member

    You'll get nothing but varied opinions here. Cam profiles are a foreign language to me too. Best bet is to call a cam grinder and tell them what you just wrote. Call all of them, get their opinions, then make your decision.

    I use Comp Cams "Cam Quest" software to figure out the best cam for my combination, then call Comp and talk to their tech guys about the cams recommended by the software. Talk about their pros & cons. Then I research other brands cams that are comparable, talk to their tech guys and then make my choice. I spoke with Ed Iskendarian over the phone once...as well as Chet Herbert over the phone when he was alive. Pretty cool to talk to the dudes who's names are on the cams...freakin legends.
  4. smokey3550
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    smokey3550 Member

    Comp's thumper cams have a choppy idle without using too much duration for a street/ auto combo. Dont go over 270 duration. Comp uses a tight LCA to get their choppy idle. They will make great power as well.
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  5. propwash
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    propwash
    ALLIANCE MEMBER

    call your supplier - that's their scope of business. Tell them what you've related here, and I'm sure they can get you started in the right direction.

    do NOT overcam your engine.....

    dj
  6. Malcolm
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    Malcolm
    ALLIANCE MEMBER

    What year engine and heads are you using? The heads and compression ratio will certainly make a difference in your cam selection. Depending on your engine and cam selection, you may need to check piston-to-valve clearance, also.

    You mentioned new valve springs. Do you have the specs. on them?
    I installed the Trickflow "Stage 1" roller cam in my last 302 and didn't change the valve springs. Learned the hard way on that one. Valve float ruined a bunch of the valve stem tips, among other problems that were caused by not having springs matched to the cam.



    Malcolm
  7. JDW
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    JDW Member

    You might just be shoveling it against a tide. While you can throw a cam at the engine and hope for the best, an early 302 needs more then that. Some of the heads that Ford supplied for the small blocks were - to be nice about it, junk. Little valves, not enough intake or exhaust passage size then of course, then some had big EGR bumps in the exhaust to further restrict the flow. Of course the 289 Performer intake - that gags it even more. A 650 carb is too big as well. Use this formula for a street carb:[FONT=Arial, Arial, Helvetica]

    cfm = rpm x displacement / 3456 x .85[/FONT] ( It ends up being a LOT less then a 650)
    5000 x 302/3456* x .85** = ~372 cfm !!!!

    *3456 is a constant (cu ft per minute 12x12x12x2)
    **.85 is volumetric efficiency (street engine in good shape)

    Now, back to your original question about camshafts - with stock pistons, you will be limited to about .500 lift and 1.6 ratio rockers - you need either eyebrows cut in the heads of the pistons or replacements - but you need a PLAN and know what you have first.

    I guess this is where I would start:
    --Heads - GT40P off an Explorer (need springs and hardware to match the camshaft)
    --Intake - Performer RPM (an air gap - waste of money for a street engine)
    --550-600 cfm carb
    -- Camshaft - I would go roller. Too many problems with flat tappet camshafts due to lack of oil additives these days. Ford has some nice offerings for them. I'm using their 'E' which has a nice lumpy idle.

    Have Fun!!
  8. Malcolm
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    Malcolm
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    ^^^ I disagree with the use of a Ford Racing camshaft. I believe most, if not all, of them have the same lift/duration for intake AND exhaust. Other cam companies, such as Trickflow, have better cams with a 'split duration' that make up for the weakness on the exhaust side of the Ford heads. Of course, it does depend on what heads you are using.

    The Weiand Stealth is also a good intake, from what I've read. I actually just got a good deal on a used one on Ebay for the roller cam 302 that I'm building right now.
  9. 1957Custom
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    1957Custom Member

    The last smallblock I built had a Performer intake stock exhaust manifolds & a 268H Comp cam. Had good vacuum, a good idle, good performance, & good economy to boot
  10. RileyRacing
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    RileyRacing Member

    FWIW, I have a similar engine (stock 85 truck 302 long block) in my 87 Mustang LX convertible. The engine has a Stealth intake, Edelbrock Performer cam, Summit roller timing chain set and box stock Holley 600 and with a T5 will pretty much burn the tires at will through first and second gear. So, I'm sure I give up at least 5-700 pounds compared to your car, but the performance would still be good for you. The parts were all close to or free when I started putting the car together, hence why they aren't paired or comboed up. If you can get in with the local 5 point oh guys, they usually let stuff go for cheap, around here in Metro Detroit anyway.

    My two cents, of course, your mileage may vary.

    JK
  11. Dolmetsch
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    Dolmetsch Member

    Let me remove the voodoo then.
    You have lift and duration. Duration controls the RPM. How high to you want to turn it or where do you want your HP peak? Once you know that it can be easily figured out. LIFT. Valve lift is nice but what the cylinder heads want determnes best lift. Ie if a head flow peaks at .540" there is no point giving the engine .600 lift. In fact it will often kill the power since above best flow as lift is raised some heads go into turbulance and airflow plumets so you need to know head airflow. Even if you havent flowed your heads someone more than likely has flowed some the same or similar and charts can be found . If it is a street machine. I like to always at least have just over .500 lift.
    That leaves lobe centre. A tight lobe centre is peaky an wider one spreads it out a bit. Here you could cheat by looking in a cam manufacturers book. If all the cams made for your engine are 110 lobe centres or even 90% are then that would be the place to start. If all are 108 then you know fairly certainly that that particular engine favours a tighter lobe centre.
    Hydraulic. best performance under 7000 RPM . Useless above as hydraulic lifters cant operate any faster than that.
    Solid . Only reason to run solid is RPM above 7000. Otherwise you are running it just so you can say i have a cam and solids but you probably are costing yourself power. Why? Glad you asked.
    Suppose we have two cams with indentical specs but one is hyraulic and one is solid. lets say for this example they are .500" lift and 280 duration.
    If you choose the hydraulic you will get .500 lift at the valve(minus about .006" fudge factoras the lifter sucks up the sudden shock of movement. You will also get almost full use of the 280 duration .
    On the solid if we look closer at the specs it will say in almost all instance "valve lift at zero lash"Well Virginia solid cams do nt run at zero lash. for some .028 and .032 were normal settings. So we would have .500" valve lift minus .028" =.472" on intake and .500" - .032 = .468" on exhaust.
    dont believe it? Check your specs. One company gives a more realstic approach but only one I know of.
    And the duration needs a look at as well because we have to get that lifter moving ever so slowly at first to takeup the lash and carry it to the pushrod without wiggle or bounce till it takes up the slack. That eats up about 7 degrees . Same at the other end we have to set thevalve s dwn carfully and get the lifter back in the unloaded zone carefully so it doesnt bounce . There goes another 7 degrees. The hydraulic does not have this problem significantly.
    Roller is wonderful and wonderfully expensive. They will however do things so quickly that they can be made to really perform and because of that will generally make the most power. Also they do not have break in problems BUT breaking in flat tappet cames or flat tappet hydraulic cams is not impossible. One just has to follow ALL the rules not just some.
    Don
    Last edited: Nov 6, 2010
  12. Malpass
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    Malpass Member

    thanks for the tech lesson Don!! I really appreciate that!

    The heads are pre '77 302 heads (58cc 1.78/1.45 valves)
  13. Francisco Plumbero
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    Francisco Plumbero Member

    Do these heads have press in rocker arm shafts or threaded? One thing is certain, the bigger the cam on a 302 the more associated hardware you will have to up grade to keep it in the car and the less street drivable it will be. Go conservative on it or in the end you will have 10 grand into what, a 302. God I wish I had heard that on my first 302 build.
  14. Malpass
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    Malpass Member

    I'l have to check and see on the studs, the PO did all of the work, I hope with roller tip rockers they went ahead and sprung for the screw in type. Sounds like I need to upgrade the intake and go from there.
  15. studeboy
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    studeboy Member

    Please keep this updated as to your updates. I'm curious to see how this comes out as I have a similar combo for my shoebox.
  16. Malpass
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    Malpass Member

  17. Falcon Gasser
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    Falcon Gasser Member


    Very good combo:rolleyes: I liked the Edelbrock Performer cam with the Performer intake and the 600 c.f.m. carb, I used a Edelbrock and a Holley and did not find any difference with either one when they were tuned in. I used it in a street driven 65 Mustang with a 302 and stock 66 289 heads 3.55 gear and C-4 trans with stock stall and it was a great driver combination with good power.

    Jon
  18. wisdonm
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    wisdonm Member

    Thanks for that explanation Don.

    I don't want to steal this thread but I do have a question. I have a '68 J code 302 block with 42,000 original miles. Unfortunately, I believe it has the wimpy stock 289 rod bolts. What is the safe red line for these rod bolts?
    Last edited: Jun 23, 2011
  19. George/Maine
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    Mid Coast, Maine

    George/Maine Member

    I bought a truck and it had idle problems had 14 lbs vaculm,you had to keep foot on gas and brake to slow down,It had a c4 auto trans.It had stock convetor.I replaced carb,timing chain,dist,still wouldn,t idle down.Sounded like a boat.
    I couldn,t stand it any longer and odered a
    Edelbrock Performer plus cam kit.
    EDL-2122 $145.00
    Someone put a hot cam in this 302, now it idles good, just as much power and smooth idle.
    You get cam and lifters.
  20. Mark T
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    Langhorne, PA.

    Mark T Member

    I've used this cam and was very happy with its performance, it sounded good too.
  21. 26 roadster
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    26 roadster Member

    I like the ford motorsports 290/310 hydraulic cam, but all my cars are lighter. It has a nice idle and I don't need a stall converter
  22. torino_Joe
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    nickle_nickle_9,CALIF

    torino_Joe Member

    I had a Ranchero with a pretty similar set-up,c4 with a shift kit,302 8.5:1,gasket matched 62cc heads,accel dizzy,coil,and wires,roller rockers,upgraded springs,headers,performer rpm manifold,600 holley with a one inch spacer,double-roller timing chain,with a Crane 228/228 dur 512/512 lift.The car had 3.08s and was about 3400lbs with 265/60/15s.
    It was a bit slow off the line with no stall converter and tall tires,but man that thing came on @ 2500rpm and pulled HARD to 6200.Great idle not to lumpy but you definitely know it's not stock.Beat a supercharged 4.6 Saleen mustang and bitched out a Ford Lightning!!!!
    Not to bad......

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