I need a good cam recommendation

Discussion in 'Street/strip 400/430/455' started by mechanic58, May 25, 2019.

  1. mechanic58

    mechanic58 Clover, SC

    I’m sure there’s dozens of threads with this same subject, but each engine and application is different. I have built more engines than I care to recollect, all types, but I haven’t built very many 455 Buicks.

    My engine is .030 and is going to have right at 10.0:1 compression. I plan on running a B4B intake and headers with a nice free-flowing exhaust. The car its going in is a ‘66 Skylark with an automatic. I’m not opposed to running a looser converter and changing the gear (car has 2.73’s now, thinking about a 3.36).

    I want to be right around .500” lift because I’m not interested in too many costly valvetrain modifications. The heads are stock closed chamber castings that have had the ports cleaned up, nothing major.

    I want it to sound good - nasty - and pull like a mf’r from mid to upper range. There’s just so many grinds and so many that are very close together that I can’t decide. I don’t have enough experience with these engines to know what they like best. Any help is much appreciated.
     
  2. mechanic58

    mechanic58 Clover, SC

    I’m thinking TA-290-94H, but I’m not sure. I know the 112° sep will sound better, but the TA-288-94H also looks good but has a 114° sep.

    I can’t decide!
     
  3. mechanic58

    mechanic58 Clover, SC

    I’m guessing these engines probably like a narrower lobe sep, but I’m just not sure.
     
  4. FJM568

    FJM568 Well-Known Member

    I'm running the 288-94 with a 71 455 stock bore, stock heads, stock manifolds, 2.5 in exhaust with x-pipe, TA1607 cast pistons(10:1), steel shim head gaskets, B4B, QJet, TH350 with about a 2000 stall, 3.08 posi 8.5 rear in my 66 Skylark. Compression calculated to be 9.5:1. Last year in BG @ the Nats, it ran a best of 13.5 @ 102.79. On street tires. There's a little more in it. Need to mess with gov a little more. It's shifting at about 4500 right now. On that pass, I let it upshift 1-2 on it's own at 4500, and I manually shifted into 3rd at 5000. Need to tweak gov to shift at around 5000-5200 and get me some slicks/DRs and I should have a high 12 in it. It's a good cam, enough vac for power brakes, and a little bit of an idle just to let you know something's there. Whatever cam you pick, just make sure you match it to your static and dynamic compression ratios. My motor was a little lazy originally with the stock 71 pistons and Felpro head gaskets. Changing the pistons to the high compression TA1607 and steel shim gaskets brought my static and dyn comp ratios up, and woke the engine up.

    Good luck on your build.

    IMG_20181026_130241.jpg

    Be aware that headers are going to be a tight fit, unless you're running Stage 2 heads on a 66-7. You won't lose too much by running stock manifolds.
     
    mechanic58 likes this.
  5. Bigpig455

    Bigpig455 Fastest of the slow....

    Any good running 455 has 12's in it. Shift points are key, so the governor mods are a good idea. Lots written about that on the board here.
     
    matt68gs400 likes this.
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Any discussion of cam selection should consider Dynamic Compression Ratio (DCR). Read through this,

    http://www.empirenet.com/pkelley2/DynamicCR.html

    At a true 10:1 Static Compression Ratio, you'll want to be careful with cam selection keeping the DCR closer to 7.5:1 so it will run on pump gas and decrease the tendency of detonation. Some guys have had success downloading and using the calculator at the end of the above linked article. Others, not so much:). Not sure why, but lack of computer savvy might have something to do with it:)

    An alternative is to figure out the intake valve closing point by simple formula, and then plug it into an online calculator.

    Simple math to find the closing point..


    To find the timing events for the intake:

    Divide the Advertised Duration in half and subtract the Intake Center Line from the remainder.

    That will give you the opening event. Intake Opens Before Top Dead Center (BTDC)

    For the closing event subtract 180 from the duration and then subtract the opening number from that sum.

    That will give you the closing event. Intake Closes After Bottom dead center (ABDC)

    Then plug it into this calculator (Disregard the .050 + 15*)

    https://uempistons.com/p-28-effective-compression-ratio-calculator.html

    Let's use the popular TA C118 cam from TA

    Specs are 276/295 advertised duration, 118 LSA. Advancing it 4* would have you degree it to 114* Intake Center Line (ICL)

    So the math is,

    276/2 - 114 =24* BTDC intake opening

    276-180 -24 = 72* ABDC intake closing

    Plugging that into the online calculator,

    DCR118.JPG

    7.5, right at the lower end of the desired range for pump gas. Advancing the cam closes the intake sooner increasing DCR, retarding the cam, closes the intake later, lowering DCR.
     
    Last edited: May 26, 2019
    matt68gs400, Julian and mechanic58 like this.
  7. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    The 290-94H figures in at 7.436

    The 288-94H figures in at 7.368

    Close enough to the 7.5

    If you go to a smaller cam, you can raise the DCR, but with iron heads, you might have some ping, or not. Depends on how hot it runs among other things.

    The DCR in my current engine is 7.84, but the aluminum heads make it more tolerant of octane. It easily runs on 93 pump gas. Never tried anything lower octane. I do run some Race Gas at the track where it will be at WOT for extended periods of time.:D My Static Compression Ratio is 10.53:1
     
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  8. 67Skybird

    67Skybird Josh - Minnesota

    Thank you for that Larry. I read the dcr info when you posted it on a thread regarding my build. I was going to ask about some of the specifics on your engine, but you answered most of them here. I assume this dcr is with your 600hp engine, one question I have is how much port work you had done? You dont have to go into too many details, level 1, 2, or 3 will suffice as I continue planning my own build.
     
  9. mechanic58

    mechanic58 Clover, SC

    Thanks for all the feedback.
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    My aluminum heads were purchased through Greg Gessler back around 2006 or so. At the time, Greg's level 2 port work was the entry level porting, level one being his standard valve job. I recall it costing me about 300.00 above the cost of the bolt on heads, which for me, was a no brainer. Greg also milled the heads .040" so that my SCR (10.4:1) would be better for the aluminum heads. My iron engine with the 118 cam was 9.4:1 SCR. The .040" off made for 59cc chambers, and the flow chart showed 313/225 CFM @ .550 lift. When all was said and done, I picked up 1.1 seconds and 11 MPH at the track.

    HeadFlownumbers.jpg
    Around 2010, I decided to have Jim Weise build a short block for me because I wanted to try a bigger cam, but my iron short block had pistons with no notches for valve clearance. I took the aluminum heads, SP1 intake, and AED 1000 HO carburetor, and sent them to Jim. I bolted my iron heads back on with the Performer intake and Q-jet, and my GS was operational while JW built my engine. This turned out to be the right choice as Jim had some problems with my original block and that necessitated him building a second engine with another block. In any case, Jim did some additional porting to my heads. The chambers ended up at 61 cc, and my flow numbers improved to 334/250 @.600.

    Stage1SEheadFlow.jpg
     
    Last edited: May 26, 2019
  11. 67Skybird

    67Skybird Josh - Minnesota

    Thank you Larry. I appreciate how open and willing to share you and the Buick community are.
     
  12. mechanic58

    mechanic58 Clover, SC

    Just FYI - my car will not be a daily driver or a race car, its strictly a toy. I doubt I’ll ever put 5k on this engine.
     
  13. Thumper (aka greatscat)

    Thumper (aka greatscat) Well-Known Member

    Sandy's combo in her GSX is as follows.
    Iron stage 1 heads,9.75 compression forged piston, iron intake and exhaust manifolds kb118 hyd cam, 69 rockers,double roller chain ,oil mods,Qjet,stock distributor with points eliminator total timing 30 deg.all in at 2600 rpm.3000 comverter,3.42 gears governor ground for 5000rpm shifts. Daily driver has been driven to Columbus,Indy and BG then had the snot beat out of it for 3 days and driven home.runs 12.7's all day on sticky tires.keep it simple ,pay attention to detail and combo.
     
    Last edited: May 26, 2019
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  14. mechanic58

    mechanic58 Clover, SC

    I’m probably going to go with the 288 cam after studying. I think it will work best with my setup.
     
  15. 87GN_70GS

    87GN_70GS Well-Known Member

    Careful with that simple IC calculation in lieu of the timing card. It's only correct for non-symmetric cam profiles. which are in the minority these days.
     
  16. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Thx Scott, good to know. How big an error could that possibly create?
     
    Last edited: May 28, 2019
  17. 87GN_70GS

    87GN_70GS Well-Known Member

    I'm measuring mine, its a custom Bullet HR, it varies lol. But the biggest difference is from the very top to advertised. So when I measure 0.050" down from either side of peak lift, and compare that ICL with the advertised ICL numbers (0.006") I get a 4 degree difference in those 2 numbers.

    It would've been only 3 degrees difference but they made the cam with 2 more degrees duration than spec skewing the diff by another degree.

    The difference between max lift and the ICL obtained by the 0.050" numbers is 2 degrees
     
  18. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Well, in the absence of a cam card or degreeing equipment, I suppose we need to use what we have to get a ball park DCR.
     
  19. matt68gs400

    matt68gs400 Well-Known Member

    0D29887E-FCCA-4824-AAB9-03760FFCBCE1.jpeg I’ve got a 288-94 on a shelf that I can’t use. I did buy it used off this site from someone Who used it for an engine break in Been sitting in a sealed bag with oil.
     
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