XR274HR-10 in 318

Small Block Mopar Engine

  1. JoJo

    JoJo Well-Known Member

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    I was wondering if anyone ran this cam in their 318 or do I need to go with another cam choice...

    My Setup: '87 Roller 318, Edelbrock 750, Weiand Action+Plus Intake, 302 Casting Heads, HEI Distributor (Have A Unilite Also), Shorty Headers, A904 with High Stall & Low First Gear Set, 3.55 Gears

    I have my eye on an FTI 9.5" 3000-3200 Converter as well.

    Is there anything in particular I need to look out for while trying to give my little 318 some extra HP?
     
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    • 273

      273 Well-Known Member

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      Anything done to the heads ?
      What CR ?

      You might be better with a cam size down, if you do go with it, interested how it turns out.

      Heads are the biggest cork on power unless there fully ported.
       
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      • Wyrmrider

        Wyrmrider FABO Gold Member FABO Gold Member

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        • Garrett Ellison

          Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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          The stock cylinder heads will need extensive machining for anything anywhere even close to that .538 and .534 lift. The stock vale retainer to guide clearance may be good for all of .460 lift on a good day... And besides that, if the bottom end is stock with around a 9.0:1 compression and you're committed to the 302 heads, no good will come out of a cam anywhere near that large. I probably would be shooting for 10.5:1 compression with that particular cam. Care to tell us what it's going in?
           
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          • RustyRatRod

            RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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            GO 3.91 on the gears and it'll be dead on.
             
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            • 72bluNblu

              72bluNblu FABO Gold Member FABO Gold Member

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              Guys, it’s a hydraulic roller. That’s a 1,800-5,800 cam. It's not crazy wild. In fact, it's the smallest Xtreme energy retrofit cam that Comp sells.

              Screen Shot 2020-06-20 at 1.42.29 AM.png

              It says it's fine for 9:1 compression. If anything the convertor the OP wants to use has too high of a stall. I think the recommended valve springs are doubles, so the heads would need to be cut for double springs but that's it. And that's not "extensive" machining.

              I wouldn't just slap it in there, it'll need the upgraded valve springs and retainers, probably rockers too. But it doesn't seem out of line at all for what the OP has.
               
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              • Garrett Ellison

                Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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                Agreed that’s not extensive machining, I was more thinking along the lines I would like to see a good valve job and some bowl and maybe a little port work to take make a little better use of that cam over the stock heads.
                 
              • YY1

                YY1 Well-Known Member

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                Advertised compression is 9.2:1 for 87.
                 
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                • nm9stheham

                  nm9stheham Well-Known Member

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                  So it will really be about 8.5! Better than the older smog engines.

                  OP, a couple of question for you:
                  • What cam is in there now?
                  • What is the goal and use for this engine? Drag race? Street cruising?
                  The cam and maybe gear choice will change depending on this. I can think of a couple of better cam choices that will do the same for peak HP and do a bit better for low end torque, if that is of interest, like the Howards .904 optimized or the Voodoo Grinds.

                  If you don't care for the low RPM torque to be better than a smogger station wagon (and indeed you may not), then the cam in the 1st post is not too big IMHO.
                   
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                  • JoJo

                    JoJo Well-Known Member

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                    I haven't done anything to the heads yet. I plan on having them ported and adding 1.88/1.60 valves. As far as the compression ratio, I think these engines are rated at 9:1 if I'm not mistaken.

                    I'm a little skeptical on the converter... I was browsing around trying to collect information and some say it would be fine and that a quality converter would be the best route. Even though my combination is mild, I don't want to hurt the performance in any way.
                     
                  • JoJo

                    JoJo Well-Known Member

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                    The factory roller cam is in it now. I want a Street/Strip setup, but nothing too wild. I do a lot of cruising and will make a few passes at the track from time to time.

                    I do care about low end torque. I'm not dedicated on buying the cam I posted. If there is a better choice for my setup, lay it on me.
                     
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                    • nm9stheham

                      nm9stheham Well-Known Member

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                      Yes on the 9:1 BUT realize that the factory published compression numbers were exaggerated. if you work the actual dimensional data, it works out that way every time. And it was not just on Mopar engines!

                      Too big of a cam will lower the low RPM torque. That is why the question on how you plan to use the engine. If you are drag racing all the time, then you don't care. The high RPM TC stall is to allow the engine to rev up on launch past the poor-torque low RPM range when a big cam is put in.

                      If you are street cruising, then low RPM torque is a big contributor to 'driveability' and good throttle response. So you change your approach there and keep the cam limited in duration and use a different cam profile to help the mid-high RPM HP with less effect on low RPM torque. Some guys like revving the car all the time, but some don't want that.

                      If you don't want to hurt the performance in any way, then I suppose that means you don't want to lose an low RPM torque, and a different a cam is a much better choice. But it would help if you stated you use and goals for the car, rather than us guessing.
                       
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                      • Garrett Ellison

                        Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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                        Those heads usually cc in at around 60 cc. I know someone who uses them for budget truck builds but gets them milled about .050 (around 56-58 cc's) along with .028 MP head gaskets for a bump in compression. He also bowl ports them and opens the intakes up to 340/360 gasket size. 1.88/1.60s are good, some of our people in the know here like a 1.94 intake in a 318 head. If your going to use a hydraulic roller but confined to a shelf grind, I like this one fairly well.
                        Howards Cams Retrofit Hydraulic Roller Camshafts 713175-10
                        I imagine your better off with a custom hydraulic roller profile, because there are many hydraulic cams that have more lift area under the curve than most off the shelf hydraulic roller grinds. If going with a hydraulic flat tappet, I really like this grind for most street applications. I'll have to look at the cam card again but it's got a fair amount of advance ground into the intake it to help maintain cylinder pressure.
                        Howards Cams Hydraulic Flat Tappet Camshafts 711451-08
                         
                      • George Jets

                        George Jets 1967 Dart 2 Door FABO Gold Member

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                        Are your '87 Roller stock flat top pistons .040 ths down in hole, like this '91stock 318 Roller that is pictured below ? That will be good for your compression.

                        Can go with the thin Mr Gasket G1121 head gasket too, with a compressed thickness of .028 ths. That will help too.

                        20200608_201627(0).jpg
                         
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                        • JoJo

                          JoJo Well-Known Member

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                          The purpose of this setup is for street cruising... Daily driven occasionally and riding out-of-town on the weekends. I Love the lower RPM torque, but it seems to fall on its face in the mid-high RPM range.
                           
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                          • George Jets

                            George Jets 1967 Dart 2 Door FABO Gold Member

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                            Not a bad setup what you have going there for street cruising. Did you do any port matching with your Weiand Action+Plus intake and opening up the 302 head ports to match the 318 intake gaskets.

                            This can eliminate turbulence getting the flow into the heads. The 302s have a pretty sharp edge right there where the port enters the heads.

                            We have had good luck with the stock 302 heads and stock valves, then you don't loose your hardened seats by putting bigger valves in them. But the big thing is to port match the intake to the heads.

                            There is this thing with the 318s called smooth port flow with the stock setups that makes an existing layout work nice.

                            We use the Edelbrock 1406 carbs with these setups, works nice. If people want to make over 300 hp, then you need to go another route. But for basic driving and cruising it is just fine.

                            318 302s before port match.
                            20200614_111858.jpg

                            318 302s after port match.
                            20200614_194409.jpg
                             
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                            • Garrett Ellison

                              Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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                              I would do the aforementioned head work and us the Howard's hydraulic roller cam. If you have the hood clearance, switch to an Edelbrock Performer RPM or Air-Gap RPM. There are two other lower cost options I like but the the Performer RPM will be worth some top end over the Action+ and probably produce a little more on the lower end, too.
                               
                            • Wyrmrider

                              Wyrmrider FABO Gold Member FABO Gold Member

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                              figure out your compression
                              you can use a harbor freight bore scope to see the piston
                              post up your current cranking compression
                              how's your timing chain?
                              you could retard your current cam 8 degrees and see how you like the torque :)

                              rockers plus a b3 kit + pushods will kill a budget
                              then fill out that cam request form
                               
                              Last edited: Jun 20, 2020
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                              • JoJo

                                JoJo Well-Known Member

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                                Yes, they sit down in the hole just like that.
                                 
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                                • JoJo

                                  JoJo Well-Known Member

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                                  Would I need to mill the intake side as well?
                                   
                                • PRH

                                  PRH Well-Known Member

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                                  The 268 would be a better fit imo.
                                   
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                                  • rumblefish360

                                    rumblefish360 So close, yet so far away FABO Gold Member

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                                    @JoJo

                                    I run that cam in the wife’s 360. I have the compression a hair under 11-1. The rest....750 carb, Weiand Stealth, OOTB Edelbrock heads, TTI “X” piped exhaust, 3.55’s on 26” tires. The trans is a 904 with a custom converter by Pro Torque (since they used to be down the block from me.) Which stalls at 2400.

                                    I feel your compression is a bit low though it need not be high like mine, your converter is way to much and could use a cam with a intake duration as high as 240@050, though that’s pushing it.

                                    If you want to run that cam, (the 274) mill the heads down
                                    (and yes, probably the intake as well, but check fit first!)
                                    Any stock head will have to be fully ported
                                    (since that move will fit your description of what you want from the car and avoid it falling on its face at mid and high rpm.)
                                    and at there cost vs what they will flow afterwards, IMO, your going to be a head of the game if you go with a set of Edelbrock’s heads instead.
                                     
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                                    • 273

                                      273 Well-Known Member

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                                      Is this a rebuild ?

                                      IF so I wouldn’t be using stock low cr pistons.

                                      For the money it would cost to do the 302 heads probably could with aftermarket.

                                      Since this seems to be mainly a street driving car I’d go a step down in cam eg. 218 @ .050”.500” . Unless you go with a lot better head.
                                       
                                    • rumblefish360

                                      rumblefish360 So close, yet so far away FABO Gold Member

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                                      I don’t think is a rebuild since the piston in use mentioned above was stock pistons.

                                      If it were a rebuild, I’d use a KB @ 0 deck height for a good ratio and it’s deep valve pockets so I could use a 1.6 ratio rocker and use that Edelbrock port flow to my advantage. A little more top end pop!

                                       
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                                      • 273

                                        273 Well-Known Member

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                                        If this ain’t a rebuild your going the expensive way to make the hp of a stock magnum engine,
                                        Just get a running 5.2l or 5.9l add 4 bbl for 300 hp add headers for 320 hp add mild cam for 360 hp more aggressive cam for 400 hp.
                                         
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