906 heads, 280 cfm @ .500" lift

General Mopar Tech Discussions

  1. IQ52

    IQ52 Well-Known Member

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    The 906 intake port. Sometimes you make something pretty and nobody ever calls you back to say how it runs. I think these were supposed to go on a '70 Road Runner. The 906 up against the best OOTB RPM I ever tested. The RPM flows are from 5 or 6 years ago and flowed very near their advertised specs. The later ones I've tested have dropped off some.

    Lift.................OOTB RPM IN/EX..............Ported 906 IN/EX

    .100......................73/70..............................80/61
    .200....................148/126...........................161/126
    .300....................209/160...........................219/175
    .400....................254/188...........................262/201
    .500....................276/206...........................280/215
    .600....................287/217...........................297/221
    .700....................291/223...........................297/224

    George Tuttle 906 004.jpg
     
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    • lewtot184

      lewtot184 Well-Known Member

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      i'm not impressed with the rpm's i'm currently running. but, i had some decent iron heads before the switch. i think this alum head thing is like tatoo's,...everybody thinks they need one.
       
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      • cdr

        cdr FBBO Gold Member FBBO Gold Member

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        very pretty!!! my port work don't look as sexxy
        [​IMG]
         
      • KENTON

        KENTON Well-Known Member

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        They look real nice & have some great flow #s. I'm going to have to get over that way sometime. I need to bring you a set of 906s and some other work too.
         
      • MoparMitch

        MoparMitch FBBO Gold Member FBBO Gold Member

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        Can you send those to me ???
         
      • Cranky

        Cranky Henchman #27 Staff Member FBBO Gold Member

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        The RPM's have raised ports, closed chambers and angled plugs vs the 906. Even if the 906 flowed the same, wouldn't the RPM's still perform better? I've run some 10.50's with a set of max ported 906's but have never run the Eddy's with the same combination but have seen some others that ran faster with similar combinations in like weight cars....
         
      • lewtot184

        lewtot184 Well-Known Member

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        the rpms don't have raised ports. everything is in the stock location. the indy sr's have a raised intake and exhaust port. ez's have a raised intake and stock location exhaust port. all this alum head stuff boils down to the fact that they are no better than the old stuff is bad. the real value of alum heads is repairability. if there were an iron head with all the port mods and equal valve sizes they would make more power than alum. the alum weight thing isn't even a good argument. if you consider total head weight loss vs total car weight and weight distribution it doesn't mean much. i'm going back to iron.
         
      • Cranky

        Cranky Henchman #27 Staff Member FBBO Gold Member

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        Well, that's funny, I have a set here that measure around .100" higher on the exhaust port exit. Even the bolts holes are higher than the cast iron heads. Don't know if the 60189 are basically the same external dimensions as the 60929 but the ones I have sitting here are the 929's.....
         
      • lewtot184

        lewtot184 Well-Known Member

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        the exhaust ports on the rpm's i have are in the same location as the iron heads i took off. if the intake ports were raised then the manifold flange would have to be extended out to compensate for the height and a spacer would be needed at the block end rails to raise the valley pan. i've messed with raised port heads before and the edlbrock rpm's aren't. look at how the extended intake manifold flange on the victor's are, raised ports. indy's even have an extended intake flange. stage 6's are raised ports, intake and exhaust, but need a spacer to be used on rb blocks.
         
      • mopar 3 B

        mopar 3 B Well-Known Member

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        The only real advantage aluminum should have would be heat displacement and it affect on fuel. All other factors can be fabricated equal cast or aluminum
         
      • themechanic

        themechanic Oklahoma is OK FBBO Gold Member

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        What's the cost of porting and polishing and new parts for 906 heads versus all new OOTB aluminum heads? In other words, which path gives ore bang for the buck?
         
      • 67Satty

        67Satty Well-Known Member

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        You can buy some of the "Sidewinder" RPM copy aluminum heads ready to bolt on with good springs and retainers and a good valve job that flow a little better than OOTB RPMs for about $1100.

        I was quoted about the same price by a local guy to do up a set of 906s ready to bolt on that flow about the same. I'm guessing that IQ52 would want more than $1100 for his 906s ready to bolt on?

        So for the same price and flow would you want the 50 pounds less off the front end and the close-chambered head giving you quench that he aluminum heads offer?
         
      • rumblefish360

        rumblefish360 Well-Known Member

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        The quench offered by the closed chambered Edelbrock heads only comes into effect if the piston can be, in an example, at zero deck with a gasket not exceeding .050.
        So a piston swap is in order.

        To use any quenching possibility with an open chambered iron head, some slugs need to be employed.
         
      • IQ52

        IQ52 Well-Known Member

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        Anytime. Be glad to have you visit again.

        Not those, they better be on the Road Runner. How many do you want? Send good cores and money.
         
      • Cranky

        Cranky Henchman #27 Staff Member FBBO Gold Member

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        The intake entry on the Eddys is in the same location as the stock heads but the port floor on the stockers are pretty flat at the entrance and the Eddys are not that way. Don't know why you're having problems with them. There's at least one member on this site that has run high 9's with em.....but I don't know his combo or car weight.

        The biggest problem with max ported 906's is that they are prone to cracking. They are a production passenger car head that works pretty well for high performance use but they are not an all out drag racing head. It's been years since I paid anyone to do any port work so I can't really answer that question but the last time I had a set of small heads pocket ported, it was 200 bucks but that was in the mid 90's. But, if you do no other port work, doing the valve pockets is the best bang for the buck imo as the factory back cut pretty much sucks as produced.
         
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        • IQ52

          IQ52 Well-Known Member

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          I wish the answer was as simple as the question.

          There is so much information that needs to go along with the dollar question. It's like trying to explain to your teenage daughter why the guy she is so "in love with" is really a dirt bag. Where do you start so there will be some comprehension?

          To most of us it is just this cylinder head is $150 cheaper than this other one, or this boy has less pimples and his hair is more "dreamy" that Fred's.

          You set the head up for the engine design.

          Intake flows for three 906 heads, same 2.14 intake valve. And a service prepped RPM

          .100...........89..........80..........71....................................75
          .200..........168........161........150..................................150
          .300..........218........219........209..................................211
          .400..........249........262........257..................................254
          .500..........260........280........292..................................285
          .600..........258........297........313..................................295
          .700..........258........297........321..................................297

          The first two will cost less ($1,450/$1,950 + cores) than a pair of service prepped RPM heads ($2,120). And the iron heads will come with better springs, retainers and locks.

          Sometimes you just gamble and install OOTB RPM and Stealth heads for $1,620 and $1,000

          - - - Updated - - -

          I hear the 906 heads are prone to cracking. We had one exhaust port crack and we knew we had screwed that one up. Yet we've had 906 heads making 750HP normally aspirated on 91 octane, run on Comp Cams dyno without water, and still when the water was turned back on there were no cracks. Again.......you must be smarter than your cylinder heads when you port them.
           
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          • Cranky

            Cranky Henchman #27 Staff Member FBBO Gold Member

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            Yup...had over 300 passes running 7300 through the traps running mid 10's on my junk and no cracks. I think starting with good cores is one of the things that help with keeping the cracks at bay. I forgot to turn on my water pump on a pass and didn't notice the temp was up pretty good and then flipped it on thinking here we go, hitting the heads with cold water but they made it. The temp sure came down in a hurry too lol
             
          • lewtot184

            lewtot184 Well-Known Member

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            rocker geometry was awful, casting quality was crap, ain't worth 1600 bucks.
             
          • Budnicks

            Budnicks You Can Just Thank Me Later FBBO Gold Member

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            I'm not sure why there's this negative stuff about the Edelbrock RPM heads,
            yes there is probably certainly better aluminum "racing heads" out there,
            depends on what you need & possibly a bad casting here & there maybe too,
            really depends on what your end goal is, what your experiences actually are,
            but for "bang for the buck", middle of the road price range,
            IMO the RPM's are pretty damn good... I've had nothing but good luck...
            I haven't heard very many negative complaints about them,
            especially when it came to the castings quality...
            But that's just in my little world, others may have had different experiences...

            I had tried the Alum. Stealth heads that were professionally ported,
            by the same guy {Mark Lowe},
            that barely could break the 10.00 barrier,
            mid 9.90's only about a 1/10th better than my Iron heads,
            most of that was because of weight saving over the iron heads only...
            By the way it took allot more port work, parts were inferior to the Eddy's also,
            just to make them "as good"
            {slightly better after allot of porting & parts changes}
            as the Eddy RPM's were stock/std OOTB/Flow rates...

            anyway back on subject at hand the RPM's

            I don't have dyno #'s, I rarely ever dyno-ed any of my combos...
            I have real world track #'s mostly on a 90*+ to 100* days
            at a couple of test & tune days at Sacramento Raceway,
            that car in this thread was only equipped with a 4pt roll bar &
            frame connectors & added torque boxes,
            couldn't really run it in races it was too fast for the safety equipment it had,
            I wasn't willing or maybe too stubborn to back off either,
            it was really merely my street/strip car/toy, not my racecar... Anyway

            In my opinion, the Eddy RPM's in either open 88cc or closed 84cc,
            if they were properly set up, checked & cleaned up,
            {I don't & wont run anyone's heads right Out of the Box}
            I would change to the proper springs, retainers, locks,
            to match your needs & camshaft etc. {if necessary}
            IMO they are a great choice, for middle of the road type builds,
            many engine builders will say the same thing too...


            Now please don't quote me this is going off my memory,
            not meant to deceive anyone if a few facts were off,
            inadvertent & not intended as such...

            Just the near 70#'s in weight saving alone, will improve performance,
            less weight on the front end, less wear on brakes & shocks,
            better cooling/heat dissipation {albeit marginal},
            but cool down times were far quicker, less heat soak, same everything else,
            I went from running @ 190*-200*- high of 210* {with Iron heads},
            to never really over 190* ever with the new alum. heads

            The RPM's better flame travel & more complete burn with angle plugs
            & heart shaped combustion chamber designs
            {some certain cheaper brands header clearance issues},
            the RPMs have stock intake, exhaust port & rocker shaft locations,
            but improved port design {see IQ52's many posts} over the factory 906
            & other OE Iron heads...

            There's nothing wrong with the heavy OE Iron 906 heads,
            if ported "properly", but stock there's no comparison,
            even to the OOTB Eddy RPMS,
            unless they {the 906's} are ported they are still heavy & 40 years old
            {they can be made to be pretty damn good}
            & the Eddy heads can be made to flow allot more than what they are OOTB...
            Some 40+cfm in my case, more in some other cases

            I had a set of very good 906's fully & professionally ported buy Mark Lowe
            {may he rest in peace}
            IIRC they flowed in the 315cfm range, 3520# 68 RR 479ci/6bbl
            ran low 10.00's best passes, thru the mufflers, we tried for comparison sake,
            some of the then relatively new at the time alum. Eddy 929 84cc heads...
            I had tried the Stealths & had issues {wont go into that here}
            basically the RPM's Out of the Box flow #'s & 2.14 & 1.81 valves,
            might have been 10-12cfm better flow than OOTB #'s
            by a little cleaning up in the pockets, short side radius clean up, there was
            a slight lip under the valves in the pockets, where it was machined/cut from the factory
            & we went to a 50* back cut on the valve job IIRC {this was about 10 years ago now}
            we just changed the valve springs, retainers, locks & added lash caps
            & Smith bros. 3/8" & proper length pushrods
            {on the Stealth's you need to grind a bunch in the push rod passage area outside &
            next to the intake ports, if you use 1.6:1 rocker &/or 3/8" push rods}
            ,
            {different set up than the pushrods that were on the 906's too, differ length}
            & my 1.6:1 Crane Super Gold rollers, that were used on all my heads,
            I just changed stuff to match my camshaft & for proper rocker geometry...

            The car 60ft went from 1.33 to 1.29 IIRC, front end lift/weight transfer,
            was far better too,
            the 330ft times were where it really was better,
            made up most all the improvement in my et, in the 1st 660ft,
            the head design was way better in the low to upper midrange, from 3500-5500
            partially because of better spark, intake & exhausts port floor design
            {that's what Mark Said & I saw anyway}
            the et went from 10.0's {10.02 -10.04's} @ 129 best
            {about 127mph average normally},
            to 9.77 @ a best of 135mph best
            after a jet change had to go up 6 jet sizes,
            larger squirters #31's IIRC & the pink accel. pump cam with 50cc accel. pump
            on the center carb,
            she was really wanting more allot more fuel with the RPM's at the hit & down low
            WO throttle it was OK {had {Promaxx adj. jets in the outboards},
            with the only other change, was the cleaned up Eddy 929 heads & valve springs etc...
            The car hit the tire way harder,
            had to do some CalTracs, shock adj. & air pressure adj. too,
            partially because of the weight taken off the front of the car...

            It had even more in it, but didn't want to veer to far, from the comparison,
            it needed a gear change {less gear ratio}
            & converter change eventually {more converter},
            but I was running decent & was going to be testing N20 after that point
            & the comparison were way different...

            Using the RPM's, way better than the iron-heads,
            hands down night & day better...
            I went the best of 8.58 @ 156mph with a single dominator & 300 shot, but that's
            a whole other ball game, not the best way to compare parts,
            unless the same parts were used with the same tune up etc.,
            I sold the car not very long after that,
            I have a very similar build now today too, less cam & less port work etc.
            very happy with the parts choices, even if some are kind of outdated now...

            That's a real world experience,
            I did a similar comparison when I did the Stealth heads too,
            I didn't have anywhere near as good of results,
            But the new Stealth's are better than the original design too...
            Much like a copy of the Iron 906's except Alum. & in many ways, even OOTB flow rates...
            But IMO still nothing like the RPM's, but the Stealth's also have straight plugs
            & look allot more like OE style cast iron heads when they're painted,
            if that's a necessity...

            sorry for the rambling, I'd suggest listening to IQ52 he's the cylinder-head expert
            anything he says is like gold or gospel in my mind,
            not very many people, a very select few, I would say that about
            {my buddy departed friend/professional head porter, Mark Lowe was also one of them also}

            doesn't mean the OE style 906 Iron heads are bad "at all"
            it's just not what my personal choice would be or
            what I'd run in a performance application,
            especially if it's properly set up...

            That's what great, different people have different likes & preferences,
            even different experiences...
            The world would be boring as hell, if we all liked the same thing,
            if we all built the same things...
            I love all the new tech, all the better parts & welcome change with open eyes,
            some have been great experiences & some not so much...

            To each their own, I'm not saying my stuff or my opinion is any better,
            or that someone else's opinions & experiences are wrong,
            it's just what I have done & had success with...

            It's far more than just the engine or just which heads,
            it's about the whole combo, how everything works together...
            that's my $0.02 cents
             
            Last edited: Mar 15, 2015
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            • KENTON

              KENTON Well-Known Member

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              While were on the subject, do the 4120437 templates work on 906 heads? Im not thinking of drag racing, just doing a nice 69 Runner with matching #s stuff.
               
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