Manifold fitment question

Small Block Mopar Engine

  1. scott657

    scott657 Well-Known Member

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    Will 360 heads milled .040 create an intake manifold fitment issue.
    As always thanks for the knowledge
     
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    • 66fs

      66fs Well-Known Member

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      I always mill the intake side of the head .038. Never a problem.
       
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      • stixx

        stixx FABO Gold Member FABO Gold Member

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        FABO member 360willrun supposedly has done this more than one time without milling the intake.
        He will chime in..
         
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        • 4spdragtop

          4spdragtop FABO Gold Member FABO Gold Member

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          No offense to anyone here, BUT if you are getting them machined, a machinist is involved.....ask them. Or put 100% faith in the internet.
          I asked my machinist the same question..I cant remember the answer lol.
           
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          • oldkimmer

            oldkimmer FABO Gold Member FABO Gold Member

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            U could also have them angle milled. Kim
             
          • 69_340_GTS

            69_340_GTS Well-Known Member

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            When you mill the head (head gasket side) you also should mill the intake side of the head about 95%. So, .040 off head gasket side, take .038 off intake side. IMHO .040 likely will cause the intake manifold to not fit right. You could have trouble getting all/some of the bolts in. Sometimes elongating the holes in the intake will help. As for leaks (air, water, oil) sometimes these can be "fixed" with thick gaskets or RTV, but it's much easier to do it right the 1st time!
             
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            • JBurch

              JBurch Well-Known Member

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              As others have already stated; maybe, maybe not, though if it were me, I would do the compensation cut on the intake, if the chamber side was cut .040.

              If you were to angle mill the heads.....alot of work, but you can get a real tight chamber and compression boost.....I would say you must check piston to valve clearance, and most likely you will be having new eye brows cut into the crown for clearance.
               
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              • Garrett Ellison

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

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                Yes, just get the intake flange of the heads milled the corresponding 95%. I’ve done a lot of reading and asked more than a few questions on here about how to do different head combinations. The common answer with angle milling is that a small block Mopar valves already open on the cylinder bore center and angle milling moves them of the center axis. With other engines, the angle milling moves the valves closer to center. So in the case of the SBM, the gains in combustion chamber efficiency are offset from the flow loss from moving the valves off bore center. Along those same lines, I had read some older literature were Bob Mullen and crew worked on a set of W2 heads for a big block after developing the small block heads. It turned out because the valves don’t open on center in the big block, the W2 port which was designed and perfected for the small block architecture, could do no better in the big block than the 906 or 452 style ports.
                 
              • scott657

                scott657 Well-Known Member

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                Thanks for all the replies
                 
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                • AJ/FormS

                  AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

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                  The more parts machining you do, the more things can go wrong.
                  With deck milling, IMO, the trickiest to get right.
                  If I get involved in another build, I'll get me some custom pistons before I do any deck work. And that goes double for line-hones.
                   
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                  • toolmanmike

                    toolmanmike FABO Staff Staff Member FABO Gold Member

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                    And just remember, If you mill the heads and need to mill the intake to get it to fit, those parts should always be used together on the next engine (if there is one).. I milled the heads on my 273 and already had them bolted on when my intake didn't fit. I machined the intake instead of unbolting the heads and machining the intake surface. No worries though, the heads were 2 different numbers, I had them ported, and the intake was a CAP intake not correct for the car. I have since picked up a nice set of correct heads and intake if I need to change.
                     
                  • 69_340_GTS

                    69_340_GTS Well-Known Member

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                    That is why you never mill an intake manifold! Always do both sides of the heads.
                     
                  • yellow rose

                    yellow rose Doctor of Thinkology.

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                    The problem is you can only mill so much off the face of the head before you get into the valve cover bolts.

                    And, those heads only work with that intake and block.

                    So in the long run, it doesn't matter which you mill. Because once you start working on it, the stuff usually won't fit other things.
                     
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                    • DrEamer

                      DrEamer Well-Known Member

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                      So, a side question here, does a Magnum block with it's lower deck height, cause an issue with intake fit when using a LA intake. I assume that if it were drilled for a LA it would be fine, but thought it worth the ask.
                       
                    • scott657

                      scott657 Well-Known Member

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                      Would a thicker head gasket negate the milling(along with the compression gains? ) maybe pick up a bit of compression.
                      I’m considering buying a ser of rebuilt heads that have been milled already
                       
                    • yellow rose

                      yellow rose Doctor of Thinkology.

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                      If you mill the heads or the block or both, you'd need thinner gaskets. You can only get down to a .030 gasket, if you are lucky. Maybe only .045 if you are sort of lucky.

                      As you mill the heads or block or both, you make the heads closer together. So you either have to mill the face of the head or the intake manifold.

                      Either way, it's most likely it won't fit any other combination again.
                       
                    • scott657

                      scott657 Well-Known Member

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                      Thank you
                       
                    • 66fs

                      66fs Well-Known Member

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                      At .040 block side and .038 intake side, the heads are a matched set. Those numbers are from the Chrysler Racing Manual. I have never had a problem with factory or aluminum intakes fitting or getting close to valve cover bolts. The port roof also lines up. This holds for unmilled heads, not excessively decked blocks.
                       
                      Last edited: Jun 11, 2019
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                      • scott657

                        scott657 Well-Known Member

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                        One more question
                        Would milling the heads create a pushrod length issue
                         
                      • Bobzilla

                        Bobzilla Well-Known Member

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                        The Magnum deck height is close enough to an LA that it does not usually add enough misalignment to worry about. You still have to check it just because of all the different part tolerances, especially since you are also talking about a modified bolt pattern or an aftermarket head for the LA pattern.
                         
                      • toolmanmike

                        toolmanmike FABO Staff Staff Member FABO Gold Member

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                        Yes it can.
                         
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                        • 66fs

                          66fs Well-Known Member

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                          You can add shims under the rocker shafts, but usually .040 of an inch would be taken up by a hydraulic lifter.
                           
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