What to tell the machine shop

Slant 6 Engines

  1. cchrishefish

    cchrishefish Well-Known Member

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    I have talked to 3 different machine shops in the area, and I am being quoted $850 labor plus parts. Since my knowledge of valve lengths, cams etc is limited, I am not able to answer all of the machine shops questions.

    So here is where I am at. I want to have a 1968-74 head machined to accept larger valves, springs, some porting, milling, and change over to street performance cam.

    My engine is a stock build with 2000 miles on it, and I do not want to take the head off, so I can drive it until I have everything to perform the job.

    I do not want to have any clearance issue, or notch pistons, etc.

    Should I buy a complete kit with valves, cam, pushrods, etc, with a known combo that does not require any guesswork? The shop is asking me if I need to use a different size pushrod.

    Or, is it just a bad idea to have the head done ahead of time?

    This is a slant 6
     
    Last edited by a moderator: Feb 26, 2020
  2. jimjimjimmy

    jimjimjimmy lobsterman FABO Gold Member

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    search around for new aluminum heads might find some loaded ones for the same money .
     
  3. xLURKxDOGx

    xLURKxDOGx "An angel fat, at satan's feast" FABO Gold Member

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    Slant six.

    Jake
     
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    • jimjimjimmy

      jimjimjimmy lobsterman FABO Gold Member

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      thanks i never noticed that . sorry to the op .
       
    • Plymouth 65

      Plymouth 65 Floorable Deplorable

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      STOP! By the time you upgrade those cast iron heads you could purchase a new set of aluminium heads. Remember that an engine works as a system. Compression ratio, cam, intake/carb size, head flow, etc. I would recommend you read how to build a small block Mopar to educate yourself! 65'
       
    • Hyper_pak

      Hyper_pak Old School Chrysler Fan

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      If it was only that easy.....

      Can you explain what level of performance you are looking for?
      If you are just looking for a small performance upgrade, you do not need bigger valves, porting, oversized push rods, etc. Just a set of Rock Auto 340 replacement springs and you will be good to go. You could even shave your head 50-100 thousands and have clearance on a stock 225. You should have adjustment clearance with stock push rods.
      If you are looking for the 13's or faster you will need a serious game plan.
      Have you talked with Oregon Cams? They have quite a few slant grinds that have worked well and they can regrind your cam and lifters also. That might be the answer for your machine shop on how to set up the head.
      Plan twice, spend once!
       
    • Hyper_pak

      Hyper_pak Old School Chrysler Fan

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      SLANT SIX!!!!!!!!!!!!!!!!! Only one head and NO Aluminum options!!!!!!!!!!!!!!!
       
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      • my68barracuda

        my68barracuda Well-Known Member

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        one of the best things about building a slant is, unlike a V8, you really need to put parts together, you can’t just go catalogue shopping for a complete assembly.
        My recommendations are:
        1) get a really good handle on what you want concerning performance, octane level of the gas you want to use, how much you want to spend.
        2) invest some time here at FABO and at slant six.org many folks have posted their slant six build combos.
        3) know what you want before talking to a machine shop. Many shops are good, but you will get what they think you want, which may or may not be on target. The MS can be trusted to tell you how much the crank pins and journals need to be cut, how much the bores need to be opened to clean them up,,, but the target compression ratio, camshaft, what the cam gets degreed to when installed should be your call. Piston ring gaps should be what the piston manufacturer recommends.
        If you spec out a motor and it does not do exacty what you want, you have still learned something. Let someone else make all the decisions and all you have is a motor.
        4) one your basic questions like
        Valves: Hughes Performance has drop in OS slant valves, although others have ran compatible Ford or Chevy valves, the F and C valves take a bit more set up as they have longer stems than the stock slant valve.
        Pushrods are probably one of the last items to order, after the cam is installed and the head is done so you can measure to determine what length pushrod is needed and order the correct length.
        So invest some time on a couple slant six forums, to get yourself familiar with the possibility’s and what is available in the aftermarket for slants, then figure out what you want.
         
        Last edited: Feb 25, 2020
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        • diymirage

          diymirage HP@idle > hondaHP@redline

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          tell em to shave the head far enough to get a decent bump in compression
           
        • Demonic

          Demonic Well-Known Member

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          Anytime you build or modify an engine, you have to do some measuring as you assemble. Clay checking the valve to piston clearance, spring installed height, rocker arm contact, etc. Do not overlook this. Read up on it, V8 stuff still applies to six builds. Shouldn't be a problem getting the head done first though. Just have a plan. If you're changing the cam, you will likely need different pushrods, usually one of the last things as head gasket, head milling all affect the length.
           
        • Marcohotrod

          Marcohotrod Well-Known Member

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          a good engine shop should be able to work with you, not expect you to have all the answers. tell them to do some basic porting, see available valve sizes with the correct length, pick a cam for valve spring selection
           
        • RustyRatRod

          RustyRatRod Weenie idiot loser. FABO Gold Member

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          Find a core head to have rebuilt. That way you can spend a Saturday afternoon swapping it out. Much faster.
           
        • cchrishefish

          cchrishefish Well-Known Member

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          Yes, I have a 68-74 spare head. And, from everything I read, there is not an aluminum head on the market, correct me if I am wrong.
           
        • RustyRatRod

          RustyRatRod Weenie idiot loser. FABO Gold Member

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          I wish I could correct you. You are not wrong.
           
        • cchrishefish

          cchrishefish Well-Known Member

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          What I am after is a street performance car that will run on premium gas. I do not intend on racing, but I would like to have a fun peppy car which could also be driven on the highway if necessary. I believe a car that could do 15 second quarter miles would be about right for the street. Maybe a rear end ratio of 3:55 or 3:76, and a stall speed of maybe 2500-2600, 255 60 15 inch tires, if they will fit on a 64 Dart GT.
           
        • my68barracuda

          my68barracuda Well-Known Member

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          Since you say the bottom end is in good shape, it would make good sense to focus on the cylinder head.
          The stock style Hughes valves and 340 valve springs, pay for good multi angle valve seat work would be a start.
          Shave the head to get the compression up into the low nines, that is a bit conservative, but you say you are not a tuner..
          cc your heads use the formula .0069 to 1cc ,measure the existing piston recession and with an on line compression calculator you will know exactly what to tell the MS to mill off the head.
          Talk to Oregon Cams, tell them what you want for performance and the specifics the engine, Tom will recommend a cam.
          What are your plans for an intake-exhaust-ignition ?

          here is a good online compression calculator
          RSR Static Compression Ratio Calculator

          and here is a video on how to cc a cylinder head,


          for a stock Fel Pro gasket use .042 for the compressed thickness

          and here is link to a Tractor Supply $6.99 60cc syringe that will be plenty accurate.
          https://www.tractorsupply.com/tsc/p...h-catheter-tip?solr=1&cm_vc=-10005&st=syringe
           
          Last edited: Feb 25, 2020
        • 69_340_GTS

          69_340_GTS Well-Known Member

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          He has a slant 6!
           
        • cchrishefish

          cchrishefish Well-Known Member

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          So, I am starting to gather a few things, I am considering two different intake manifolds, the Clifford and the Aussiespeed. I like the Clifford because it has the pre heater built in. But, a pre heater can be added to the Aussiespeed manifold. So, which one do you like better and why?
          https://cliffordperformance.net/store?olsPage=products/6-equals-8-mopar-225-intake-manifold

          Slant 6 Short runner performance 4 barrel intake manifold 2 piece AS0199/AS0212 | Aussiespeed Street & Racing Products Australia
           
        • my68barracuda

          my68barracuda Well-Known Member

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          I run a Clifford with MPFI. I have a MS3 Pro ecu to run the FI.That intake had nitrous bosses, I drilled those for the injector bosses. At one point in time I had a AussieSpeed Hurricane intake. I sold it without ever running it and went with a Clifford. The Aussiespeed has the long runners that can add torque at certain RPM, and with MPFI I was not concerned about pre heat or fuel distributor. I do have a plan of adding a supercharge at some point in time, so that eliminated any need for a long runner manifold. I am familiar with water heat to provide an intake hot spot. It is worthwhile for carburetor applications.
          For an intake, I believe that either would be a fine choice. The installation and running a throttle linkage will be easier on the Clifford. The AS will have more of a wow factor.
           
          Last edited: Feb 26, 2020
        • cchrishefish

          cchrishefish Well-Known Member

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          I am leaning towards the Dutra Duals, and they should have a really good fit with the Aussispeed, has anyone fitted the Dutra Duals to the Clifford intake?
           
        • my68barracuda

          my68barracuda Well-Known Member

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          I have long tube Hookers matched to the Clifford, have Dual Dutras on a slant in the 83 D150 matched to a cast aluminum Mopar Performance 2 BBL intake. The Dual Dutras were purchased and installed about 2010, so maybe some things have changed, but I had to grind down the manufacturing lugs on the block and add clearance to the manifolds for socket clearance. Nothing major, just trial fit the manifolds to the head with no block and to the head on the block with no intake so you can get a good look.
           
        • bcschief

          bcschief Well-Known Member

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          • Agree Agree x 1
          • vitamindart

            vitamindart Well-Known Member

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            the short runner Aussie should be about the same as the Clifford, I have the Aussie Hurricane ( really long runners ). have been considering swapping it for a shorter
            runner since I plan on adding boost at some point.
             
          • 69a100

            69a100 Well-Known Member

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            I can see that the reading comprehension is equivalent to the mentality and IQ of all you A body members! The only aluminum head you will find is from the very early /6 years, and good luck finding one. Let alone how ass raped you'll get at the cost when you do find one. Good Luck
             
            • Disagree Disagree x 2
            • diymirage

              diymirage HP@idle > hondaHP@redline

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              why not get two aluminum heads?

              and the find a 5.9 magnum to bolt to the bottom of them

              poke.gif
               
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