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  •  » FYI Ford, Classic Mustang Tech Discussion
  •  » 347 build.

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    6/04/2023 2:20 PM  #1

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
    Posts: 12,220

    347 build.

    Does a 347 require clearancing of the block’s pan rail area for rod clearance?  Bottom of cylinders?
    Or, does it just bolt in without mods?

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    6/04/2023 4:22 PM  #2

    6sally6
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    From: Surfside Beach,SC
    Registered: 4/02/2013
    Posts: 6,820

    Re: 347 build.

    Never built one butt.........I think 'some' stroker kits have different cap screws so they will clear.
    Take lottsa pitcherz !!!
    6sal6

    Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
     

    6/04/2023 8:54 PM  #3

    Quicksilver
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    From: California Central Coast
    Registered: 9/22/2013
    Posts: 264

    Re: 347 build.

    MS, found this....Rod bolt to cylinder was the only place I had to grind. It calls for a minimum .060" clearance. Think mine ended up being more like .200".Didn't take long with a die grinder and a couple stones. Mock up a piston/rod/bearing (no rings) for each bank. Bolt to the crank and slowly turn it over. Mark the cylinder with paint where you need to grind.

    Money can't buy happiness. Butt it can buy Car Parts... and that is pretty much the same thing.67 FastBack
     

    6/04/2023 9:03 PM  #4

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
    Posts: 12,220

    Re: 347 build.

    I took another one of my 5.0 explorer engines apart today. It was a 1998 model.  Only difference in the short block. Between it and the 97 was the 98 had plastic gizmos instead of the HO style dogbones to keep the lifters aligned.

    This engine was in better condition than the 97 GT40 engine I took apart the other day!  Both near perfect.

    I have one more HO 5.0 to take apart.  Once that is done, all the dirty work will be completed.  I know the next one has a bad crank. Once I get all of them apart, I have to decide what to build out of the four blocks.  So far, only one has had any scoring because some bozo let the oil control ring pop out of the ring land when they assembled it.  The other three are virgin blocks. Never been apart from new.

    I soaked all the pistons in Purple Power solution for two days. The crud on them wiped right off leaving what looks like a brand new piston. Love that Purple Power!

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
       •Thread Starter
     

    6/05/2023 7:43 AM  #5

    TKOPerformance
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    From: Newark, DE
    Registered: 12/15/2014
    Posts: 7,466

    Re: 347 build.

    Both my 347 and 331 required clearance grinding.  Most machine shops have a template or just know where to grind.  Two different shops did the machine work on those engines and both had no clearance issues on assembly. 

     

    6/05/2023 8:36 AM  #6

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
    Posts: 12,220

    Re: 347 build.

    My 331 in my 69 has a 331 and did not require any clearancing.  I guess it depends on the rods and bolts?

    I have pretty much, for now, decided a stock flat top Explorer short block will be perfectly fine for my use.  I will spend the bucks to upgrade the cam, keeping it small and with reasonably smooth idle.

    Looking at two hydraulic rollers
    268/272  .512 lift. 114 degree LC
    Ford Alpha cam with .498 lift

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
       •Thread Starter
     

    6/05/2023 9:48 AM  #7

    TKOPerformance
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    From: Newark, DE
    Registered: 12/15/2014
    Posts: 7,466

    Re: 347 build.

    I believe the issue is either the capscrew rod bolts or increased size of aftermarket rods (or both).  IIRC the 331 had a lot of clearance, like way more that would be absolutely necessary to clear, but I suppose the thoughts were better safe than sorry.  In fairness, I did not mock up either engine before final assembly and simply, went with the advice of the machine shop, one of which does a lot of SBFs.  So possibly one or both would have cleared witho9ut grinding, but I trusted in those who build engines every day and can only say definitively it wasn't an issue with the machining that was done. 

    My question would be what heads do you plan to use?  If you are keeping the GT40 or GT40P heads I think you are probably better off with a 302-306 build anyway.  With a decent cam it should easily make 350 HP.  Light car and manual trans with a decent rear gear and it'll be plenty of fun to drive.  Only thing to remember is the P heads in particular have some spring, valve rotator stuff going on that create issues with high lift cams.  Its cheap enough to remedy, but must be addressed once you are much over stock lift. 
     

     

    6/05/2023 4:47 PM  #8

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
    Posts: 12,220

    Re: 347 build.

    Gt40 3-bar heads with new springs to match my cam and proper retainers.
    I decided to use either the stock flat top cast pistons or a new set of hypereutectic flat tops 4.030” I have on the shelf, and spend a little getting a new cam. The pistons have larger valve reliefs and will lower compression, but maybe the 0.030” overbore will add a little back. Depends on if the block I am having bore cleans ip at 0.030” or 0.040”.

    I have a new set of 0.040” dished pistons already hung on a set of rods and can use those with a set of E7 heads to make a decent 289 replacement for somebody.

    My other three blocks are all low mile standard bore and I hate to bore them out for no reason.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
       •Thread Starter
     

     

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