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  •  » FYI Ford, Classic Mustang Tech Discussion
  •  » What problems will I run into swapping 302 to 351w?

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    1/01/2020 2:07 PM  #1

    Cougar man
    FYI FORD Member

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    From: Grand Prairie TX
    Registered: 9/22/2019
    Posts: 18

    What problems will I run into swapping 302 to 351w?

    I have a 68 302 auto that I will be swapping in a 351 w with a T5. I know the basics of the tranny swap with shortening the driveshaft and converting the pedals(thanks steve) .
    I more want to know of the things I will need that I can not swap from the 302 or issues others may have ran into.

    thanks 
    Brian

     

    1/01/2020 6:21 PM  #2

    lowercasesteve
    Senior 24-7 FYI Addict

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    From: Auburn, Ca
    Registered: 4/01/2013
    Posts: 1,255

    Re: What problems will I run into swapping 302 to 351w?

    several things to consider.
    Some of the 351 pullies and the 302 pullies will not work together.  the added deck height makes some of the 302 pullies not work with the 351.  Try to get the 351 pullies even if they have more grooves than you need.  This is one of the more challenging items unless you get a custom set from one of the aftermarket companies.

    You can get a set of shorty 351 headers for your swap.  I prefer shorties as it is easier to tuck the tail pipes under the  car with them and there is more space under the hood.  The 351 exhaust manifolds are huge, and may not work.

    Otherwise most everything works as is.  the bell housing bolts, engine mounts, clutch/trans mechanism and such work just fine.  Later year 351's had no bung for a stock mechanical clutch mechanism.  You may have to go hydraulic or  cable release.

    Measure before you go getting a new drive shaft.  Try yours out first.  Mine worked just fine as is.  Some have to change the length.

    Other than that, the swap is pretty straight forward. 

    Last edited by lowercasesteve (1/01/2020 6:28 PM)

    Original owner - 351w,T-5, 4whl disks, power R&P
     

    1/01/2020 8:11 PM  #3

    MS
    Forum Originator

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    From: Canyon Lake, Texas
    Registered: 1/24/2013
    Posts: 12,283

    Re: What problems will I run into swapping 302 to 351w?

    The only real difference in pulley situation is with alternator and a/c mounts. If you get a 1969 alternator mount, (the part that bolts to the head) that issue is eliminated. Also need a 69 a/c compressor mount that sits lower than the 302 mount. If using sanden compressor, just get the 351 mounts for it. Use your 68 302 balancer and all pulleys will work fine.  The 302 timing cover and dipstick will work. Water pump from 302 interchanges, but use the 68-69 timing cover.

    Stock 351w exhaust manifolds will fit your 68 perfectly, as long as they are early style for Cougar or Mustang.  I also prefer the shorty headers from JBA.  New h-pipe will be required.

    Oil pan, oil pump, intake manifold and distributor are unique to 351w.

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

    1/02/2020 7:10 AM  #4

    TKOPerformance
    Hyper FYIFORD ADDICT

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    From: Newark, DE
    Registered: 12/15/2014
    Posts: 7,518

    Re: What problems will I run into swapping 302 to 351w?

    Now's a good time for a new balancer.  The rubber in them breaks down over time, and while catastrophic failure is a possibility, the real issue I've seen is timing marks moving because the outer ring rotated around the hub.  Cheap insurance IMO. 

     

    1/02/2020 1:04 PM  #5

    lowercasesteve
    Senior 24-7 FYI Addict

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    From: Auburn, Ca
    Registered: 4/01/2013
    Posts: 1,255

    Re: What problems will I run into swapping 302 to 351w?

    MS wrote:

    The only real difference in pulley situation is with alternator and a/c mounts. If you get a 1969 alternator mount, (the part that bolts to the head) that issue is eliminated. Also need a 69 a/c compressor mount that sits lower than the 302 mount. If using sanden compressor, just get the 351 mounts for it. Use your 68 302 balancer and all pulleys will work fine. The 302 timing cover and dipstick will work. Water pump from 302 interchanges, but use the 68-69 timing cover.

    Stock 351w exhaust manifolds will fit your 68 perfectly, as long as they are early style for Cougar or Mustang. I also prefer the shorty headers from JBA. New h-pipe will be required.

    Oil pan, oil pump, intake manifold and distributor are unique to 351w.

    To clarify my pully problems - When I installed the 351, I needed a single groove crank pully and I could not find any as 351's have a 4 bolt mount and 289's have a 3 bolt mount.  Now I have a dampner with both bolt patterns and can use the 289 crank pully.
     

    Original owner - 351w,T-5, 4whl disks, power R&P
     

     

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