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Technical 351w balance issues

Discussion in 'The Hokey Ass Message Board' started by 31Vicky with a hemi, Aug 26, 2016.

  1. So, first off I'm not as well versed in these ford engines as others makes.
    From reading Ive learned there are some differences.

    And it can take quite some time to find it.

    So here's the issue and obstacles.
    He purchased A "rebuilt" ready to run engine several years ago.
    A 28 once balancer and flex plate were installed & That's all the history I have with few cloudy tidbits. The '65 truck finally got finished on the road a few weeks ago and presented these issues.

    It starts great and idles well, but shakes a tiny bit. In park and neutral At 1500 rpm it vibrates horribly and doesn't stop. In gear and accelerating it vibrates to the point of giving a physical headache, at speed the vibration remains but turns to a numbing frequency.

    The engine #s are D9AE 6015 ED15. That should be '79
    However the balancer and pulleies are 3 bolt and that should be earlier than 79 I believe.
    One cloudy bit of second hand info is that the body shop guy who put the truck together found the balancer bad and replaced it with a new one, his statement was that the crank is early 70's and that's the new 28once balancer he put on. ??? Not sure how the cranks differ there but like I said I know little about fords.

    Not quite sure what to check or even how to begin.

    Attached Files:

  2. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    from BC

    Never messed with 351 windsors, and I am in Vietnam till the 3rd, so I don't have any of my manuals or parts books handy.
  3. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    from Wisconsin

  4. So I'll assume the either will fit both engines?
    And it sounds like without intimate knowledge of the crank there's no way to tell what it should have ?

    Is that correct ?

  5. squirrel
    Joined: Sep 23, 2004
    Posts: 47,944


    that's right. You need to know what crank it has. And the damper and flexplate will fit on the wrong engine, they all bolt together just fine. And don't work right. But Chevys and Mopars and AMCs all share this interchangeability "feature".

    If you can pull the pan and find the crank casting number, that might be a big help. Or assume that it's a 79 or newer crank, and try the appropriate damper and flexplate.
  6. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,164


    All 351 were 28 oz balance a 28 oz balancer the weight goes less than 1/2 way around a 50oz is more than 1/2 way. It's hard to tell on a flex plate by the weight. The part # on a Ford plate stamped on the trans side should start with a DO for a 28 oz EO for a 50 oz.
    onetrickpony likes this.
  7. What would be the difference between early and late? or how many options between them?
  8. According to summit racing application chart,
    The 28 once balancer fits all 289,302,351w with no stipulation between early or late or engine sizes. That leads me to believe it's just one and that one works for all ?
    Would that be correct ?
  9. ALL 351W are 28.2 oz balance. ALL, regardless of year. Period! (As are 351C)
    260, 289 and Early 302 (pre mid 1981) are also 28.2 oz - after mid 1981 they went to 50 oz, but only on 302/5.0 NOT the 351W.
    Firing order is the other difference. ALL 351W 1-3-7-2-6-5-4-8 (as are the later 5.0 HO roller motor)
    260-302 (non 5.0 HO) are 1-5-4-2-6-3-7-8 same as FE and 429/460
  10. Yes I hear that all are 28 ounce.
    So, my question is are all them the same, identical, and swap around without issue.?
    If the answer is yes, then I can eliminate the balancer and I'm chasing something else.
    If the answer is no, then I have some diggings to do on the differences in balancers.

    The ford #s above say there is difference but the summit application chart say that the balancer fits regardless. For all I know the difference can be bolt threads, or it can be weight placement to key location.
  11. Check the damper; while Ford used 4-bolt dampers on just about everything starting in about '68, they did continue to make the 3-bolt versions for marine motors in both balance weights (as most marine conversions used a 3-bolt pulley) to the end of production. All 351W are 28 oz motors, but some aftermarket dampers are designed for both with a add-on weight for the later 302, which may be the case for the Summit damper. It also depends on what transmission is connected to the motor; non-truck AOD trans were ONLY installed to 50 oz 302s, so a special 28 oz 'conversion' flexplate is needed.

    The one difference in the 3-bolt marine dampers is how the pulley locates; the early car dampers had a recess that a lip on the pulley fit into, the marine units have the lip on the damper, no lip on the pulley. But if it's been machined for the early pulley, you'll have to check part numbers.
  12. There are indeed balancers that have bolt on weights to work with both the 28.2 and 50 oz imbalance. These are all machined "Billet" looking balancers, no stock cast balancers are like that - They are one or the other.
    The 3 bolt / 4 bolt doesn't matter to balance - just when you go to bolt up the pulleys. And here are new balancers with Both bolt patterns
  13. I have Never seen a 50 oz 3 bolt - not even on my injected 5.0 Bayliner motor. Hmmmmmm
  14. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,164


    A 351 will take a 28oz unit here is when it gets fuzzy 302 HO are 50oz but some standard 302 stayed 28oz until 87
  15. The Summit applications show two dampers; the SUM 163289 and the SUM 163302. The only difference between them is the bolt-on balance weight. The 289 part # fits ALL 28 oz motors, the 302 is for the late 50 oz motors.

    Not many people have. I believe these were sold on 're-power' motors mostly (replacement motors for older boats), but may have been used on others depending on the 'front dress' the manufacturer used. But I had one, off a all-but-new 50 oz 302 that the boat owner had installed and then failed to winterize, cracking the block beyond repair. I used the complete rotating assembly (less the pistons) in a 289 5-bolt block. I had the damper machined for the early pulley, other than that it bolted in.
  16. I agree with Crazy Steve, check the flex plate balance!
  17. chessterd5
    Joined: May 26, 2013
    Posts: 640

    from u.s.a.

    You can try changing the firing order to that of a 302 & see if it "fixes itself". Since camshafts are interchangeable & may not know wich one you have in it to begin with since it was a "rebuilt" motor. But the only time I've seen where the camshafts had been swapped the vehicle wouldn't run "at speed" it would just bog down & die cause it was only running on 4 cylinders.
    One more possibility is you have a flexplate for a Ford 300 engine on it. They are zero balance and should bolt up just fine even though its not right for the engine.
    afaulk likes this.
  18. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,164


    If the trans is an AOD it's a good chance it's got a 50oz flexplate.
    JeffB2 likes this.
  19. It does have a 1991 AOD from a 302 mustang. However I believe this is the 28once flex plate.

    Here's the balancer , also 28 ounce

  20. fordcpe
    Joined: Nov 4, 2005
    Posts: 636


    [​IMG]Stole this from another thread on the hamb
  21. fordcpe
    Joined: Nov 4, 2005
    Posts: 636


    Your looks like a 50 to me. Just look at the big oval holes that is the 50 oz. one and yours has that. Darrell
  22. fordcpe
    Joined: Nov 4, 2005
    Posts: 636


    And you have to watch witch 28oz. early flex plate you use with aod trans I think
  23. Yep, looks like a 50 oz unit... Ford didn't make a factory 28 oz AOD flexplate, they were aftermarket only although Ford did sell one through Ford Motorsport. Look for the cutaway in the plate opposite the weight...
  25. There's the cut out.

    And there's the series of oval holes above but just before the weight.?
    Last edited: Aug 31, 2016
  26. Yep, that's a 50 oz.... bummer. Those small oval holes appear to be balance holes, must be for 'fine tuning' the balance as I see these as varying between individual flexplates. Do a tooth count, and order the right conversion flexplate from Summit or your fav mail order shop...
  27. JeffB2
    Joined: Dec 18, 2006
    Posts: 8,775

    from Phoenix,AZ

  28. I need anything but a swapped up mixed up ford in here. Someone else did this and got paid to mess it up.

    I was 4 mins into this, drove around the lot ,,," I said it feels like a balance issue, I know ford have some oddities but I'm not familiar with them. He told me "my buddy Al ( whom I know) just put a new 28 ounce balancer and 28 ounce flex plate on."

    So what do I do? I'll tell ya!!!!
    I took his word that it was right,
    I bother you guys
    I research ford's goofy shit till my eyes bleed.
    Get 10 hrs into this mess
    Then I look at the flex plate.

    Problem with a ford ???
    Remember this -
    FORD (finished on right day)
    FORD ( firing order really different)
    BoilermakerDave likes this.
  29. town sedan
    Joined: Aug 18, 2011
    Posts: 1,290

    town sedan

    I work at a new car dealership and as we both know diagnosing a problem can often take more time than the repair (not sure about that in this case). Present the customer with a bill for you time to this point and an estimate for the repair. Then if they want they can take the vehicle back to "Al" to make right, or leave it with you to complete properly. Better idea every day of the week and they tried to used them all. That's why I love Ford.
  30. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,164


    It's not only Ford I had a neighbor buy a Chevy pickup with a fresh 383 we figured out it had a 454 flywheel.

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