The search function is disabled so I'm forced to post this. I have two harmonic balancers. One is a 351M balancer, and the other a 400 balancer. I messed up when I went on vacation, so now I can't tell with 100% certainty which is which. I know that some say you can use the 351M in the 400 and vice-versa, but I believe the prevailing wisdom is that they are different.

The side of the smaller one is D5AE AA and has a slot/groove cut, stamped HH on front, and the back is stamped 6316 and RE 1.

The bigger balancer, the one I think is the 400 balancer, is D1AE AA with no slot. It has nothing legible on front except maybe a Ford logo, and back shows 6316, and RA.

Hope this isn't detail overload and sorry to have to ask, but I'd appreciate a response while I see why I can't search!

 

Hey this might help you, I am currently rebuilding my 400 so i took a look at the damper on it. I have a 351m in the back of the shop that i compared it to and this is wat i found. I didnt notice much of a size difference but i noticed that on the very outside ring of the 400 damper there is two sets of holes drilled half way through the damper, one set with 3 holes and the other with 2. On the 351m damper there is 10 of these holes on the outside ring all in a row. Hope this helps.

 

Interesting... the bigger balancer has 5 holes on the outer ring and three in a raised platform on opposite side. The other has the three on the raised platform but none on an outer ring. These probably vary according to the variation needed for balancing. Thanks for replying. I went to BubbaF250's site and looked up the ID no.s. The D5AE AA is shown under 351M but the D1AE AA isn't listed among the 400 parts.

 

ya that makes sense i kinda thought that too but i figured it was worth posting

 

o heres another thought, maybe the D1AE isnt for a 400 at all if it isnt listed under 400, when i compared mine there was no size difference, this balancer might be for a 460 or something since it is bigger and not listed under 400. I could very well be wrong im no expert, just my 2 cents.

 

Thanks again for the reply. Actually, I didn't look at the geometry as closely as you did, and immediately went to mine to look at them to compare with yours. It was worth a try, it's just it turns out their all different. If they were consistent like yours we might of been on to something there.

I can't vouch for the origin so it's possible that it is from another engine and i'd like to verify it. Maybe someone else got more numbers than BubbaF250 and can match them up.

 

as far as I know all 335 engines require the same balancer. There might be a difference between 351M,351C,and 400 balancers but its not in the balance as they all use I believe 28oz balancers.

 

I was going to weigh them before posting but my wife threw away our scales some time ago.

Anyway, a rudimentary test shows they do no weigh the same, the bigger one appears to outweigh the other. It's more massive, and both are iron. Admittedly it's not a perfect test without scales. And with holes drilled etc. they could be the same.

Some long time ago, when I first considered this 400 rebuild project, I researched threads discussing the harmonic balancer topic. Overall, I was researching interchangeability of parts.

I hadn't quite bitten in to doing the rebuild myself for lack of experience. Armed with information gleaned from FTE, I called a major rebuilder for this region since they did 400 rebuilds. They spoke about the relative merits of a 400 over 351M and this seemed to follow the FTE recipe for building torque favoring, higher horsepower engines.

One thing was they said their parts guide showed the balancers to be interchangeable. I posted this statement and the responses convinced me then that there was a significant difference between the two. The reason, if I remember this correctly, is that the extra half inch displacement and difference is piston sizes is enough to make the balance between the two different, all other things being same.

Made sense, that's why I'm on the hunt for this.

 

Went to archives. Posters state that parts places list same damper for both engines, but some are saying this is to have greater coverage for inventory items. Factory had different dampers purportedly, but others cite interchangeable dampers between 400, 351M and 351C. Major point favoring not interchanging them is that since both are externally balanced and have different strokes, (400 crank is longer w/shorter piston), then they require different balancing.

Still, Kopfenjager, as you and others in the older posts stated, both engines use 28oz. So, if my balancers don't weigh the same, then Matselland you could be on target saying it may be from another family of engines.

I have to mow the grass and chip some limbs, so I'll wait a bit for a few more replies before putting on the balancer that matches BubbaF250s parts list.

Thanks for the help guys, and if you come up with something more let me know. I am not going to internally balance this baby but like to keep it by the FTE book.

 

crawl, your larger/heavier balancer is the 400, it has more mass to it for the additional stroke of the 400. the slightly smaller/lighter balancer is the 351. both are 28oz imbalance, both will physically interchange to any 335 engine and not cause any major balance issues. the drilled holes in the outer ring are prolly the factory balancing to the crank. you are holding in your hand what many have pondered, questioned and disbelieved over and over again for a long time. this IS assuming that they are both 335 balancers, if they are not you would notice a major difference between them. the closest would be from a W, smaller overall and different height from seal to the pulley flange. so are they about the same, just one a hair bigger/heavier?

 

Thanks once again for the detail in your answer.

One balancer / damper came off my 351M and the other off a 400 block I bought for the crank. I suppose someone could have swapped the 400, but have no reason to think they did.

Holding both up against each other they appear to be same outer diameter. I'd be surprised, but not too, if they both weigh in at 28 oz though. The overall depth from front to back is same at 3 in. The one I call larger has a timing surface of 1 1/4 in. thick and the smaller is 3/4 in. thick. Drill outs and such could equalize the weight though.

After reading your post, I'm convinced the stroke is enough to make me want to go with the bigger balancer for my 400.

Thanks everyone, hope someone else can put the question to rest too.

 

the 28oz thing is not the total weight but the amount of the added weight needed to balance the crank, which is not in balance without the damper on it. look at the center hub and you'll see a section of added weight. your flex or flywheel also has a weight on it. being that it is added to the outside of the engine makes the 335 engines externally balanced. some engines are internally balanced stock, but it is mostly a high-end racing thing to have your engine internally balanced. and pretty expensive too.

 

That explains things and voids the confusion over what I was looking at, which seemed to weigh more than 28 oz. Thought my bud lifts were finally paying off...

Brings up another question though, since the external balancing is accomplished using both a harmonic balancer and flywheel / flexplate, and the 400 requires a 400 balancer, does it also require a 400 flexplate? Mine didn't come with one. I intended to use the flexplate from the 351M since it wasn't missing teeth and otherwise appeared okie-dokey.

 

The balancers should not weigh 28 oz. I think the 28oz is the balance correction not the over all weight. The 400 should be a bit heavier to make up for the weight in the crank. I also think it would be important to have the right balancer from the factory spec. I've seen a lot of toasted bearings and leaking mains on these motors and I hink the proper balance will be important.

I am spending the $200 to have my motor balanced before it goes together.

 

Roger, what's the intended purpose for your build? Mine's a weekend work truck, mainly, and maybe if I get lucky and venturesome, I'll put one of those popups on it and do some fishing at the lake on occasion.