470 vibrations and resonance

[natemoore]

My 470 is popping alternator bolts...not only the ones that hold the alt to the bracket, but also the ones that hold the two halves together! Had to use some bungee cord to keep it together.

I know that an inline engine isn't going to run as smoothly as a V-6 or V-8, and I'll bet these after-market alternator add-on kits probably aren't engineered either.

My kit, which looks like a Breezeworks kit (can't remember), is for a 470 with P/S. Both the upper bracket and lower bracket bolt onto the front cover. The upper bracket has the adjustment slot and is forward of the alternator. The lower bracket is aft of the alternator. This setup appears to be wreaking havoc.

I'm thinking about installing larger Grade-8 through-bolts in place of those skinny bolts holding the two halves together. Any comments or concerns on this?

I may add an additional bracket. If you've done this, please post pictures.

Lastly, I'm noticing some resonance at mid-rpms. Kind of sound like "womp-womp-womp-womp" and it's direcly proportional to the rpms. At higher rpms is goes away. It could also sound like "choo choo choo choo." Is this unusual?

 

[Don S]

Re: 470 vibrations and resonance

From your other thread before you posted this one.

The vibrations are why a lot of the cheaper alternator kits just don't work. They can't hold the alternator solid enough to prevent vibration, and you see what happens when you have a lot of vibration. The crankshaft pulley on the 470 is also not the most perfect pulley known to man. It causes most of the vibration.

 

[natemoore]

Re: 470 vibrations and resonance

Do you have a recommendation? My kit looks identical to the Breezeworks kit, the only difference being the bottom bracket, which on mine mounts to the back of the alt, and on the most recent Breezeworks kit, it appears to mount in front of the alt. It was over $300, BTW. That I do remember.

 

[jayrodoh]

Re: 470 vibrations and resonance

Can you go back to the stator/regualtor system? I replaced my regulator with the updated one 4 or 5 years back and have had zero issues since then. Sounds like an alternator kit may be close in price.

My 470 runs pretty smooth after the first 10 - 15 seconds of startup (took a few attempts to get the choke set to avoid cold shaking).

 

[dn010]

Re: 470 vibrations and resonance

Inline engines are actually supposed to be smoother running than the "v" engines due to the fact they are naturally balanced. The 470 on the other hand isn't a very smooth running engine with real low rpms. But if is tuned right and set to the correct idle rpm it should be really smoothe running...

 

[EddiePetty]

Re: 470 vibrations and resonance

I made the alternator conversion several years ago and I, too, noticed a vibration beginning at about 1K rpm. I happened to notice the 'return' side of the drive belt was vibrating like a bass fiddle. I played around with adjustments and found that if the shortest belt possible is installed the belt slap (and thus alternator vibration) disappeared.
Now the only time I notice a vibration is as the engine is still on choke. Once the choke has pulled off the belt is stable. HTH

 

[natemoore]

Re: 470 vibrations and resonance

I guess I need to upload a video due to the subjective nature of interpreting the "choo choo choo choo" comment. I think it idles fine, but the alternator is pretty far out from the center of the engine. I probed around with my mechanics stethoscope and found that I couldn't even bear it when I put it on the alternator. Ouch! The rest of the engine sounded sweet. I think my "womp, womp, womp, womp" is coming from the alternator. When I remove it, I'll run the engine and report back.

I could go back to the stator if I wanted to drop another $450 (I tossed out my stator when I "upgraded"). I'd rather solve the bracket problem for a lot less....I have a welder

 

[natemoore]

Re: 470 vibrations and resonance

Inline engines are actually supposed to be smoother running than the "v" engines due to the fact they are naturally balanced. The 470 on the other hand isn't a very smooth running engine with real low rpms. But if is tuned right and set to the correct idle rpm it should be really smoothe running...

Well...comparing my V-8 Tundra to my old I-6 Ford F-100, I'm not sure my experience jibes with that statement.

 

[dn010]

Re: 470 vibrations and resonance

Well...comparing my V-8 Tundra to my old I-6 Ford F-100, I'm not sure my experience jibes with that statement.

You're trying to compare new technology to old there.... Nonetheless definitely try to run it without the alternator and see. Can you post a picture of what ya got?

 

[natemoore]

Re: 470 vibrations and resonance

Okay. Found the problem with the vibrations. While scouring the internet for kits, I found one that had a third bracket. Holy crap! I vaguely recalled having a bracket left over that I--for the life of me--couldn't figure out where it went. The directions left a lot to be desired. Sure 'nuff, the bracket I thought was just "extra" actually had a home.View attachment 107771

As for it not charging, I forgot to remove the plastic Q-Tip handle I used to retain the brushings when I assembled the two halves. Although this is a boneheaded move, I am forgiving myself because I was in such a hurry to get the boat together and in the water.
View attachment 107772

Anyway, the alternator is toast from being rattled around so much. But knowing what is wrong is a huge relief.

Remember, it takes a big man to admit his mistakes. :redface: