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671 blower idle whine too loud?? differences in whine?

13K views 22 replies 10 participants last post by  CBUU2 
#1 ·
looking for opinions on the "loudness" of my 671 blower at idle. Noticed at a car show this weekend there were several cars with same set up as mine some were silent at idle, some a little noise and then mine, video attached



I know whine comes from belt/pulley, belt is set loose as it should be, noise is relatively the same looser or tighter and position on pulley does not change it either. pulleys are square with one another, top pulley appears visually to be a bit out of round as it spins but not showing up on square as out of round, snout flange is square too.
With belt off no noise comes from accessories, blower and belt adjuster spin freely/silently.
I have had this set up for over 10 years, always made sound but would like to quiet it down a bit at idle (old age??)

I know 8mm belts are quieter but trying to figure out how some with 1/2 inch set up exactly like mine are quieter. I did not see any holes drilled in pulleys or any other difference on other cars. youtube shows the same, same blower set ups and some are screaming some not so much. Maybe my belt and pulleys are just wore down but don't like guessing by throwing money at issues, besides the car runs fine.

There is something different but what??:confused:
 
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#3 ·
Belt tightness makes a difference. Try a little looser or tighter. Some belts just make more noise than others.
Make sure you have enough oil in the front cover.. Bottom of the hole behind the front triangle hole cover is about right. If you have a sight plug up to it. I run more in mine as it leaks a little. 90-140 gear lube might quiet it some.

It might just be a tighter blower too.
 
#4 ·
You don't want that belt too tight. I have a friend that just had the nose of his BBC crankshaft break off next to the front main bearing, i suspect that the belt on his 8-71 was too tight. That along with his external belt drive spaced the pulleys out a little farther than normal.
 
#5 ·
please use a stethoscope or a long screwdriver to listen to the blower snout bearings.. the idler bearing and the timing cover.. do you have Gear drive on the cam.. is that whats making the extra noise..

and a question... has anybody ever built a support bar that bolts to the front of block motor mount holes.. has something like a wheel hub and bearing assembly to mount the blower crank sprocket on and that is driven by a coupling mounted to the 3 bolts on the harmonic damper.. so the supercharger belt is NOT exerting sideways stress on the crank snout..

i also had an idea to create an Eyebrow sort of device with a waterpump mounted on one side kinda like the 3.1L/3.4L chevy timing cover for front wheel drive applications. this leaves a lot more room for blower belt paths right up the middle..
 
#10 ·
and a question... has anybody ever built a support bar that bolts to the front of block motor mount holes.. has something like a wheel hub and bearing assembly to mount the blower crank sprocket on and that is driven by a coupling mounted to the 3 bolts on the harmonic damper.. so the supercharger belt is NOT exerting sideways stress on the crank snout..
.
Yes, it already exists, called a Blower crank support. Can't tell you who makes them, but I have seen them and know thet are available.
 
#12 ·
Here is a crankshaft support.
Good vibrations Motorsport also has them

http://www.rbssuperchargers.com/Crank_Supports

You won't like the prices!

You really should not need one on the street. If you have a harmonic balancer I'd get rid of it and use a proper hub, even if it need counter weight. I have 22k miles on my blown sbc and no crank problems. I've never used a balancer on any of the blown motors I've built or owned.

I re listened to you video. It's hard to tell but as noted above I'd take the belt off and carefully turn the blower back and forth. You may feel a little backlash in the gears but not much. The video seems to have a lot of noise coming from the snout area so feel carefully for any roughness in the bearings. Same with the idler pulley. It's not uncommon for these to go away. As recommended above it won't hurt to change the oil and put fresh gear lube in it. Sometimes guys put castor oil in these but not for street use. It's old school now days.

I forgot to add this, in the video right at the start it looks like the blower pulley moves in an out. Check this too. It's possible to have spun a bearing in the snout and torn it up inside.
 
#13 ·
Dam that is loud and my first thought was you must have Gear Drive instead of a Chain, do you ???

I'm on my 10th Supercharged vehicle right now and I've had the whole line up; Roots, Twin Screw, & Centrifugal. The brand & design of the Supercharger are going to play the largest part of how loud it is. For example Whipple Superchargers are extremely quiet because they have multiple back flow ports, Kenne Bell uses a Helical Cut. The Current Procharger Centrifugal Supercharger I have on my Mach 1 has a Helical Gear Set and you wouldn't even know it was there, it's virtually silent. It's all about the Gear Cut and straight cut can be "extremely loud".

Of course worn or defective gears will be noisy too but at ANY rpm and becomes noisier as rpm increases. If you don't have gear drive and your SC has always sounded like that unfortunately you just have Straight Cut and there isn't much you can do to silent it.
 
#16 ·
Thanks for all input, suggestions, checked all. Still not finding difference besides as said above I simply have a straight cut belt and it is what it is. It's been loud since day1 so if something was going out it would have shown by now.

No slack in bearings, clearances are tight/square. Ran motor up to 3k -4K rpm with no belt in place, blower spinning fast and silent..... So that leaves belt contacting pulley = sound.

Now debating on new belt, pulleys-both or switch to 8 mm or just let it roll as is.

Thanks again for input, always open for more
 
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#17 ·
I think when rob talked about straight cut gears he was talking inside the blower. Not the belt. The gears the turn the rotors in the blower.
CORRECT :thumbup:

Here's a quick vid of my old 502 with a 871 Blower on it. Just my buddy backing it up in his driveway but as you can hear the SC is making no noise




I miss it..... :(
 

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#18 · (Edited)
That sounds awful loud to me and it doesn't sound like a whine. It sounds more like a clashing sound. Is it possible that the lobes of the blower are contacting each other only under a load like when making boost even at an idle? Possibly a lobe timing issue? I would take the carbs and top adapter plate off and check for any damage on the blower lobes or for any signs of lobe contact with each other. Is this a new blower that you purchased? If so call the manufacturer ASAP. More damage will occur if it isn't taken care of. I've seen situations where keyways were cut in the wrong positions that could cause timing issues. Let us know what happens.

https://www.facebook.com/Hampton-Blowers-114186331946831/

Check above site and call Hampton Blowers at 562-803-9484, M-F 7:30 AM - 6 PM Pacific Time

You could even send them your video to help trouble shoot. Don't run it as is.
 
#21 ·
Nothing out of time or hitting, dowel to ear reveals no sounds in case or snout, its always been loud, just never bothered me. Idling more these days so now I am noticing-it seems the pitch/tone has went from low/mild to high/screeching.
All feels good, tight and a road test did not reveal any weak parts. I bought the blower new in 2003 so no hidden history.
I have been talking to Don, he is my first resource, he has listened and gave me a few tips to try. I just feel this is something simple and I'm just overlooking it.
this is some great input from you and others on the site, thanks to all! I am leaning more towards wore out belt/pulleys.
I will ponder a bit more and let you guys know how it turns out.
 
#22 ·
Why haven't you called Hampton, BDS, Big Al's????

With the exception of ProStreetRob and BentWings; most of us are only familiar with a handful of setups, usuallhy the ones WE own.
As far as I know, Don Hampton is still alive and kicking. He, Mert Littlefield and Chuck Potvin were the Godfathers of a lot of this stuff. I think Don was Chuck Potvin's driver back in the day.
Hampton Blowers:
(562) 803-9484
 
#23 ·
Don is still alive and kicking, i have spoke with him and have as needed for last 10+ years. He has guided me well and gave me a few things to try to quiet it down, a bit quieter but still louder than most.

My original question was some are noisy, some not so much with same drive/belt - set up.
Just reached out to forum to see if anyone had any ideas on the sound differences between similar set ups, all suggestions are good and have ran through them all.
 
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