Thread: Chev blower drives

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Got a question here about the vibration dampers on chevy small blocks. If the power used to drive the blower is getting up a bit or if there is a severe backfire, it tends to fail the stock damper by either striping the bolts out or splitting the casting.

Now either you can get the aftermarket dampers that are stronger. Or as I have heard (read) you can get a steel hub that replaces the damper and drives the blower bottom pulley directly. Weiand used to make them, I think. Either they were for street or competition.

What I am trying to figure out is does this apply to aftermarket internally balanced 383 chev stroker cranks ? Is the blower belt going around the bottom pulley enough to soak up the resonace (vibration) that the crank is putting out at high revs ? I's for a street strip fun car.

i have built some blower engines and i would not let someone talk me in to a steel hub . look at a ATI or a TCI or FLUIDAMPR they all will work with a blower and the powerbond to.harmonics will kill a engine and valvesrings etc so i would not run the steel hub.i do not see how the belt could soak harmonics the amplitude of vidration can be any were in the rpm of the engine and needs to be damper if you let it run wild bad thing will happen

Originally posted by southerner
Got a question here about the vibration dampers on chevy small blocks. If the power used to drive the blower is getting up a bit or if there is a severe backfire, it tends to fail the stock damper by either striping the bolts out or splitting the casting.

Now either you can get the aftermarket dampers that are stronger. Or as I have heard (read) you can get a steel hub that replaces the damper and drives the blower bottom pulley directly. Weiand used to make them, I think. Either they were for street or competition.

What I am trying to figure out is does this apply to aftermarket internally balanced 383 chev stroker cranks ? Is the blower belt going around the bottom pulley enough to soak up the resonace (vibration) that the crank is putting out at high revs ? I's for a street strip fun car.

i've run them with and without a bal. southerner, and didnt see any dif. BDS told me i didnt need one. if you are having severe backfire then something is gonna break and i had just as soon it be the hub. never broke a hub, but i've blown head gaskets out from the head, and bent rods and broke cams, so if you fix the hub then something worse will break, so that might not be so bad. get enough fuel flowing and you want have that problem. ha ha ha

Hmmm , yeah I have actually seen one of my crankshaft noses get bent .010" out of allignment after big backfire, and that was with a stock vibration damper on it, but it must of weakened it because the next backfire split the damper through the keyway hub and everything just basically fell off. That was with a 355 chevy, so now looking at the 383, would the trick be to go for the SFI internal balanced damper as it will keep the safety guys happy ?

the small block crank nose is very small to drive a 3 inch belt and no one will warranty the small nose crank for this use. one with a big block nose would be better the belt will dampen the harmonics from the blower but will not work on all the harmonics in the engine

Originally posted by southerner
Hmmm , yeah I have actually seen one of my crankshaft noses get bent .010" out of allignment after big backfire, and that was with a stock vibration damper on it, but it must of weakened it because the next backfire split the damper through the keyway hub and everything just basically fell off. That was with a 355 chevy, so now looking at the 383, would the trick be to go for the SFI internal balanced damper as it will keep the safety guys happy ?

when you buy a new blower kit you dont get a HB with it,you get a hub. the belts are suppose to do the job. i think if you hang 10 more pounds on the crank is just gonna make it worse. fix the backfire and you want have to worry about the HB. when it bacbfires the blower stop turning, so something has to give. fix the pop back.

Originally posted by lt1s10
when you buy a new blower kit you dont get a HB with it,you get a hub. the belts are suppose to do the job. i think if you hang 10 more pounds on the crank is just gonna make it worse. fix the backfire and you want have to worry about the HB. when it bacbfires the blower stop turning, so something has to give. fix the pop back.

here are some hubs from BDS

yes the damper is heavy but it dose not hang out there the 3 inch belt dose. you can run the hub if you want .but it will not work on the harmonic or torsional vibration or help valve timming accuracy and help with any harmonic that get thru the timming set to the valve springs. unless you have a belt drive for the cam the damper are 6.25 dia is 5.5 lbs and 7.00 dia is 7.9 lbs int.bal dampers i bet some of them hubs are verry heavy and it would not be that much of a deference. the small damp 5.5 and the steel hub?

Both of ya'll are missing the point. If its still popping back when he puts that hi dollar HB on, all he is gonna do then is break a 300.00 HB or something else instead of a 50.00 hub. the HB is not making it pop back. It may or may not help save the bearings in the long run, but its not gonna do anything for the popping back. that's what's breaking the hubs. if they were nessary BDS would be trying to sell one to everybody that ever owned a blower, and they don't. if its was nessary they would sell one with the kits. i'm gonna say it dont do nothing one way or another. i'm talking 3" belts, never run any thing else.

Originally posted by lt1s10
Both of ya'll are missing the point. If its still popping back when he puts that hi dollar HB on, all he is gonna do then is break a 300.00 HB or something else instead of a 50.00 hub. the HB is not making it pop back. It may or may not help save the bearings in the long run, but its not gonna do anything for the popping back. that's what's breaking the hubs. if they were nessary BDS would be trying to sell one to everybody that ever owned a blower, and they don't. if its was nessary they would sell one with the kits. i'm gonna say it dont do nothing one way or another. i'm talking 3" belts, never run any thing else.

i do not see it ?? stop make it pop back the good damper will not breakBUT the key ways may go to hell .bds dose not sell dampers but they sell hubs they are cheap for them to make . and they can not make a damper like ati or tci and not get sued by them . if the belt controls harmonics ??than a car with a serpentine belt would not need a dampen?

Good feedback guys, but perhaps I had better clarify on the issue, this 355 I had the problems with and breaking dampers, we tracked it down to the vacume secondary Holleys secondary stages hanging open a bit after I got my foot off the accelarator. Cured that problem by putting 2 holley 650 double pumpers on, bingo no more backfires. I sold that car on a few years back.

Now I am building up a sleeprer Holden HG ute, built the motor up and everything................ Then I changed my mind, going the 383 stroker motor with the internally balanced crank and a nice big 6 71 hanging out the bonnet, I will be using 2 Edebrock 1405 600 cfm carbs because they are nice and compact. so much for the sleeper idea when you want to have fun. Still got the original 350 it is going into another project. I only raised up the idea of running a vibration damper verses a steel hub because of the longer stroke of the 383 3.75" as against the 350 3.48" strke was with the longer stroke would there be more Harmonics happening lower in the rev range ? And I will be driving the blower 1 to 1 so that will be putting some mofe strain on the crank snout and harmonic balancer.

the damper if you take the ring off it you have a hub? so why not run the damper it will take up the harmonics ?? the snout of the small block with two key way one at 12 and 6 will not leave much steel for the snout i would cut the crank for one long key way and run as much press as you can on it and be done with it .the two key ways take steel out you do not have and you split the press on a small snout i do not like this

Originally posted by southerner

Good feedback guys, but perhaps I had better clarify on the issue, this 355 I had the problems with and breaking dampers, we tracked it down to the vacume secondary Holleys secondary stages hanging open a bit after I got my foot off the accelarator. Cured that problem by putting 2 holley 650 double pumpers on, bingo no more backfires. I sold that car on a few years back.

Now I am building up a sleeprer Holden HG ute, built the motor up and everything................ Then I changed my mind, going the 383 stroker motor with the internally balanced crank and a nice big 6 71 hanging out the bonnet, I will be using 2 Edebrock 1405 600 cfm carbs because they are nice and compact. so much for the sleeper idea when you want to have fun. Still got the original 350 it is going into another project. I only raised up the idea of running a vibration damper verses a steel hub because of the longer stroke of the 383 3.75" as against the 350 3.48" strke was with the longer stroke would there be more Harmonics happening lower in the rev range ? And I will be driving the blower 1 to 1 so that will be putting some mofe strain on the crank snout and harmonic balancer.

Do what ever you think you should do Mike. I'm going with the people that has thousands of these thinks on the st. if they ant got it right by now, then I don't know what to say. I sure don't know more about it than they do.