Hello, I dont think machining it thinner is the problem though. The problem is the ATI damper has a bigger hole in the front than the stock LT1 has. So the nub on the Procharger spacer is too small for the ATI hub. Thickness has nothing to do with the issue I'm having. On the stock damper the spacer fits tight on the front of the damper which centers it up. On the ati damper it doesn't fit tight so you have to rely on the bolt holes to center it, & needless to say it didn't do it for me.

 

Not really the drawing type. Sorry

He described it pretty well above, but will will elaborate some too.


There are two issues with the spacer when you switch to using an ATI hub.

First the spacer is too thick, so the pullies won't line up, so you need a thinner spacer. Most just machine down the stock one, but that is not the proper thing to do.

Second the nub on the spacer that is designed to fit in the stock balancer is too small for the ATI balancers, therefore the 3 bolts are all that is there to center the blower pulley, and they don't do it properly. Just the smallest missalignment will cause a bad vibration at high rpm's. I believe that is the reason we have seen so many supercharged LT1 guys with cracked ATI hubs, or broken cranks.

I have a local machinest/fbody owner, that has made several of them and made one for me, and it fit and worked perfectly. I've been running a maxed out D1SC, and now will be running a maxed on F1a.

PM me if you need anymore info.

Nick

 

OK. I got my new spacer today and installed it. Put my new belt on, started the car and put it in gear and started to pull out of the driveway and i could feel the vibration again. The spacer i had made by a local machine shop used my old spacer as a template and just made the nub bigger 2.047" to be exact so i dont think that is the problem. The only think left i guess is the tensioner. Does anyone else have any suggestions

 

OK. I got under the car again this morning, and found out that the blower pulley has a little bit of play in & out which i was told by ati is normal. Mine also has a little bit of play side to side. If you use your thumb and middle finger and place them in the center of the pulley I can feel enough play to hear it . it sounds like metal on metal. I drained the oil and it looked pretty good the were a couple little shavings in there, but that could have been in the pan from something else. I neglected to wipe it out first . I called ATI and of course the original owner didnt get the extended warrenty but no matter they told me the warrenty is not transferable which is BS in my opinion. Stand behind your product. Is there any place else this can be sent to check it out. I imagine it needs bearings, but i cant see spending 1000 plus for something that needs bearings. Is there someone on here who could do it

 

well i took the idler pulley off today and took it apart to check the bearings. They are fine. Im still getting a little squeal but the belt is tight. Im about ready to get rid of this procharger and have AI cut me another cam. Im tired of messing with this.

 

Find out how much end play and lateral play is allowable and measure it with a dial indicator.

If it is out of specification then I would seriously consider getting the unit rebuilt by the manufacturer.

It sounds like you purchased a 'used' head unit or kit. If that is the case then I would not expect the manufacturer to correct the condition for free. A valued supplier may analyze the blower in question and work with you, but I would assume, quote you cost to rebuild. Make sense?

First thing is to measure play in the shaft because we don't know this is causing your vibration issues, right?

 

No i don't know that is the cause of the vibration. But actually the more i feel and hear it sounds more like a hammer lightly tapping on metal, but in at a rapid pace. It mainly does it when i pull up to a stop sign and stop. Ill be in first gear and i can hear it. If i put the car in N it goes away. As soon as i put in gear again i can hear it until i start to pull away. once the rpm gets up past 1500 it goes away. And it only does it when the blower is running. If I take the belt off its never a issue

 

Hey 600,

I can sense your frustration. I wish I had a fix for ya rather than more questions. Hope it doesn't seem that anyone here is giving you a hard time

Sounds like it (the vibe) is related to engine load at idle. Starting to sound like something un-related to the blower itself.

-Scott.

 

No i don't think im getting a hard time at all. I appreciate all the responses. I know this is a strange problem im having.

So is the engine load at idle a normal thing, and if so why does it only do it with the blower running. and is it going to hurt anything, thats what im afraid of. i just put 12000+ in the engine build not counting the blower so thats why im a little worried.

 

Ok ive pretty much tried everything and still no progress. I guess im going to take the blower off and send it in to get checked. Before the new engine build when the car was at idle the blower had what sounded like a nice whistle now when at idle you cant really hear anything and when you give it a little throttle it sounds like a whine very different from before. The only thing i can think of is the car sat from april to mid august maybe the bearings went bad.

 

I had a p600b on a 383ci LT1. I had many vibration issues running a 8 rib belt. I now have moved to a D1, but, now I do not have any vibration problems. Here is what I did.

The ATI driver pulley must be mounted to a pilot to center rotation true with the crankshaft and hub. I machined my alum hub to do this. Measured the runout. Not more than 0.010 inches @ worst.

The Driver and driven pulley must be in alignment within 0.050 inches. Angular and offset. I used a long straight edge and feeler gage with pulley rotation @ 90 degrees increments. Adjust your blower mount spacers (with washers or shims) to get them in alignment.

I have found that the belt vibration issue is due to the blower under load and off load. The belt tension will switch from bottom side to top side when load is on/ off respectively. Since the ATI belt tensioner does not have any damping design, the idle pulley will vibrate wild when this tension changes. So, I designed my own solution. It works.

I have posted pics of my idler arm vibration solution on photobucket.com Search under my sig... "mzgp5x"

Also, this design allows me to load the ATI idle tension screw less, which will lower the canteleverd load on the crankshaft snout, and, provide less bending moment stress and fatigue loading. The "stop" will limit the idler arm amplitude (I recommend about 0.050 inches max.). The stop is fixed to the 3/8-16 bolt @ the WP. Replace the ATI with a longer threaded rod stud and mutiple flange nuts (I used 3). Stop is machined from a 1/2 by 1 delrin stock.

Tighten all the idler fasteners (even the large 3/4" @ the rear of the idler arm).

Also, the p600b unit has a very small input shaft and key. Make sure you have full pulley engagement, and, the key is not rolled inside the driven pulley hub.

Hope this helps. B. 97ss M6 383 D1. Sorry for the long rant.