Since I can't find a lower priced SFI certified damper except the ones from ATI, I thought I might as well order one.
I must add, I'm only looking for the shell less hub with a 6.78" OD.

The trouble is, Summit etc. state the correct part# is 917 071. On the ATI site: http://www.atiracing.com/products/da...ts/damserp.htm they say it's the part # 917 07144. I have written to ATI but no response up to now.

Does anyone know which part # is correct???

Thanks

 

Has anyone tried to mount an ATI damper using a stock hub????

 

No,
It wont fit.
Different dimensions entirely.
You need the ATI hub with shell.
part # 917 07144 is the right PN# from ATI
or #275 from the chart for the complete assy. with steel hub unless you want the aluminum hub.

 

Rick I know the ATI hub is much longer but what is with the bolt pattern???

 

The ATI hub uses 6 bolts. The ATI hub is longer. So, even if the bolt pattern was the same (and it's not) it still wouldn't work on a factory hub because the offset is wrong.

If you want to use an ATI balancer, you have to use the ATI hub. Note: the ATI hub cannot be removed with the engine in the car.

 

I recently asked ATI about which damper they would recommend for my LT1 396 stroker motor. The response was:

So he's recommending for LT1/LT4 stroker motors, and it may be applicable for non-stroker motors, the 7.5" OD Aluminum Shell w/hub P/N 971269.

 

If I do buy one it will be the 6.78" part # 917275.

The OE damper is 7.15" so by using the 6.78" damper I might be able to use the stock belt.

 

Vettef6,
You will find the stock belt will be too loose for proper tension using a 6.875 damper. You will have to either run a shorter belt by I think about an inch or raise your alternator some as I did using a make shift adapter and modifying my bracket for max alt. bolt travel.
I never actually measured or calculated the belt length difference with the smaller damper but it's more than you think.
Just move your alt to highest point and check the belt tensioner pulley with the stock belt installed and you will see just how much load you actually have on the belt.
I have used this ATI #275 6.875" size damper on two different C4s.I considered the aluminum hub to reduce rotational weight but with the increased press fit required on the crank,I didn't want to deal with having to heat the hub for install.Also, it's tight but I'm able to get the engine out of the car with the 6.875 damper on. You have to raise the trans up in the tunnel with the engine to the max in order to clear the steering ram. I don't think the 7.15" damper would let you do that.
I have pulled the engine out of my car 3 different times for cam changes with this damper on with no problems.
Rick

Rick

 

My ATI is REALLY, and I mean REALLY, close to the frame at the front. So much so that I had to grind the mounting bolts for clearance.

Speaking of bolts, my ATI calls for an one-off torx bit; the T50 was a tad too small and the T55 to big. Summit sells a T50+ (from memory) that fits.

I don't recall the part number of the ATI I bought; I built the 388 in early 2007, but it was the steel hub version.

Jake

West Point ROCKS!

 

Jake,
ATI apparently changed the 3 front mounting bolts to round head allen socket for the later dampers. My #275 I bought in 2002 had male torx heads that stuck out 3/8" inch giving only about an 1/8" to the frame. Too close for comfort. I machined the heads down about an 1/8" for more clearance.The #275 damper I bought in 2006 had the low profile round head allen socket bolt which gave about 3/8" clearance.Don't know but I guess ATI might have heard about the clearance problem.
Rick

 

Boys thanks a lot for the info.
I will then order the 917 275 damper and see how I can make the stock belt fit.
Rick you stated you made a shift adapter and modified your bracket for max alt. bolt travel.
Do you have any pictures or drawings??

 

Sorry,no I dont.I just elongated the slot a little at the top to give me a little more travel but it wasn't enough. I then just made an aluminum rectangular square block and drilled and tapped it on both ends to use as an alternator mounting hole extension. Being a machinist made it easy to do but the other reason I did it that way was to give me more clearance at the front to be able to run the aluminum proform valve covers since their not notched for alternator clearance.If it wasn't for this,I would have just used a shorter belt. If you run a cloth tape measure around the pulleys to simulate the actual length needed and allow a little for the tensioner travel ,you should be able to match a belt to it at your local auto parts . Sorry, this is the best I can do.
Rick

 

I'm curious as to why your soinsistent on trying to get the stock belt to work? You can get a non-stock belt to fit without any additional modifications as they come + and - sizes from stock and you know the fit will be right.

Additionally, based on the ATI recommendation I received why not just go with the bigger 7.5" damper now that you know the stock belt won't work with the 6.78"?

 

ATI uses the T40 Plus Torx Bit (918997) $3.81) on their Damper Accessories page.

 

No-one sell or knows the shorter belt part number?

Can do a new set-up using the factory hub/balancer?

 

Thanks for correcting me on that.

I had T50 on my mind since I'd been searching for a bit that works with the valve cover bolts on my son's LT1.

Jake

West Point ROCKS!

 

Sorry, can't remember the part number.

I bought my new belt by first using the tape measure method, then trial and error; exchanging the first belt I bought for a different length.

Being close to AutoZone was a real plus.

Jake

West Point ROCKS!

 

I would like to use the stock belt because I already bought one. I also bought all the pulleys to convert to a single sided serpentine belt, since mine is a '92 and has a double sided one. I ruined three belts so far and two dampers!! I've had enough, and this is why I'm converting and going to a SFI damper.

Since my damper measures 7.15" and I rev up to 6800 rpm at the moment, I would never use a larger damper. No need to run the accessories, steering pump, AC etc. at higher rpm than needed.

The correct belt length should be about 3/4" shorter than stock.

 

I have the ATI 6.78" balancer on my 383. The stock LT4 belt works fine.

Edit: Sorry, just realized you have a '92

 

Thanks again GS. PM sent