[Steve C.]

Used the ATI p/n 917160


.

[charlie66]

Originally Posted by 455-4+1

I bought the Romac a few years ago (steel hub, aluminium outer) would not fit with a Moon or stock timing cover. Emailed them with CAD drawings and photos showing the areas of interference. They told me they were CNC machined so couldn't we wrong LOL.
Showed them all the info again and reply was "what do you expect me to do about it ?".
NEVER AGAIN !.

Can you make the difference up with a spacer in-between the timing gear and the balancer ? Maybe use a old balancer and cut what you need off of it for the spacer..

Just a thought....

[Skip Fix]

Interesting on the Romac! I have one havent; used I got from KRE.

I have an ATI I got in about '89. Must have been one of the first ones they made. Hub and outer ring has Chevy bolt pattern but locates a Pontiac pulley(RARE can drill them 4 bolt and 3 bolt). Had to lathe out the hole for the balancer bolt washer was too small. and shorten the hub 0.125 to line up the pulleys.
Have a Pioneer SFI on the 400 in the 81 and on the new 455 for it. I have a BHJ on the shelf that I had them do the updated outer ring(some spun) and cut the outer ring with a chamfer to clear the A/C pulley

[cgeise]

I also used the TCI rattler with out issues for a long time - and have one for sale now

[gene simmons]

Originally Posted by 455-4+1

I bought the Romac a few years ago (steel hub, aluminium outer) would not fit with a Moon or stock timing cover. Emailed them with CAD drawings and photos showing the areas of interference. They told me they were CNC machined so couldn't we wrong LOL.
Showed them all the info again and reply was "what do you expect me to do about it ?".
NEVER AGAIN !.

I have the all steel Romac . Mine was close to the pan like yours in the second photo,which seems to be typical,other than bending the pan lip back,it fit everywhere else just fine on a stock timing cover and have had no issues.

[Aaron Quinton]

There are basically 4 different types of torsional damper technology. Their job is absorb torsional vibration at the front of the crank (most displacement) to reduce torsional stresses in the crank to allow the crank to deal with more load in torsion.

1. Elastomer damper - these types use rubber rings or biscuits to isolate the inner hub from the outer hub. This type of damper is "tuned" based on the stiffness of the rubber and inertia ring to target the highest torsional activity frequency and split it. The splitting moves the activity higher and lower in frequency to an area where there is less total torsional stress allowing to crank to live. ATI is a good example. Most factory gasoline dampers are this style.

2. Viscous damper - this type of damper uses an inertia ring isolated from the crank hub by a viscous fluid. This type of damper operates at all frequencies instead of 1 frequency like an elastomer. These are more expensive dampers. Fluidampr (Vibratech TVD), Hasse & Wrede and Metaldyne are examples of these.

3. Frictional damper - this type of damper uses "wet clutch" friction material to interface with the outer hub. Innovators West is an example of this style.

4. Pendulum damper - this was first used on in early radial aircraft engine technology. It uses metal pucks placed in holes in the hub to absorb the torsional vibration. The hole and puck sizes tunes each hole/puck to a given frequency to absorb torsionals at a problem frequencies. The TCI Rattler is an example of this style.

Originally Posted by PontiacMatt72

I know nothing about a damper, so can someone explain the difference between the ATI and any other damper? What makes it so much better?

[ponjohn]

What about Innovators?

[BruceWilkie]

Originally Posted by ponjohn

What about Innovators?

See # 3
http://forums.maxperformanceinc.com/...8&postcount=26

[marks73ta]

I'm using a used ATI Pontiac hub balance. Three bolt with the Pontiac center alignment ring. I'm using BBC crank pulley/pulleys but it also had fitment issues with the Moon front cover. I used two spacers (can't remember their individual/combined widths) sold for Ford cranks. Worked great. I believe I got them from Good vibrations motorsports. I cut off the Pontiac pulley locating ring to use the Chevy pulleys.

[frbformula]

Cgeise i sent you a pm

[455-4+1]

Originally Posted by charlie66

Can you make the difference up with a spacer in-between the timing gear and the balancer ? Maybe use a old balancer and cut what you need off of it for the spacer..

Just a thought....

Initially I machined the Moon cover and beat on the pan for clearance, then went to a belt drive / motor plate so no clearance issues. The issue was the distance from the rear of the snout to the back of the balancer hub, 1.536" on a stock Ponty and only 1.167" on the Romac. This means the rear of the balancer hub is approx 0.395" closer to the timing cover and oil pan.

I have seen small spacers used before, but am definitely not a fan of another bit of metal between the hub and the crank (as well as the piss off of getting one made !!!)

[455-4+1]

Originally Posted by gene simmons

I have the all steel Romac . Mine was close to the pan like yours in the second photo,which seems to be typical,other than bending the pan lip back,it fit everywhere else just fine on a stock timing cover and have had no issues.

Maybe the steel one has a smaller retaining lip on the rear of the balancer hub (aluminium one needed to be thicker ??) . On the aluminium one this extends approx 0.395" further back than a factory one causing issues everywhere.

Their response got me going worse than the fact that it could never fit in the first place !

[PontiacMatt72]

Thanks Aaron! Good info there.

The next question I guess would be, is there any quantifiable evidence explaining the superiority of say the ATI over the all-steel Romac? Or is it essentially just the one with the least failures and the highest price tag?

[gene simmons]

Originally Posted by 455-4+1

Maybe the steel one has a smaller retaining lip on the rear of the balancer hub (aluminium one needed to be thicker ??) . On the aluminium one this extends approx 0.395" further back than a factory one causing issues everywhere.

Their response got me going worse than the fact that it could never fit in the first place !

Its possible with the aluminum that it is slightly wider than the steel,but my steel is rather wide.
Without measuring it,i think the hub distance must be correct,since my crank pulley lines up with the others.
They could have made the center hub with a larger dia. or the balancer not as wide,that probably would have given the clearance needed.

I would agree with you,that is a poor response on there part.

[Aaron Quinton]

I've not worked with an ATI or Romac so I can't say which is better or why. I do know that the engineering going into simulating or measuring torsional vibrations in an engine and effectively targeting the highest torsional energy will be the most effective in application.

ATI used to have a really good technical page on their site explaining how their dampers work. It looks like it's disappeared now.

Based on what you here from users, it sounds like ATI has done a really good job on the target frequency with their damper.

I personally like the viscous style damper because it absorbs at all frequencies.

Originally Posted by PontiacMatt72

Thanks Aaron! Good info there.

The next question I guess would be, is there any quantifiable evidence explaining the superiority of say the ATI over the all-steel Romac? Or is it essentially just the one with the least failures and the highest price tag?

[johnta1]

Article on Dragzine:

ATI damper

[BruceWilkie]

somewhere on here in last couple years there was a brief blurb about critical frequency range. Showed rpm a late 70's 400 cast crank combo with hub not damper hit critical frequency range. Was rather low. (@4k)

More info on how this is determined would be good to know. Its logical cast forged or billet will have differing critical frequencies.

[chiphead]

How about this guy

https://www.summitracing.com/parts/s...w/make/pontiac

Or this one

https://www.summitracing.com/parts/p...w/make/pontiac

[frbformula]

The professional products one is the one i spun thd hub on. Tin indian only rates the to 500hp. I was not aware of that when i bought it a couple years ago.

[Nicks67GTO]

Why doesn't anyone use the SFI Pioneer? I never see it mentioned in these discussions. American made, priced nice, no mods necessary, SFI certification...I'm using one on my 434 build.