rcdynamic88

Looking at replacing the balancer/dampener on a 1965 330 with an aftermarket one with all the degree marks. I see many aftermarket versions available and some say they are for 307,330,350,403 SBO and 400,425,455 BBO, and others say they are for the 400,425.455 only. Are all Oldsmobile balancers/dampeners interchangeable? Should they be internal or external balance type? What is the difference and how do you know what your particular engine uses?

I was looking at this one on eBay:

http://www.ebay.com/itm/OLDSMOBILE-F...c07f23&vxp=mtr

Another vendor has what looks like the same part for $85 but their ad says 400,425,455:

http://www.ebay.com/itm/201154322176...%3AMEBIDX%3AIT

What are you guys using on your Oldsmobile's?

Run to Rund

1965-67 balancers have different counterbalance than 68-up, and the timing mark is in a different spot so you need the correct type pointer/tab.

rcdynamic88

I was searching other Oldsmobile sites and I found a post on oldspower.com.

http://www.oldspower.com/vb/showthread.php?t=38670

I am mainly interested in 425racer's reply:

"I have a question. I have had four 330 cranks in my builds over the years. Up until the 380 I used 350 balancers with no problems. I now use an ATI SFI approved dampner. Shouldn't I have had problems? Oh and the first 16-18 yrs of racing I never had a motor balanced."


The OP in this case was dealing with a 65 2 bbl motor that has just a hub. At least my 65 4bbl has a balancer with a counterweight that is similar to all the 350 dampners I have been looking at. Also, the timing tab on my 65 Cutlass is on the drivers side like the 350's and 455's. Wouldn't the TDC mark end up in the right location on the pointer?

oddball

I'd recommend staying away from any dampers that don't have a brand name clearly posted.

Some of the 64-67 engines (64 and early 65 only? I don't remember) have the timing tab on the passenger side, requiring the timing to be marked differently, and the keyway is in a different location. I think otherwise the cranks are the same. I don't remember the details, so don't trust that.

SFI dampers have a cert that is required when running above certain speeds at the dragstrip. I'd say you can assume that they have tighter tolerances and more QA than other dampers.

Fluid dampers are a fancy tech. I honestly can't say if they're "better" in any way.

All "modern" Olds V8 (65 and later) other than the alignment difference should be the same, but re-balancing is generally a good idea if the motor is apart. My machinist had to drill a lot of material out of my Performance Products (bottom of the "name brand" list) counterbalance weight to get back to the stock specs.

All modern olds came from the factory external balanced. Some folks modify the rotating assembly enough to become internal balanced. The idea is to get rid of the big weights on the ends of the crank (on the damper and on the flexplate/flywheel) to reduce stress on the crank, thereby lasting for more runs at the strip. One of Old's claim to fame was the engines came from the factory with a better balance than most of the other GM brands. Rotating assembly re-balance is not required if using stock or near-stock components. The engine won't shake itself to pieces. Making big changes still may not be obvious. I file balancing under "really good idea", and not "critical" for a near-stock build.

The right answer for you depends on your goal. A cheap no-name damper will get the car on the road, and might even last a long time. SFI certified is a requirement if drag racing. A higher quality name-brand is more likely to last a good long time than a no-name.


RE: the OldsPower thread, 425's experience shows that most of the factory Olds components were pretty well balanced, and as long as he used near-stock pistons then it's all fine. The OP in that thread has the problem of the early 65 damper is completely different than the much more common later units.

J-(Chicago)

This is true. I have taken a 403 crank and bearings and tossed it right into a 350 without issue. I wouldn't have raced it that way however.

olds 307 and 403

I ran a 307 crank in a 403, even more extreme but put on a real balancer. It lasted 5 years but cooked the bearings revving it to 5500 rpm.