Boom ***** (out for awile)

[musclestang89]

Well took her out to K-dale tonight to see how she would run on some different tires. Well since I have 3.55 gears in it and I have been running with 28" tires wanted to see how 26's would do. First pass (and only pass :D), the car came out spinning alittle and went pretty good and then all of a sudden BOOM *****, car died and somthing hit the bottom end of the car. At the times I wasn't for sure what it was, but I did see the belts go flying.

Bill went and picked up my missing parts ;) , the ole haramonic (balancer and crank pulley) shearded right off the crank. I guess the belt was alittle tight :D. There goes that motor.

Its time for a a turbo now , not for sure on how long it will be till I'm up and running, but I'm thinking for awile. I will post up a pic later on tonight. Anbd more pics once we get it broken down to see if it damage anything else.

Brandon

[David Schwarz]

Hope you didn't blow your stuff up too bad Brandon. I hate when the race car isn't racing.

[musclestang89]

well its hurt pretty bad


here are a few pics, notice the last pic of the interior. It hit the car so hard it through the pod out of place. It also hurt the h-pipe and muffler and it did hit the tranny but not for sure if its hurt or not.



edit- why isn't the pics working? Am I going to have to get them hosted somewhere else?

[David Schwarz]

They may be too big? You might try posting them in your gallery.

Edit - don't forget to use the correct format (.jpg for example). I'm sure you did this, but sometimes easily overlooked.

[musclestang89]

ok here is a link to them from stangtuning. David I think there is just something wrong with it, this has happen to me before and to others trying to post a pic.

http://www.stangtuning.com/showthrea...12832post12832

[David Schwarz]

ok here is a link to them from stangtuning. David I think there is just something wrong with it, this has happen to me before and to others trying to post a pic.

Ouch! At least you're not hurt. The mechanical parts can always be repaired.

I'm going to post the pulley picture to see if it can be posted from my end. I'm curious to know why you couldn't post the photo...

[David Schwarz]

Try saving your photos without any spaces in the file name. If you must use a space, then insert one of_these. DOS never did like spaces.

[fanglemeister]

It may not have been a tight belt that did it in, that will cuase premature bearing failure, but a snapped crank is caused by over-flexing. I know of quite a few scca A-sedan racers who have snapped off their 50oz cranks in the exact same spot, those motors are only making @ 300hp but they rev the snot out of them for extended periods. The heavy 50oz imbalance causes the stock crank to flex an enormous amount, 28.8oz imbalance is the best bet for revvin' up a smallblock.

[root]

The heavy 50oz imbalance causes the stock crank to flex an enormous amount, 28.8oz imbalance is the best bet for revvin' up a smallblock.

Agreed 28 is better than 50, but for worry free revs - neutral is best...

Ian

[fanglemeister]

Neutral or zero external balance is not the best method for a 90 degree V8. Think about the word "balance"... 50oz and zero balance are at opposite extremes, one puts ALL the counterbalance weight on the outside, the other puts it ALL on the inside. Both being extremes, both can cause their own set of problems. The 28.8oz balance is the happy medium, it more or less splits the balance weight evenly between the inside and outside of the engine. It's a more balanced balance. <grin>

For a dedicated race engine you want the lightest reciprocating mass possible. Adding a bunch of heavy metal to the outside of the crank counterweights just to internalize the balance goes against this philosophy! And it costs alot more too. <wink>

[root]

First time I have heard anyone say that.....

To each their own :)

Ian

[5150 LX]

Agreed 28 is better than 50, but for worry free revs - neutral is best...

Ian

Agree with ya there Ian.......but cost is a factor. Those mallory slugs ain't cheap

[blueoval92]

Brandon, Man i'm sorry to hear of your troubles. Yes it's time for the big nasty Turbo! ;) Keep us posted on your progress.

[fanglemeister]

First time I have heard anyone say that.....

To each their own :)

Ian

Let me explain further before you write me off as just plain nuts :)

The imbalance weight has less to do with taking a load off the main bearings (that is the job of the crankshaft counterweights), and more to do with eliminating vibration. The purpose of the imbalance weight is to provide a rotating couple to cancel out the natural wobble of all 90 degree V8s. If you hang a 90 degree V8 from a single chain and run it, the block will wobble in a corkscrew pattern. A point on the front would travel in a circle and a point on the rear would travel in another circle displaced 180 deg out of phase from the front.

The fortunate thing for a V-8 is its natural rotating couple is in the same direction and frequency as the crankshaft. This means it can be balanced out with weights at the front and rear of the crank. BTW these weights are not exactly opposite the front and rear crankpins but are offset 18 degrees.

So take the crankshaft and hang a weight on the front, and another on the
rear, outside the crankcase. The farther in front and to the rear the weights are placed, the less weight is needed to make the same anti-wobble force, because weight placed further out has a greater moment arm.

Putting some of the imbalance weight outside the crankcase, you end up with a lighter rotating assembly, which equals greater horsepower. Running no weight on the outside is doable but you have to add a bunch of weight to the rotating assembly inside the crankcase to do it - it has a shorter moment arm. Some weight on the outside is better - takes alot less weight to cancel the wobble if it is out further from the middle of the crankshaft.

Too much weight on the outside is bad though, it puts too much strain on the crank snout at elevated rpms. I'm not really sure why Ford switched the 302s from 28.8 to 50 oz cranks to begin with, but if I had to guess I suppose the cranks could be made cheaper somehow.

[David Schwarz]

I had to read that twice Chris, but a very nice explanation. Your arguments certainly seem to favor a 28oz balance (like I would actually know).