nelapse

iTrader: (17)

A few days ago... I was trying to find TDC and by turning the crank the bolt fell out. Looking at the bolt it was clean and perfectly intact. Obviously the previous owner did not locktite it. The harmonic balance came off by hand....
(thank god I found this before I went driving.)

So I installed it back on, then all of a sudden I start shredding belts like crazy.
Turns out, my crank pulley is too far towards the engine..

At first I thought I installed the harmonic balancer too far in... which in my mind was impossible. Then it all occured to me that maybe the previous owner is using the wrong kind of crank pulley. Which in theory could explain the harmonic balancer bolt coming out. Knowing that the pulley was the wrong one he perhaps compensated by not fully seating the balancer?

So I used an old think balancer washer and put it behind the crank pulley and used 4 washers a piece on the back of all the crank pulley bolts. Now she has stopped throwing belts off and ripping them apart.

THIS IS A TEMP FIX. I need to find out if there are different size crank pulleys for serpentine? Anyone have any ideas if some serpentine pulleys are different?

TransAM Joe

iTrader: (6)

I've never seen different size stock crank pulleys, but aftermarket underdrive, yes. But only difference in diameter not depth. Maybe the previous owner thought it was a good idea to go to the junk yard and find a smaller pulley instead of buying the correct one. I have a stock 1988 350 TPI crank pulley if interested.

nelapse

iTrader: (17)

can you or anyone else, measure the diameter of a stock serp crank pulley, then measure the thickness from outer lip to inner lip.

TransAM Joe

iTrader: (6)

8" in diameter and 3 1/4" deep including the damper side lip.

nelapse

iTrader: (17)

can you take a pic of the back side....?
It is so weird... my car is suppose to take a 480k6 but takes a 460k6 the rear of my pulley is flat

TransAM Joe

iTrader: (6)

yea it have to be tomorrow, got to put the little ones to bed. Sounds llke you got the wrong pulley.

nelapse

iTrader: (17)

thanks...

Damon

You're right- you can't get the balancer on too far. It goes in until it hits the face of the crank pulley- clunk, done. And I don't think GM had changed the distance from the back of the balancer to it's face in decades- maybe never. I agree, it sounds like maybe just the wrong crank pulley. Factory crank pulleys on 3rd gen f-bodies sit the belt pertty far forward of the balancer face- don't have one laying around or I'd measure it for you.

TransAM Joe

iTrader: (6)

here are some pics, on the left is the stock crank pulley and on the right is the march #4405 underdrive crank pulley. Notice the rear lip on both and the significant diameter diff., but depth remains the same at 3 1/4". Hope this helps.

nelapse

iTrader: (17)

My pulley does not have that small lip on the end of the rear. I will measure the pulley in about an hour

nelapse

iTrader: (17)

My pulley is 6" in diameter and 3" from front to back.
Nice that it is underdrive.... sucks that it is not right to being a safe width.
----------
Summit sells an under drive pulley for $50.00 comes with alternator pulley too... which is alot cheaper than buying a new engine if my temp fix fails...

TransAM Joe

iTrader: (6)

yes the underdrive set for $50 at summit March #4405 is one I have pictured above minus the alt. pulley, good quality for the price. The lip on the back of the pulley actually rests inside the damper and the body of the pulley sits flush against the damper, which it doesn't matter if yours has the lip or not. So take off about 1/8" for the lip when measuring the pulley and it's very close to your 3". It was slow today so I did mock setup of a crank and damper to see if you can install the damper too far and you can by about a 1/4" which sounds like about the amount you are off. The rule of thumb when installing the damper is put it on and mock up the water pump with pulley and align it with the crank pulley to know how far to put the damper on. All the damper has to do is ride inside the seal of the timing cover and could be different for each application based on the pulley used, just seating the damper against the crank shoulder is not a given.

nelapse

iTrader: (17)

So you are saying that I shouldn't fully seat the balancer against the crank if it throws my pulley alignment off? I thought you would want to fully seat it to make sure that your harmonic balancer bolt gets as many threads as possible.

Damon

No no no. Always put the balancer on all the way. Then get the right pulley.

nelapse

iTrader: (17)

Perhaps, I have the wrong balancer or something... if there is nothing wrong with the width of my current pulley... since TA joe says the lip is mated in the balancer then maybe the problem lies else where.

I will try and measure it again today.

Damon

If your current pulley doesn't have that "centering lip" to positively locate it on the front of the balancer then it's probably a pulley problem. Every SBC crank pulley I have ever seen has that lip. Stock, aftermarket, they all have it.

nelapse

iTrader: (17)

turns out that the pulley is really like 2 3/4" deep... so what the heck did this pulley come off of? Corvette maybe....? some truck?

TransAM Joe

iTrader: (6)

didn't mean to confuse you, yes always fully seat the damper, it's just some damper crank combos depending on how machined in my experience can fully seat in different locations, say 1/8 to 1/4". If you are at 2 3/4" that is your problem. If you want you are more than welcome to my stock pulley for $10 shipped to you, nothing wrong with it just using the march underdrive.

nelapse

iTrader: (17)

Let me sleep on it. Now would be a good oportunity to get an underdrive pulley. If I get the stock its $10 and $20 for a new belt. So I might as well the underdrive I guess.... How wide is the underdrive diameter. 6"?

Vader

It could be a Corvette damper (short water pump) or something else. Either way, something about it isn't right. If you don't bolt it on and install it fully, you risk having it wobble, damage the crank snout (if it hasn't already) and falling/breaking off. The Poly-V sheave that drives the accessorys might be in het wrong place, but hte damper must be bolted tight against the timing sprocket/crank nose shoulder.

88fbird

Damn Cale, I'm sorry I didn't see this post sooner. I got that pulley on Ebay along time ago. It was supposed to be for a Firebird/Camaro 82-92. The crank pulley and alt pulley were both changed. They both came in the same kit. When I put them on the crank the inner lip prevented the pulley from going on the balancer all the way. At the time I didn't have much time to mess with it, so I took off the lip. The balancer matched up fine with the other pullies that way. Definately not perfect, but it worked pretty good. I had those pullies just like that on 3 different engines in that car w/no problems. The balancer was changed with the engine the last time and is different from the one I modded it for, so a new one might fit just fine on that one. Like I said, I'm sorry you had a problem with it, but I did it so long ago with no problems that I forgot to mention it to you! Let me know if you need anymore info.
Tim

nelapse

iTrader: (17)

noworries, I have it taken care of perfectly. I have it temporarily spaced until I buy the B&M 3 piece aluminum kit. This is the kit I have decided on. Besides, if nothing ever goes wrong then I get worried.