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Discussion Starter #1
Does anyone have a sbc crank laying around? I am going to drill my 283 crank for a harmonic balancer bolt and and am curious how deep I need to drill the snout. I haven't been able to find this info online. if someone could tell me the depth I would be grateful:hurray:
Thanks,
Jeff.
 

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I want to say 2-1/4" to 2-1/2" or maybe even 3" deep.

Take a 7/16" x UNF bottom tap for a SB or a 1/2" x UNF tap for a BB and tap away.

pdq67
 

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Not really true b/c in a lot of cases, the 1st 1/2" of threads have been wallowed out.

If you can't hunt up a bottom tap, then very slowly remove say the 1st 5 or 6(?) threads of a regular tap and be sure to NOT over-heat it or you will ruin it!

pdq67
 

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Do not forget to account for pulley depth. For example a billet aluminum pulley will be thicker than a stock metal pulley, thus the bolt length will need to be longer to compensate for thicker pulley. If your 1st few threads are stripped then that will require an even longer bolt to ensure you have enuff threads to hold with.
 

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Discussion Starter #7
Just went out and measured a stock 350 crank and it is 1 1/2".
Thanks, that is what I was looking for. But at this point my machinist suggests just leaving it as-is since I found a nos crank (the nose of it isn't all galled up from having balancers pressed on and pulled off, that's why I didn't want to press my new balancer on to make a measurement). He says and I tend to agree that the bolt is more for installation than to secure the crank. I think my last crank had been "polished up" by the previous machinist where the balancer fits and may have been a little undersized. The balancer slipped/rotated and ended up ruining it and the crank. It never did come off though (lucky!) I have a new balancer too and since this is only a 5,500 rpm engine all should be good.
 
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