[DeTomaso] NPC - Machine Shop Practices

[fordmachinist at gmail.com]

We will grind a crankshaft at time with the bearings installed in the block and the rods. There are time we see tolerance stack. 
But true, most shops will grind a shaft according to the spec size. Typically +/- .0004"
Performance may favor the low end of spec. But see do see that many aftermarket cranks are not that great.
Start miking the bearings. That starts to get scary. we will find .0002-.0004 difference in brands.

I worked for a production builder, and I bored blocks all day.
Didn't have any pistons in my hand. Just bored it to a nominal size plus maybe .0005" and that was it. Never saw an issue.

Neutral balance does not require balancer or flywheel. All the weight is on the inside. 
If the engine was a neutral balance design, you would balance the rotating assy first, then add the flywheel and balancer. If it is neutral balance, the balancer and flywheel could be balanced all by them self also.

Tim Meyer
TMeyer Inc.
www.tmeyerinc.com

Sent from my iPad

> On Nov 10, 2015, at 8:04 PM, Guido deTomaso <guido_detomaso at prodigy.net> wrote:
> 
>   Not sure why this is on my mind today, but:
>   It's common in my experience to provide a piston when a cylinder is
>   bored, so the bore provides a known clearance to that piston.
>   Does anyone do this with crankshafts, use the actual connecting rod
>   bearing ID and turn the crank to match?  By the time you get out the
>   plastigage, it's too late if the clearance isn't what you wanted.  But
>   I've never heard of anyone doing anything with a crankshaft other than
>   turn it down to some arbitrary diameter.
>   Similarly, from what I've observed on YouTube, it ought to be
>   technically possible to balance a crankshaft alone, then add flywheel
>   and balance it, then the pressure plate, then the harmonic balancer.
>   This would make all those bolt-on items "neutrally balanced" and they
>   could be replaced or swapped from engine to engine.
>   What I suspect usually happens instead is, all the parts are bolted
>   together and balanced in one shot, making a set which cannot be broken
>   without upsetting the achieved balance.
>   So, if I asked that a crank be turned to match the rod bearings, or
>   that the bottom end NOT be turned into a matched set, am I likely to be
>   shown the door?
>   Thanks,
>   GD
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