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There was a time when blue lay-out fluid was used, not necessarily to find out if both lugs were engaging but to fine the percentage of engagement or contact, 75% was good. Bolts with far less contact were were expected to improve but the belief was as the bolt contact improved the bolt would set back, causing an increase in head space. I have a Pratt and Whitney gage that measured beyond .0000, made by GE, I had no use for it in that configuration so I removed the electronic gage and installed a dial indicator, with a height of 11' it works better as a height gage when adjusted with standards, point being? The electronic gage would measure the finish and surface height, with any other gage the surface measured .000, with the P&W gage the surface looked as though it was rough cut.
For those that measure before and after, the amount of bolt set back can be determined, for those that can measure the effect a bolt has on head space can determine the amount of material material necessary to to get both lugs to make contact.
And If I need a bolt that increases or decreases head space there are two people I can call, the rest suggest trial and error.
F. Guffey
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