Main bolt difference

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cudamark

cudamark

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Has anyone tried to put a windage tray on a 273 and found the 340 main bolts too long to use? I don't remember having any problem in the past with 318's, 340's, and 360's, but, this particular block is giving me pause. I noticed the windage tray bolts were longer, than the stock 273 main bolts so, I checked the depth of the holes and there seemed to be enough room so that the bolts wouldn't bottom out. I then ran both a cutting tap and bottom tap into the block holes to clean them up. 3 of the 4 bolts will now tighten against the main caps, but. one won't. It's like it isn't tapped deep enough, or, at least as deep as the other 3 since they seem to work. I've run the taps as deep and tight as I dare several times to no avail. Has anyone run across this before? I guess I can just use some hardened washers under the heads of the main bolts, but, I don't know if that is going to hold the windage tray off too far, or have it interfere with something.

mainbolts.jpg
 
273's never came stock with windage trays. I wouldn't use multiple washers under those bolts. You could shorten the windage tray bolts slightly just make sure you have sufficient thread engagement. The Machinist Handbook can verify this for the given bolt/thread size. 65'
 
340/360 main caps are taller & beefier than 273/318 main caps. No sense in drilling/tapping any deeper than necessary in the respective blocks.
 
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