This might be of interest to some folk on the list.
A while ago I was looking at the six cylinder engine rod bolts and
found they are not available in high strength steel and the only
options appear to be used original or lucky-dip replacements of
unknown origin. I looked at several bolts from other engines and with
the help of ARP tech support settled on 454 Chev part number 135-6401
which are 1/16" too short and 0.0075" bigger diameter. This increases
the torque from stock 50lbft to 80lbft or approx 60% higher clamping
force as well as providing press-fit location of the cap.
The caps needed spot facing to account for the reduced length which I
achieved with a 3/4" counterbore off Ebay
https://www.ebay.com/itm/253113534458 and a 7/16" pilot
https://www.ebay.com/itm/370673620820 Although the counterbore is for
a Morse Taper, it works just fine in a regular drill chuck.
I used a low cost adjustable HSS hand reamer
http://tradetools.co.nz/products/5620400 and increased the cutting
diameter gradually until the caps fit snugly onto the 'wave' section
of the bolts. There is so much variation in the stock bolt holes that
some needed a lot of reaming and some none. Bolts were installed using
a brass hammer since I don't have a press.
Some pics attached of the semi-finished rod, it has had the clamping
faces machined 0.005" each and now goes back to the engine shop for
resizing the tunnel. There are two ways of resizing, using a hone
which is rather sloppy or using a machine which is far more accurate
as it doesn't increase the sideways diameter. The bolt holes are
extremely close to the bearing tunnel so honing isn't a good option.
Cheers,
Andy.
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