I would check on the torque required to get that bolt into its working range. If it is over about 60 pounds, I would use a lower strength bolt that can be torqued into its working range at 65 pounds or less. The cast iron holes will not stand all that much in the way of torque. Its kind of a fine thread unlike good old American engine blocks with big diameter course threads.

 

Real SAE grade 5 bolts can be bent sharply over 90 degrees without failing. Grade 8 bolts, while capable of a higher ultimate loading (tensile) seldom make it to 90 degrees without failing. They are much better in double shear than the grade 5 but this is not it. My driver built up quite a store of data on this subject while going through a half million dollars worth of bodywork. Even with grade 5 or whatever that is in metric, torqued into their working range, you could pick the plane up and shake it for 100 years by the reduction unit and no fastener failures would occur.

 

Whenever we had a Cosworth apart we would change the rod bolts. They were pricey but the owner wanted new bolts each time. I suspect that he went past the red line every time he got into the car. The Cosworth rep came to Mid Ohio once and found the owner. He wanted to know what we were doing to the bolts that we needed so many. The rods were designed around the bolts. Deep enough to get enough threads to get the bolt into its working range. Then center to center distance and so on. He pointed out that they could tear the big end off of the rod without failing the cap or the bolts. So if the rod cap was still on the rod, it was fine. So we quit changing rod bolts. They had dimples on each end and you torque them with a special dial indicator rig in place, until they stretch .0035" and that was it. Not by torque. By stretch. We never lost a Cosworth engine.

 

The bolt choice is limited by the cast iron holes. Perhaps studs for some of the application.

 

Lynn E. Hanover

 

 

 

 

In a message dated 5/7/2008 10:42:50 AM Pacific Daylight Time, echristley@nc.rr.com writes: