How tight should big end bolts be in the conrod?

[Albie 0]

I'm rebuilding the bottom end of the 9A and putting in new big end bolts like a good boy. They look exactly the same as the ones I have taken out but I can't get the new ones into the conrods. I don't mean just the knurled final bit just beneath the head, I mean the two stepped shoulders just after the thread. That doesn't give me any thread poking through the bearing cap to wind them home with the new nut.

 

So can someone tell me just how tight these should be and, assuming these are right, what is the best way to get them in?

[VEEDUBBED 0]

Are the rods out of the engine?,if they are try to find an old piston gungeon pin and fit it over the new bolt,then put the rod into a large vice and slowly close the vise untill the bolt is pushed into position,heating the rod end with a blow torch expands the rod,helping the bolt to seat.

If the rods are still inside the mill you could do the same thing using small metal spacers or lots of steel washers(old valver headbolt washers are ideal,after cutting the buggers of the bolts using an angle grinder).

[Albie 0]

Thanks once again for the advice Veedubbed. It is really just a case of worrying about whether this is the normal state of affairs or whether there is something really wrong. I have done this job many times before, but never with stretch bolts in this location, so I'm used to these bolts only needing a mild push home or going in far enough to use the cap to finish the job as they are tightened home.

 

If they are normally this tight, winding them in seemed to me to be a sensible thing to do. I was worried as to whether this would need so much pressure that the bolts actually stretched, knowing that this is what they were made to do. Now you have confirmed it isn't too unusual, I'll find something to use as a sleeve and try pulling them in using one of the old nuts.

[Albie 0]

Just to round off here. I used a couple of exhaust manifold to downpipe nuts as spacers over the new bolts and wound them in with their own old nuts. I made sure to use a torque wrench set to 22lb, the first stage in the tightening sequence, so I could check that they didn't go over and begin to stretch at any time. It was a piece of proverbial and in about 10 minutes they were all in and I could finish the bottom end.

 

Thanks for the advice.