Building an '87 Evo basically stock (+.010) How critical or even necessary is it to use torque plates when boring jugs?

Thanks

 

Only way to do it no other way. As when you tq the cylinder is is under great pressure and it cause's the cylinder to be in the same shape as when it is tq'd and bolted on tothe engine case. IF you where to use a bore mic and measure the cylinder before installing the plate and then after you will see that is will move in size. You must use the plates to get a accurate bore on the cylinder.

 

THey also need to be torqued down in the same sequence as they would on the bike too.

 

Yes they do thanks Mega. I read some where that the amount of pressure that is induced into the cylinder is over 1000 psi of pressure?? The number seemed to be very large but I cannot for the life recall the exact number I looked but cannot recall where I saw that, do you know??

 

There is about 27 ways to look at the actual clamping force. The simplest is to use a number slightly less than the yeild strength of the fasenter. FI most standard applications use about 75% of the yeild strength. A stock TC cylinder stud is about 0.34 in diameter. That makes the area about 0.09 square inches. If you assume that the stud is grade 8 then the tensil strength is about 120,000 psi. OK F = 0.75 x 0.09 x 120,000 = 8171 lbs. You got 4 studs so the total clamping for is 32, 684 lbs.

Now check,, a typical good running motor can make about 1000 to 1500 peak preasure in the cylinder. A 95 ci TC would have 11.795 square inches of area. The pressure would be pushing at say somewhere between 12,000 lbs to 18,000 lbs.

Obviously you'd want the head hold down to be greater than the force produced under combustion so your head gaskets don't blow.

Bruce