Block Sizes

[Bob G]

Does Anyone Know The Exact Size Of The Main Bearing Bores In The Block For Line Honing ?
Thanks Bob

[A26B]

Bob,
This is the best info I have. It is taken from OEM engine drawings for the 375hp engine. I cannot say if there were revisions later, but you should be able to tell by reassembling the lower crankcase to the cylinder case and measuring the bores. If undamaged journal bores fall in this tolerance range, I would feel comfortable with the dimensions given here.
Jerry

[lbszr]

Originally Posted by A26B

Bob,
This is the best info I have. It is taken from OEM engine drawings for the 375hp engine. I cannot say if there were revisions later, but you should be able to tell by reassembling the lower crankcase to the cylinder case and measuring the bores. If undamaged journal bores fall in this tolerance range, I would feel comfortable with the dimensions given here.
Jerry

Mine measured 2.9428 1,2,3,4 and 2.9417 on 5 so my .003 more could be measuring technique or stretch or they didn't hit the mark.

[A26B]

I thought the tolerance in the drawing was pretty generous (0.01mm). Would have thought it would have been tighter than that.

74.56mm = 2.9354"
74.66mm = 2.9394"
0.01mm = 0.0040"

Since you're calling out dimensions in ten-thousandths, I think it's safe to assume your technique it pretty darned good and used something better than dial calipers.

How did your bearing wear pattern look?

[lbszr]

Originally Posted by A26B

I thought the tolerance in the drawing was pretty generous (0.01mm). Would have thought it would have been tighter than that.

74.56mm = 2.9354"
74.66mm = 2.9394"
0.01mm = 0.0040"

Since you're calling out dimensions in ten-thousandths, I think it's safe to assume your technique it pretty darned good and used something better than dial calipers.

How did your bearing wear pattern look?

If I remember right, #1 showed the most wear on the top half which gm manual said that was normal and all the others showed signs on the lower half but all were minimal and plastigaged good within limits, the other halfs basically showed no wear.


I used a inside micrometer but didn't trust it so then measured the inside micrometer with outside micrometer, don't have a bore micrometer.