Max. bore w/ liner

[ChrisS]

What is the maximum that you can bore a 1275 block that has liners? I have a block with a deep score that will require 0.060" overbore but the cylinders have the liners. Will the liner move or warp at this overbore size. Thanks

 

[jollyroger]

If the sleeves are installed correctly you should have no problem replacing it. The proper way to install a sleeve is to overbore the cylinder leaving a shelf at the bottom for the sleeve to rest on. then the sleeve is pressed in to rest against the shoulder. The top of the sleeve is then milled even with the deck. A good machinist can cut the old sleeve out and just press in a new sleeve. Most sleeves I see are installed wrong. the machist will bore all the way through the length of the cylinder and press the sleeve in leaving a bit hanging out in the crank case. Done this way the sleeve CAN and will slide to and fro at the worst possible time.(well there is no good time)

 

[aeronca65t]

I've seen a couple of 1380 engines that started as 1275s.

I *think* the boring has to be done off-center (of the original bores) to make this work.

 

[ChrisS]

Thanks for the replies, I think I found the answer. The machine shop was comfortable with 0.020", Davis Anton / APT said no more than 0.030", and downward movement of the sleeve without a lower lip is a real possibility, as Jolly stated, and Vizard’s books makes reference to A plus block in the early 80's that were factory sleeved and only really good for 0.020" or 0.040" for moderate performance engines but not race. So Split the difference and call it 0.030". As far as the 1380 borings, that will completely remove the sleeve and is what I will end up doing with this block later. I stripped another block today that doesn't have liners and it will go to the machine shop Monday.