Converting 40 sleeve block to 90 sleeves

John Ayres · Dec 20, 2013

I have a 8N block that someone ran without the sleeves in it. The bottom line is the cylinders are uneven and after an attempt to hone the walls and put 45 sleeves in the sleeves were uneven and the lip broke off. I am resigned to trying to bore out the cylinders and use 90 sleeves. Were the blocks the same for the 40 and 90 sleeved motors and can this be done? Is it unusual to have someone cut the lip the sleeve seats in at the top.I am concerned that there is not enough meat on the block to re bore this and not have a problem? Looking for knowledge and advice on this topic. Thanks, John Ayres

old · Dec 20, 2013

If you ask this down in the 9N/2N/8N forum you will get a lot more answer and most likely better ones

Joe Scribner · Dec 20, 2013

I've never done this repair myself but have done a lot of reading on both boards on the subject. I believe your engine block with the thin-wall sleeves can be be bored out to accept the thicker sleeves with no problems at all. A competent engine rebuilding shop can bore it out to fit the new sleeves, it's not something you can do yourself unless you're an engine rebuilder.

Earl-IL · Dec 20, 2013

I had a automotive machine shop for 40 plus yrs. We did many of the Fords. Caution, is to find a shop that has the experience. The proper fit of the thicker sleeve and the proper cutting of the counter bore, done right will make you a sweet running engine. Not every one can do you a perfect valve job. Email is open if you need more info. Earl

Dean · Dec 20, 2013

You can bore the block to accept the .090 cast iron sleeves. Use 3 ring pistons if you do this.

I prefer replacing the .040 steel sleeves with the same early OEM sleeves but most machine shops do not want to do this because it is easy to ruin the sleeves upon installation if not done properly. You can use early 4 ring pistons if you use the steel sleeves.

Dean

Paul in MN · Dec 20, 2013

I've had 3 blocks bored from the 040 to the 090 sleeve. The machinist is familiar with the N engines and has done many dozens of such jobs. One of my blocks had a split wall in the 040 bore, and he bored it 125 to take a heavier sleeve. He felt that that motor would be good for another 30 or 40 years.

At the Ford tractor dealer shop, every thinwall engine they rebuilt was bored to accept the 090 sleeves. They probably did hundreds of jobs.

Paul in MN

Converting 40 sleeve block to 90 sleeves

John Ayres

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old

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Joe Scribner

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Earl-IL

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Dean

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Paul in MN

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