To Sleeve , or NOT to sleeve , the age old question.

[jayb]

I wouldn't risk sleeving all the bores, you are still likely to weaken the top and have cracks up there after running.  Just sleeve the non-adjacent bores.  Also, for what it's worth, I had a .060" over 406 block that went to .080" over with no problems.  Some of those old blocks were really thick.  I wouldn't hesitate to bore it bigger if you have a sonic check done and you weren't going to put more than about 500 HP through it.

[MeanGene]

I have a sideoiler block that our old friend Hollis Franks was ready to take to the steel mill as he was pissed at it. He had spent a lot on it, lifter bores are bushed, and it has thick sleeves in all 8- too thick in my opinion. Bored into water, and decks compromised. It ran fine, but soon blew bubbles. He bought a std block from me, and brought the old one along "look at this!". Hate to give up on it, otherwise nice block. My buddy has a 672 ci 460 in his Pro Modified pulling truck, which has 1" thick deck plates and then sleeves- gotta admit, 460's are easier, just not as cool lol

[427John]

I wouldn't risk sleeving all the bores, you are still likely to weaken the top and have cracks up there after running.  Just sleeve the non-adjacent bores.  Also, for what it's worth, I had a .060" over 406 block that went to .080" over with no problems.  Some of those old blocks were really thick.  I wouldn't hesitate to bore it bigger if you have a sonic check done and you weren't going to put more than about 500 HP through it.

So is the weakness from the width of deck surface between the bores which would be ~ the same as a std 427 or is it due to the overbore making the transition from top of cylinder to bottom of deck surface too thin? I was reading something elsewhere that made it sound as if it was the distance between bore edges but maybe I was misunderstanding it.

[jayb]

427s have a different shape to the outside of the bore casting, which makes them stronger.  Kind of looks like a cloverleaf in cross section.  Makes them quite a bit stronger.  Your 406 doesn't have that shape, so if you bored it to a standard 427 bore size, it wouldn't be as strong as a 427 block.

[Falcon67]

Based on local prices here - and the complete lack of performance auto machine shops except for one maybe two - unless the block is a high value & rare piece, it's not economical to sleeve anything. The sleeve isn't the cost, it's the other setups and machine work that is 4~5 times the cost of just the part.  I'm a 351C guy and I'm slowly switching to 351W base blocks and aftermarket only. The stockers can't take the abuse and it's completely uneconomical now to fully prep an 50+ year old block.