Think the normal rountine is to deck, then bore. The machine shop certainly would know the procedure.
LS vs 406
- Thread starter albertaborn
- Start date
If you are gonna do the 400 then my advice is to only go .020 over. Pistons in that size might be harder to find but worth it.
Would be best to have the block sonic tested. Then go with the minimum bore needed to clean up the cylinder walls.
Why is it such a big deal with the 400 blocks. They have been bored .030 overs so many times it standard talk to say 406. There a lot running .040 and .060 over with not a lot of problems. I think every motor has it limits if pushed over the edge. I have only had one come in the shop with a cracked cylinder and that was because the stupid kit was running the cheapest 87 fuel instead of running the 91 like he should have done with the compression of the motor. I know the circle track guys lost a lot of the motors by just being stupid like running them out of oil or a hole in the radiator and running hot till they stopped, just stupid thing like that. From the factory the moved the land barges from the 1970-1980 in cars trucks motor homes and everything inbetween. Just build it right and stay away from the stupid stuff.
I personally don't see much reason to overbore a cylinder just for the sake of a few more cubic inches.
It would be had to find a stock 400 that would not need to be bored. Might find one in a motor home or a boat. Most were used up to some extent when they were pulled.
Right I'm speaking of a bore that would clean up at 15-20 thousandths and they decide to go 60 thousandths to get a few more cubic inches. It will still work but I'd rather do something like that to an aftermarket block vs stock. It's more personal preference.
The reason I would bore is because my machinist said there was 7 thousand wear. I never thought of just go in .20 over.... that actually makes pretty good sense. Buys me another rebuild down the road. At 7 thousand what should I bore minimum
Also doesn't seem to be aNY guys in my town that sonic check. Would have to drive a couple hrs. I see the benefit but am rolling the dice on that one
Sonic check would be nice if you were going .060 for the reason the block was all ready a .030 and needed to be cleaned up. I haven't found a lot of pistons in the .020 range but a LOT of .030 so you can set your compression a lot better with a bigger selection of pistons. What ever size you bore the cylinder you are only taking half the bore out of the cylinder sides. .030 over and you are taking .015 of metal out.
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