FE question

I know this is not a FE forum but there are a lot of engine builders on here so here it goes, at the machine shop today and the machinist don't know how much he can bore a 1968 390 block safe, its already .060 and still need's .010 more so I told him that I would ask if it could be bored .080 like the 385 block can, its for a street build going back into the 1968 F100 with a small cam, intake and headers, so if you can help than thanks in advance.

butterbean wrote:I know this is not a FE forum but there are a lot of engine builders on here so here it goes, at the machine shop today and the machinist don't know how much he can bore a 1968 390 block safe, its already .060 and still need's .010 more so I told him that I would ask if it could be bored .080 like the 385 block can, its for a street build going back into the 1968 F100 with a small cam, intake and headers, so if you can help than thanks in advance.

Have it sonic checked first some 390 blocks will go .130 over bore and some do good to go .060. Good luck

Like Whitefield said have a sonic test done .The most common block for .080 over is a d3-d4 block .On the front where an older block has 352 it will have a reverse 105 .Commonly called in the fe community mirror 105 .Maybe you want to install a 428 crank in this block to build a 428 .Pretty cool build but FEs tend to not have thick cyl. bores .070 pistons aren't common but possible with a custom piston .This will stir the Fe experts up I had one of those mirror 105 blocks that had been bored .080 .I had a sonic test done to it and the thinnest spot was .157 .Most were thicker but that was the thinnest spot .I sold it to a fellow in Fla. he had that block bore another .060 ( he already had the pistons ).So that made the thinnest cly..127 I saw his mustang run a 6.26 .Sometimes with the fe it is just how lucky for are.Have a reputable shop do your sonic test maybe you will be lucky too.Doug8)

manofmerc wrote:Like Whitefield said have a sonic test done .The most common block for .080 over is a d3-d4 block .On the front where an older block has 352 it will have a reverse 105 .Commonly called in the fe community mirror 105 .Maybe you want to install a 428 crank in this block to build a 428 .Pretty cool build but FEs tend to not have thick cyl. bores .070 pistons aren't common but possible with a custom piston .This will stir the Fe experts up I had one of those mirror 105 blocks that had been bored .080 .I had a sonic test done to it and the thinnest spot was .157 .Most were  thicker but that was the thinnest spot .I sold it to a fellow in Fla. he had that block bore another .060 ( he already had the pistons ).So that made the thinnest cly..127 I saw his mustang run a 6.26 .Sometimes with the fe it is just how lucky for are.Have a reputable shop do your sonic test maybe you will be lucky too.Doug8)  

I just recently sonic tested 8 FE blocks for a customer and ALL of the 390's would be under .070 thick if bored to 428 size. They were assorted blocks including a few D4's/105's. Supposedly some of those that were used for FT service were cast using the 428 water cores but we didn't find any in this customer's stash.

thanks to everyone for the replies, I'll pass on the info