FE Overbore
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FE Overbore
How far can the typical 352/360/390 blocks be bored?
If I can locate one, I will be using a 3.98" stroke crank to make a 410 in3 motor, 3.78" stroke crank if not avarilable. I have a '66 352 standrard (4.00"); a +.030"(4.080") '72 360; and a '70 +.030" (4.080") 390 marked with mirrored "105". Which would be the best canidate for a rebuild/overbore that would not cause over heating problems?
Is 4.110" (360/390 +.060" over bore) the limint, or will they go to 4.130" (410/428 std), without over heating?
If I can locate one, I will be using a 3.98" stroke crank to make a 410 in3 motor, 3.78" stroke crank if not avarilable. I have a '66 352 standrard (4.00"); a +.030"(4.080") '72 360; and a '70 +.030" (4.080") 390 marked with mirrored "105". Which would be the best canidate for a rebuild/overbore that would not cause over heating problems?
Is 4.110" (360/390 +.060" over bore) the limint, or will they go to 4.130" (410/428 std), without over heating?
Fleet Mechanic
Joined: Jul 1999
Posts: 1,360
Likes: 1
From: Iowa
I wouldn't bore it out any more than what's necessary to clean up the cylinders for proper ring sealing.
If you do feel the need to hog out your cylinders, then pay a shop to sonic check the cylinder walls so you know exactly how much wall you have. Nothing worse than breaking into the water jacket with a .040 overbore.
If you want inches, buy a crank.
If you do feel the need to hog out your cylinders, then pay a shop to sonic check the cylinder walls so you know exactly how much wall you have. Nothing worse than breaking into the water jacket with a .040 overbore.
If you want inches, buy a crank.
Lead Driver
Joined: Apr 2001
Posts: 6,175
Likes: 21
From: Texas
It depends on what block he uses!
I like the Mirrored 105 block if its good at .030 over. It will probably go another .030 over (.060 total) if needed and might even go a total .080 over to make a 4.13" bore. See if you can get a rough idea of what it would take to clean up the bores then have it inspected at a machine shop.
my 2 cents
I like the Mirrored 105 block if its good at .030 over. It will probably go another .030 over (.060 total) if needed and might even go a total .080 over to make a 4.13" bore. See if you can get a rough idea of what it would take to clean up the bores then have it inspected at a machine shop.
my 2 cents
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Elder User
Joined: Jul 2002
Posts: 510
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From: Charlotte
You won't get better advice than whats given above there.
My 390 was recently rebuilt and safely bored out another .030 to 402.
My 390 was recently rebuilt and safely bored out another .030 to 402.
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Thanks guys, Sounds like to me the '66 352 would be find going to a std 390 bore (4.05"); the '70 +.030" 390 mirrored 105 might be ok at +.060" and questionable at +.080". Hope to pull one of these down this summer/fall for rebuild. Will try to locate someone in the Atlanta area that can do a sonic check on the walls before boring.
Question? When FORD made the 428's, did they use the same castings as the 352/360/390? If so, maybe the smaller units will be safe to inch up. Or is the 428's a unique block, and has larger capacity? Can only hope that FORD took the easy route, and had extra thick walls in the smaller units.
Question? When FORD made the 428's, did they use the same castings as the 352/360/390? If so, maybe the smaller units will be safe to inch up. Or is the 428's a unique block, and has larger capacity? Can only hope that FORD took the easy route, and had extra thick walls in the smaller units.
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
A lot of the mirror 105 blocks were cast with 428 cylinder wall cores. This means you've got a lot of beef there for overboring. This is definately the block I'd use.
I'd limit the overbore to .060" without sonic checking though. You dont know how bad it's core shifted without checking it. With a sonic check, go with the results. Look at the wall thicknesses, and bore accordingly. I'd leave at least .2" wall thickness after boring.
I'd limit the overbore to .060" without sonic checking though. You dont know how bad it's core shifted without checking it. With a sonic check, go with the results. Look at the wall thicknesses, and bore accordingly. I'd leave at least .2" wall thickness after boring.
Needsmorecoffee.
Joined: Oct 2004
Posts: 3,624
Likes: 2
From: CT
Try Southern Automotive. www.southernautomotiveengines.com They are south of Atlanta. Bill has quite a collection of FE engine parts you can oogle over besides. They can sonic the block and any do machine work if you need it. Do a search here for the "drill bit test". That's a easy way to check what cyl wall cores your blocks were cast with before you have them sonic mapped. This way you'll know if one of the blocks is a good 4.13 bore candidate before hand. Just a thought.....
G.
G.
