390 to 428
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
Kind of. The bore of the 428 is .080" bigger than the 390. What needs to be done depends on your 390. If it's a truck 390, you just put a 428 crank in it and it's a 410. You do need to bore it oversize to remove the ridge, since the piston and rings will travel farther up the cylinder with the longer stroke 428 crank. This will break rings and ring lands if the ridge is not removed. .030" oversize = 416ci, .060" = 422ci, .080" = 428ci. I'd just take it .030" oversize to leave more potential rebuilds in the block. .080" oversize to make it a true 428 is really pushing it, and you'd have to check the cylinder wall thickness. Realistically, you'd be hard pressed to notice those last few cubic inches anyway.
You'd also have to get it balanced too.
You'd also have to get it balanced too.
Postmaster
Joined: Nov 2002
Posts: 3,447
Likes: 1
From: Littleton, CO
The 428 was externally balanced at the flywheel/flexplate. If you have either that was associated with the crank, then balancing isn't too much of an issue. It is however always a great idea.
--Mike
--Mike
Lead Driver
Joined: Apr 2001
Posts: 6,175
Likes: 21
From: Texas
All FEs except the 428 are internally balanced. The 428 crank will need to be internally balanced by a mchine shop or use the 428 flex-plate or flywheel.
You can also go aftermarket with your crank and get 428 and bigger, and just bore enough to clean things up.
You can also go aftermarket with your crank and get 428 and bigger, and just bore enough to clean things up.
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
Yes, you definately need to balance it. Keep the 390 flywheel / flexplate but have it internally balanced. That's not the reason to balance it though, it could work just fine with a 428 flywheel / flexplate.
The big reason is that the rods from the 390 wont be balanced anywhere close to match the 428 crank. This WILL cause problems. If it was a stock rebuild with .030" oversize pistons I wouldn't worry about it, but since you're changing out the crank that makes a big difference.
The big reason is that the rods from the 390 wont be balanced anywhere close to match the 428 crank. This WILL cause problems. If it was a stock rebuild with .030" oversize pistons I wouldn't worry about it, but since you're changing out the crank that makes a big difference.
Needsmorecoffee.
Joined: Oct 2004
Posts: 3,624
Likes: 2
From: CT
BTW the 410 is also externally balanced. I agree to just cleanup the bore to the next size leaving you some room to grow later on. If your just curious about the block you can knock out the block freeze plugs and gap the distance between the walls. Using drill bits a 17/64" drill bit shank should be a snug fit between the walls for 390 wall cores. A 13/64" bit snugly fits 428 wall cores. This is a crude (cheap) but effective (free) way to tell which wall cores are in your block. If it has the thicker 428 cores you can then have the block sonic checked for actual thickness and core shift to determine if a 4.13 bore is doable. I've seen some strange block castings and you never know till you check as it's possible. G.
Trending Topics
Thread Starter
|
Junior User
Joined: Aug 2004
Posts: 81
Likes: 0
From: Huntsville, AL
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
!["Beemer Nut"'s Avatar](data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 50 50'><circle class='avatar-circle-default' fill='%23bc5285' cx='25px' cy='25px' r='20px'></circle><text class='avatar-text-default' x='49%' y='53%' fill='white' text-anchor='middle' alignment-baseline='middle'>"</text></svg>)