Can an over-bored 390 big block be saved?

CN Spots · Feb 5, 2006

My father has offered to surrender the family truckster, a 1968 Ford F-100 Ranger with a 390 and T6 automatic. He put it in storage about ten years ago due to two overbored cylinders. This was the third time she was bored and she can't be bored no more.

How bad over-bored? When pop hammered in the pistons, they fell through to the floor. The truck is in excellent shape, sans paint, and has been in the family since the day he bought it new in '68. I know if I look hard enough I might find a used 390 block somewhere but I was wondering if the original mill could be saved? A friend mentioned re-sleeving it. Is this a viable option? I (or my brother) WILL restore this truck. I just need to know my options on this engine. Thanks. spots

rodbolt · Feb 5, 2006

Re: Can an over-bored 390 big block be saved?

depends that block can actually stand about a .080" overbore but pistons that size are tough to find, that block shares many parts and features of the 352,360,the FE 427 and the FE 429, memorie is getting a bit fuzzy but I belive there were two designs that displaced 429 cubic inches. resleeving is an option and not particularly expensive. as far as the pistons falling through I did not think they would clear the main saddles. may be time for some careful bore measurements.

Kenneth Brown · Feb 5, 2006

Re: Can an over-bored 390 big block be saved?

No 429's in the FE series. It was 352, 360,390,406,410,427, and 428. The was also a 361 and 391 which were heavy duty truck engines but otherwise the same as a 360/390. Rodbolt is correct in an 080 overbore in the FE's. I'll try to find my book and tell ya the bore sizes. Its by Pat Ganahal I bleieve, Ford Performance is the name. The FE series is one of the greatest ever built by Ford. They have full skirts and some are even 6 bolts(cross drilled to the skirts). They are extremely heavy and really benefit from an aluminum intake, that 100 pounds off the front feels like an extra 50 horses. Edelbrock just released a new set of heads for the FE's so they are still popular. My first truck was a 67 Ranger shortbed, I sure do miss her.

CN Spots · Feb 5, 2006

Re: Can an over-bored 390 big block be saved?

I thought the 427 was it's own monster altogether?... The engine already sports an Edelbrock intake and a holley 4 bbl carb and a set of headers. Pop had to wrap 'em cuz they were too close to the starter and kept burning it up. Prior to storage and before the engine was messed up he had a lot of the parts re-chromed, replaced and/or rebuilt. So for a project truck, this one's choice. Not sure if I could spring for alu. heads or not KB, but they sure would be nice. The ones that are on it were reworked before storage as well but they are the original cast iron heads and are heeaavy! Thanks guys. spots

rodbolt · Feb 5, 2006

Re: Can an over-bored 390 big block be saved?

I dont think the heads are as heavy as the intake

I was 17 the fist 390 I did a valve job on, the book said attach lifting hooks to intake and remove. they were serious

. but its a fairly solid engine. most used a bushed rod on the wristpin but that can be modified if needed, however in most street applications its fine. been a long long time since I played with fords.

Reel Poor · Feb 5, 2006

Re: Can an over-bored 390 big block be saved?

Originally posted by rodbolt: I dont think the heads are as heavy as the intake I was 17 the fist 390 I did a valve job on, the book said attach lifting hooks to intake and remove. they were serious .

You aint just a whistling Dixie.

ae708 · Feb 6, 2006

Re: Can an over-bored 390 big block be saved?

CN Spots... there was a SOHC 427 but it wasn't anything like the FE 427.

deputydawg · Feb 6, 2006

Re: Can an over-bored 390 big block be saved?

I am confused. Why would it have 2 overbored cylinders? Why not all 8? As far as the pistons falling through, how do you mean? Was the crank out and the piston slid free through the bottom of the cylinder? This would be either really really bad rings or the wrong pistons. Best solution, take the block and pistons to a good machine shop. They will tell you everything you need. Sleeving is a good option if you want to keep it original. The problem with boring too much is like was said here, hard to find pistons. More than that the cylinder walls get too thin and crack easy. But all 8 cylinders need to be the same bore size for it to run right.

magster65 · Feb 6, 2006

Re: Can an over-bored 390 big block be saved?

I think 'pistons fell to the floor' was a metaphor designating that 'she's toast!. I can hear it now... "What do you mean it was toast?" Not this kind

magster65 · Feb 6, 2006

Re: Can an over-bored 390 big block be saved?

Don't stare at the toast.

salty87 · Feb 6, 2006

Re: Can an over-bored 390 big block be saved?

but the toast is looking back at me

deputydawg · Feb 6, 2006

Re: Can an over-bored 390 big block be saved?

I see it! I see the face in the toast! It's Jimi Hendrix isn't it?!

Reel Poor · Feb 6, 2006

Re: Can an over-bored 390 big block be saved?

Originally posted by magster65: Don't stare at the toast.

How did you know???? Gotta agree with salty though.

Chief101 · Feb 6, 2006

Re: Can an over-bored 390 big block be saved?

Originally posted by deputydawg: I see it! I see the face in the toast! It's Jimi Hendrix isn't it?!

not even, it's Bluto

deputydawg · Feb 6, 2006

Re: Can an over-bored 390 big block be saved?

wearin a cowboy hat.

CN Spots · Feb 6, 2006

Re: Can an over-bored 390 big block be saved?

Kinda looks like Hank. Pop said they fell through... I asumed he ment all the way. They may have just been too loose in the cylinders. As far as how they got that way, the first place he took it to to be reworked, they put a 16 year old kid on it with a drill and a hone. Pop blew a gaskek and hauled it to some shop in Memphis which had the proper machines, but clearly, somebody was off their game. He measured the cylinders and confirmed that the two in the back on the driver's side were ruined. Not sure how they did it. spots

deputydawg · Feb 7, 2006

Re: Can an over-bored 390 big block be saved?

Check with a good machine shop and see if it can be sleaved, if you want to keep the block for original number match. I don't hear much about sleaving gas engines anymore, but it used to be done regularly. I think in todays throw away society it has become easier to just find another block.

CN Spots · Feb 7, 2006

Re: Can an over-bored 390 big block be saved?

If you know of somebody throwing away big blocks, give 'em my number.

It is somewhat of a "keep it original" thing but 1960s blocks are getting harder to find and I've always been told to avoid the 70 and up mills due to thinner metal. (true?) There were several 390s on ebay today so at least I know I've got options. spots

deputydawg · Feb 8, 2006

Re: Can an over-bored 390 big block be saved?

I just threw away a 390 a month or two ago. It was an early 60's, but had been frozen and cracked. I have never worried about the blocks in the 70's and up. I try to avoid cylinder heads due to smaller ports on some of them. As far as the block goes I don't think there is anything to avoid. Somone correct me if I a wrong.

heycods · Feb 9, 2006

Re: Can an over-bored 390 big block be saved?

427= bore 4.23 stroke 3.78 428= bore 4.13 stroke 3.98 390= bore 4.05 stroke 3.78 352= bore 4.00 stroke 3.50 Imformation out of my 1968 motors auto repair manual. I have a 390 in a 66 motorhome cab that junk if anybody needs one. Its gold painted like the pre 64s

Can an over-bored 390 big block be saved?

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