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Discussion Starter #1 (Edited)
Please help clarify for me. A friend gave me a "390" long block to strip and build my stroked 390 out of so I would not have to use my matching numbers block original to my '67. Upon dismantling it, I checked the stroke and bore and sure enough, it is a 352,(3.5" stroke, 4.00 bore) not a 390. Did they use the exact same block? (date code shows Dec 15, 1965 cast) Can I bore this out to .030 over a standard 4.050 390 cid (4.080) bore to safely achieve what I want?

I have searched this site for this information, but guess I missed the exact "Yes it is" or "No it is NOT" the same block statement.

I appreciate the help.

Tommy
 

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Hi Sifu-Sitaigung,

I'm a lot like you, kind of new to the FE engines within the last 2 years. I've got three of these to build up ('66 352, '66 390, and a '68 390) and I'll be happy to share with you what I've learned from a handful of books I read to other articles.

The short answer is maybe, the FE blocks suffered from "core shift" and so the best way to determine if your 352 can be bored to a 390 (0.05" over) is to have it ultrasonically tested for the cylinder wall thickness. That's the safest way to see if the block can withstand it.

For the little time and money it takes to have it done is a huge piece of mind in the long run, especially if you're going to spend $$$ on a build up.

Cheers,

DesertXL
 

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Discussion Starter #4
Thanks for the reply.

Well, I am looking to take it to 4.080 to support a 445 cid stroker kit. So can this thing handle that? Or do I just need to use my original block?
 

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It's the same block. In Detroit they just grabbed the block off the hook and bored it, some 352, some 390, nobody ever did a sonic test. You should do the same thing. Just bore it out and don't look back.

Same with decking, line honing, torque plates, testosterone therapy, perpetual motion machines, time shares and ugly women make better wives. Forgetaboutit. Just a bunch of theoretical hogwash from people wanting to share your wallet.
 

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FWIW, I bored my 352 block to 390 (4.000 to 4.050) and didn't sonic check it. Doesn't overheat now it's a 390, and all worked out fine. However, I'd be hesitant to go to 4.080. If I ever rebuild mine, I'll be sure to sonic test it before I have it bored ay larger, as technically it's at 50thou right now. A sonic check costs all of $200 here in Australia, so I'm sure it would be cheaper in the US to do the same.

I'd get it sonic'd. Better to spend a little up front than to have a disaster later on.
 

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Discussion Starter #8
Thanks to everyone for the quick replies. I will drop it off at the machine shop and have them dip, flux, and tell me if they see enough meat to do what I want to do. I'll have well over $10000 in this engine when it's done. From the Edel alum heads, new valves, springs, harland sharpes, roller cam and lifters, intake, carb, and oh of course, the 2500 (or there abouts) 445 scat stroker kit with h-beam, rods and race bearings. And of course, the machine work.....I believe it is worth having them check it out thoroughly.

Then I'll polish everything inside for oil control and round all internal corners to relieve stress points and get rid of the casting slag. Then to assemble.

Pics will follow.

Thanks again guys!
 

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well from my understanding

a 352 can be bored to 390 but don't leave much meat left over..
plus another .030 .......I say no way... it would be tin foil cylinder walls...

360 and 390 same block just different stroke....

think of it this way... 352 & 390 may start out having same thickness cylinder walls..(cast same externally but internally different)....
.. but 390 cylinder is .050 bigger from get go...
and removing .030 is no problem....

but doing a 445 from a 352 will require to remove .080

the money it takes to build a stout FE....
IMO,I would keep looking for the correct block.... ;)
 

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Can I be honest dude?
If you are going to have $10k in the engine.... why start with a 352 block when a standard bore 390 block can still be had for $200?
 

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Discussion Starter #11
Yeah....I am constantly thinking of either buying another bare block or just using my original (MAYBE) the other one was supposed to be a 390, came out of a cougar and the guy was there when it came out. But after inspection, it was indeed a 352. The best part...no matter now....was that it was free.
 

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If the 352 & 390 were the same casting, then boring a 352 +.080 and a 390 +.030 would still be the same thing, wouldn't it?
 

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Discussion Starter #15
Any chance on shipping one freight? maybe by Amtrak? There is a station in Newport News not far from me.

Be glad you didn't use those heads as they were lol Had to put in all new valves. 6 of 8 were bent (visibly). Had 3 angle jobs done on the new ones. Shaved them .004" and cc'd to 73 now.

Anyway, really, any chance shipping one?
 

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crap.... so sorry to hear that. Wish I'd have known.
No on the shipping a block, they are not mine (i've got my own stash, but they aren't for sale). I just have a bud in north GA that has a number of standard bore 390's.

Stephen Christ, author of How to Rebuild your Big Block Ford
Interesting. Isn't this the same guy that makes every dude that has an F250 think he has a 428? :p
 

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Discussion Starter #17
Any chance he would be willing to ship? I would be happy to cover the cost.

Looking for a 65-67 or maybe a 68. I want the 3 bolt mount to fit.
 

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If the 352 & 390 were the same casting, then boring a 352 +.080 and a 390 +.030 would still be the same thing, wouldn't it?
Not exactly what I said .....
But...
yes they are the same with exception of cylinder walls...

Let me clarify my train of thought...
Let's say for example. Cylinder wall is 1/4" thick
352 with a standard 4.000" bore and 1/4" walls
360&390 with a standard 4.050" bore and 1/4" walls

really no big question which block to use and have bored out to 4.080"

Turning a 352 into a 390 ...
Not a big deal... But if cylinders get scored .. It have pretty much already been taken to the limit and is toast...
 

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I think the cylinders are all the same outside diameter when the block comes from casting. Say, 4.50". When Ford bored a 352, a 4.00" hole, you end up with walls .25" thick. When they bored a 390, a 4.05" hole you end up with walls .225" thick.

That being said, when I brought my 390 in to get bored .030, the machinist told me the #1 cylinder just "barely made it." He ended up boring it a hair bigger than the other ones and marked the largest of the pistons to remind me to put it in #1. I can't really visualize what happened but probably, either through manufacturing or 50 years of ageing, there can be some changes going on there that you don't expect.
 

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Not exactly what I said .....
But...
yes they are the same with exception of cylinder walls...

Let me clarify my train of thought...
Let's say for example. Cylinder wall is 1/4" thick
352 with a standard 4.000" bore and 1/4" walls
360&390 with a standard 4.050" bore and 1/4" walls

really no big question which block to use and have bored out to 4.080"

Turning a 352 into a 390 ...
Not a big deal... But if cylinders get scored .. It have pretty much already been taken to the limit and is toast...
What this is saying to me is that the castings are not the same and water jackets are bigger on the 352 over the 390 casting. My understanding had always been that the two engines used the same block, same casting. That would mean that a standard bore 352 would have a thicker cylinder wall than a standard bore 390, because the blocks are the same. I would think the 352 would have cylinder walls .050 thicker than the 390, if they were the same casting. Lots of meat in the casting provides plenty of tolerance for core shift, which seems common and supports the need for sonic testing before over boring. My understanding could well be incorrect.:tup:
 
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