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FE Power Forums => FE Technical Forum => Topic started by: mike7570 on July 11, 2017, 07:45:38 PM

Title: 390 block again
Post by: mike7570 on July 11, 2017, 07:45:38 PM
I got my C4AE block back from sonic check. Back a few threads it was apparent the water passages were typical 390 not 428. The block has the webbing and has been cross bolted.
It was cleaned and magged (no cracks) but it is already at 4.13 bore, that should mean it is already at .080 over? A 13/64 drill bit was the largest that would fit between the cylinders.
The sonic map reveals thin spots on the cylinders and core shift?  I don't think I'm going to use it for my engine build.
The question is what do I do with this block now?
 
Title: Re: 390 block again
Post by: jayb on July 11, 2017, 08:53:28 PM
I agree, don't use that block for a performance build, it is way too thin on the thrust surfaces.  Not sure what to do with that one...
Title: Re: 390 block again
Post by: turbohunter on July 11, 2017, 09:45:52 PM
I am by no means an expert and I'm not trying to be know it all (I'm not), but that seems pretty good to me for a original block as long as it's straightened up deck wise and there are no other issues.
From what I've gathered over the years is if you've got .120 you're good to go if you don't want to get crazy. But wouldn't that block take 500 hp standing on its head and whistling Dixie?
I'd hate to see a buildable block go to waste and I don't remember how much power you want to get.
Title: Re: 390 block again
Post by: jayb on July 11, 2017, 09:59:32 PM
I was looking at the sub 0.100" numbers on the major thrust side of cylinders 1, 3, and 4.  Usually you want to keep the thrust sides at 0.125" thick minimum.  Those numbers are at the bottom of the bores, which is better than at the top, but still pretty risky IMO.
Title: Re: 390 block again
Post by: Tommy-T on July 11, 2017, 10:06:13 PM
Mike,

Your 'ol pal Tommy-T is just down the road with hard block in hand.

Interested in the block if you're "unloading" it.

gearhead427@verizon.net
Title: Re: 390 block again
Post by: mike7570 on July 12, 2017, 12:44:51 AM
I really wanted a BBM iron block for a stock eliminator build but they keep saying maybe.
I'm looking at 500+ hp (at least) to do that in a stocker usually means pretty high rpm's. I spent quite a few years piecing together some really good drive train parts and suspension pieces so I'm not going to rush the motor together.
Time to find a new block that will fit my needs. (Maybe if I sleeve down a 427 mmm)
Tommy-T, I work in OC and now live in I.E. Make an offer?
Mikeg@floorsbysignature.com
Title: Re: 390 block again
Post by: Barry_R on July 12, 2017, 05:25:57 AM
I'd go with running that in a mild street deal if the sonic is trustworthy - probably not as a racer.  I have run thinner stuff with a couple inches of hard block as suggested and it worked pretty darn well.
Title: Re: 390 block again
Post by: blykins on July 12, 2017, 05:29:43 AM
Typical 351c numbers at standard bore...

Last two Cleveland blocks I sonic tested had cylinders with less than .060" wall thickness between cylinders and around .125" on thrust sides.

I'd throw a little block filler in that one and turn the wick up on it.
Title: Re: 390 block again
Post by: George vega on July 12, 2017, 06:42:22 AM
Mike,

Your 'ol pal Tommy-T is just down the road with hard block in hand.

Interested in the block if you're "unloading" it.

gearhead427@verizon.net

You will have to re hone the cylinders after hard blocking as they will distort as the hard block dries. Leave it alone and use for street engine or work bench like mine.