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  #1 (permalink)  
Old 03-24-2004, 01:31 PM
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Default 428 max bore

In my quest for a 428, I keep coming across parts with .030 overbore and .020 turned cranks that need yet another overbore and undersize on the crank. I will definitely consider sonic testing, etc. but at what point have these parts become impractical to rebuild?
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Old 03-24-2004, 02:04 PM
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.030 for a block seems to be ok. I see 428's go .060 with a sonic check no problem. It depends on the block and core shift involved. Cranks at .020 can still go more without any issues with .030 ideal. As long as these parts are clean without deep scores you should be ok but the machine shop will know the best. You can look into the Scat cranks if you can't find anything to suit your needs. G.
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Old 03-24-2004, 05:18 PM
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I agree with FFR428. . 040 over on a bore and .020 on a crank is fine for a street car up to about 450-475hp. This assumes it was a 428 to begin with, not a bored 390. Beyond that a sonic check is very advisable.

With these blocks disappearing every day, you can't get too picky. Otherwise a Shelby or Genesis block is your only alternative. Mucho more $$$


Good luck.

John
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Old 03-25-2004, 03:51 AM
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Default More and boring and crank turning

The maximum the block can be bored will be as stated above, it will mainly be dictated by the results of the sonic check. Personal experience has found the CJ blocks being less conducive to boring over 0.030" as opposed to the standard run of the mill passenger car blocks.

Turning the crank though can be as much as 0.050" as the bearings are available. There will be no wear issues with a crankshaft turned this far but care must be taken in that the oil holes for the journals move closer towards the journals edge when starting to turn crankshafts more than the generally accepted amounts. This can usually be spotted before actually turning the crank if being looked for. The other thing to watch out for is that shop doing the crankshaft grinding puts the correct radius at the journals edge in order to maintain crankshaft integrity in this area.
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Old 03-25-2004, 08:55 AM
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Thanks for the info.
The block is, in fact, a cj and they want $1100 for both.
I am still kicking myself for missing a local 428 that went for under $400!
jschiller, are these blocks "disappearing" or are they simply being hoarded?
(I'm not trying to be negative). It's just that I have had success obtaining much rarer (more limited production) engines outside of the Ford FE family even at "speculated" values. I'm also wondering if a lot of these motors are going to suddenly be available once the production of the Genesis block really starts. Just thinking out loud guys. Thanks .
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Old 03-25-2004, 09:23 AM
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So how far can a 427 block be bored?

Ernie
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Old 03-25-2004, 10:07 AM
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Ernie,

30-over for an SO is what I've been told, but there are always different opinions. Mine's currently at 22-over with a 428 crank = 454 stroker.
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Old 03-25-2004, 10:34 AM
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Mine is 15 over with 428 crank, I was told that is 454. so yeah, that sounds about right (15 to 22 over bore) for 454 cubes with 428 crank
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Old 03-25-2004, 01:33 PM
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My 428CJ is .040 overbore.
Bob
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Old 03-26-2004, 11:51 AM
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Default Disappearing blocks

The blocks are disappearing because they are getting used up and blown up.

There may be a few hoarders but not many I suspect. The hoarders who plan to sell the blocks in anticipation of the Genesis blocks coming on line will get the best price BEFORE the mass release (if it ever happens) of the Genesis blocks.

I dont see that happening at the moment. Either the hoarders don't number very many, or they don't see the Genesis as a threat to their future profits(i.e., they don't think there will be many Genesis blocks anytime soon).

I suspect those who plan to sell when the moment is right are still waiting for the right moment, the rest will sell only when there is a market for their original block for resto purposes, etc.

John
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Old 03-27-2004, 03:55 AM
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I think most of the guys holding blocks are rebuilders and part vendors. I know a few builders have a large selection and keep them only for rebuilds and are not for sale as bare blocks. I bought a NOS 428 service block 2 years ago for $1300. The same vendor still has a few and now sells them for $2250. These were a large number of NOS 428 blocks that were found in Canada years back. So prices are still on the rise but if you look you still can find a deal. I know DSC motorsport (vendor here) has some nice std bore 428 blocks as well as everthing else for the FE. Prices are also good and all blocks are checked. G.
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Old 03-27-2004, 04:00 AM
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Oops, maybe DSC not a vendor here... sorry www.dscmotorsport.com
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Old 03-27-2004, 04:13 AM
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There was an article I saw on this subject for the 427 and 428 FE blocks either in an old copy of Shelby American or SuperFord.

They did some block research using sonic testing to cull out those blocks that on the surface appeared to be "overboreABLE". The sonic testing revealed that all cylinder walls are not alike, some were perfect and thicker while perhaps one of the eight was very thin causing the block to be considered unboreable.

The hard part was to find a block that had sufficient wall thicknes and concentricity to allow uniform overboring for ALL eight cylinders.

They were able to use sonic testing equipment to find such blocks.

The take away factoids I remembered were:

1) that not all blocks can be overbored due to one or more thin wall(s)
2) FE blocks with equal wall thickness all around are somewhat rare
3) overboring reveals occlusions or voids at times
4) old blocks are stable and pretty much stress relieved due to thermal cycling
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Old 04-06-2004, 06:48 PM
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Can a 390 be punched to 428 ??? I was under the impression that 402 was it......
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Old 04-06-2004, 07:09 PM
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By punching to 428, I'm assuming you mean to a 4.130" bore? That's 0.080" over and would highly recommend sonic testing the 390 block in question to insure it will have adequate material remaining before hitting it with the boring bar.

On the other hand, if you're just looking for 428+ cubic inches from a 390 block, then consider a SCAT 4.125" or 4.250" stroke crank which would take a 0.030" over 390 block to 431 and 445 cubic inches respectively.
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Old 04-06-2004, 07:26 PM
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Sonic testing is a must, usally a CJ 428 can go 30 over , anything else is taking a risk. tout
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Old 04-15-2004, 01:45 PM
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Rickster, when in doubt, have your block sonic tested. If you do any performance driving, do NOT use a block that has anything less that .125 (1/8th inch) wall thickness.

If you still have doubts, talk to those who know the limits best, past national record holders, Aldon Miller Idaho, Richey Pauley California, Jim Waldo, Washington. .125 for street or strip is the rule of thumb.

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Old 04-15-2004, 03:00 PM
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Rickster,

I had mine sonic tested and it is bored .065 and I have never had a problem with it. But the sonic testing I feel is a must.

Ron
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Old 04-16-2004, 12:49 PM
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Ron61, what engine did you bore to .065? Was it a 428, or your 351W?

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Old 04-17-2004, 08:37 AM
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Default 427 Max Bore?

Can a 427 block (1964 CO) be bored 040 over? If so, are "off the shelf" pistons available for this bore?
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