Machining for 4 bolt mains

[Barry_R]

Sonic first. 
Please.
I have seen 390s with a standard bore that would have been marginal at .040 over.
I have seen exactly ONE that was good for over .100 wall left at 4.130
...of course we've only checked a hundred or two - the ebay guys must just have kept all the good ones...

Any sort well equipped modern machine shop should really invest in the sonic tester - a good one is a bit over a grand, but even a cheap oriental unit will give you a number to work with.

The cross bolt installation is pretty normal Bridgeport work, but the block is heavy, awkward to mount and work with, and it takes a fair amount of time to do.  You'll spend some pretty good money just on "clock labor".

[lalessi]

One of my questions would have been about minimum wall thickness at some point. I will report as this thing develops just as another "point on the curve". It may take a while though... I move slow. I have a retired machinist friend who owns a Bridgeport. Great feedback from everyone and I will continue to solicit advice along the way. I am looking at another machine shop, but the choices are limited locally.

[Bad Byrd]

Just a report back the sonic report shows min thickness of .136 as the thinnest which allows me another .030, From what I have read the magic number is .100.

[BH107]

For a mild street build .100" seems to be what most recommend. But with a stroker and the increased HP that comes with it I would want at least .125" on the thrust sides.

[Joe-jdc]

Why not only increase the bore by .010" and keep the wall thickness at .131"  It is half the overbore when figuring the amount of material left.  Pistons are readily available in small increments of overbore, even though you may have to pay a little more for them.  The added strength of the cylinder is worth the additional cost IMO.  Joe-JDC.

[machoneman]

As mentioned earlier on, why the cross-bolts on essentially a low-po block and one that will see mainly easy street miles? I'd do the sonic check, add the stroker but save the big $ for a large bore, cross-bolted 427 block down the road. JMO

[Bad Byrd]

As mentioned earlier on, why the cross-bolts on essentially a low-po block and one that will see mainly easy street miles? I'd do the sonic check, add the stroker but save the big $ for a large bore, cross-bolted 427 block down the road. JMO

Sounds like a bragging rights type of thing...............Which is I can get on board with, and a aftermarket 427 Block doesnt seem to be his plan on this particular car.

[Drew Pojedinec]

Lalessi, if your block doesn't pan out, I've got a C4AE block that is standard bore in good shape.
If I build an FE for my Galaxie, it'll be with an aftermarket block.

Anyway, I'm in south Ga if ya wanna drop in and take a look at it.

[bn69stang]

You need to sonic test for sure , and  .100 to .125 wall thickness is where you need to be and cross bolting if you re building above 550 hp imo , or maybe a main girdle .. you can buy a garage block from Barry for $ 3500 , it will cost you bout $ 800 - $ 1000 to cross bolt , so maybe look at the long run picture of a 427 block with the stroker kit and get 480 plus inches , or a 428 block at 463 inches .. Bud

[bn69stang]

oops  $ 3600 for garage block from Barry  my bad .. Bud

[cjshaker]

oops  $ 3600 for garage block from Barry  my bad .. Bud

If you are referring to the Sideoiler Garage block, they are already cross bolted just as the original 427 blocks that they are based on.

[Ididntdoit]

I think he was comparing the buy in on the side oiler garage block to the fact that he'd have an extra grand in the stock block that he wouldn't have to pay b/c the side oiler garage block was already cross bolted - what too many people seem to forget is that the aftermarket block (like a factory one) will still need another $1000 of machine work to make it worth using - real price $4600 and if you have to pay for shipping, almost 5k - for my build, I located a "local" block, and had it fully blueprinted - my total cost was half of what an aftermarket block would have cost me - for what I was going to do, it made the most sense - every build is different

[bn69stang]

Yeah i was referring to the expense of cross bolting an original block for probably 1 use , at max bore or spending the money towards a new block with lots of life .. Bud

[lalessi]

Hey guys, turns out the block was too pitted in one cylinder and would have to be sleeved. Cylinder wall thickness was .137 or there abouts on the block based on some free spot checking. All of your input actually helped me out in a large way. In looking for a sonic test, I found a new machine shop closeby that builds racing engines and they have FE experience! I would have wound up having more money in the block than it was worth to me. Off to devise a good plan "B". I have a good solid running 390 engine in my car now and may start with that. As a cubic inch guy I may start a 428 block search!!!
Thanks for all the help.
Lynn

[fe66comet]

If a block is nothing special, been bored already and heavy rusting has occurred it will cost more than it is worth to have it remachined to clean it up. Shops will not machine rusty parts so it will need to be blasted first. Get a stock bore block and start with one that is good from the get go. It will save you in the end, use the other block for a coffee table on your deck.