350 engine .080 overbore

Hi all! I bought an engine last week at a race auction. It is a shortblock 350 chevy, with flattop .080 sealed power pistons. This is freshly put together, so the piston tops are new, I can see the .080
stamped on them. Normally, I have heard of overboring these engines .030 or .040 over with no problems, and .060 over if the block was cast well. I've never even heard of .080 being available for these! I don't think I will use it for racing, we run circletrack on a 1/4 mile track, but my truck needs a motor so I was thinking of throwing some heads on it and trying it. Anyone ever go this big on an overbore? They make the pistons, so I assume it must be feasible, I'm just a little wary. I got a good deal, $350 for this, so I figure it was worth a gamble, if nothing else I could pull the crank and stuff out. ( supposed to be .010 mains and rods ) It also has a new oil pan and timing cover and harmonic balancer, but I would rather just assemble the top end and run it. Any opinions/comments/experiences are appreciated! Thanks, Earl
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really bad.. good price but I'd hate to see what will happen if you put 300hp or higher through it and get it too hot just once.. Why would anyone do that..

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wrote:

I do not think I would even fire it up. 040 over is considered max and 060 is pushing the limit. 080 over is asking for trouble. ----------------- TheSnoMan.com
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Interesting. I have a 350 bored to 4.15 and it runs in the 10's. It's a Chevrolet Bow Tie block.
Al
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there that will take a bigger overbore and that have siamezed cylinders. A stock 350 block will not do that becaue there is not that much meat in there. ----------------- TheSnoMan.com
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Chevrolet wrote:

shift and it has the thicker walled block it MIGHT be OK.
--
Steve W.
Near Cooperstown, New York
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wrote:

Even still I would be worried about the likelyhood of sand cast holes with thin walls. ----------------- TheSnoMan.com
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thicker walls some can go out farther than others. As far as .080" I would check to see if the block has been cemented (epoxy filled) look down in and see if they filled the block. We have done that to 1/4 mile engines, makes them stronger and doesn't hurt because they only go 1/4 mile at a time, don't have time to get too hot. But stated in previous .060" is usually too far and can fail... I know I would pull out all the good parts and just throw them into a different block, but that's me and I have a half dozen or so 4 bolt blocks on the bottom shelf just waiting for parts. $350 isn't bad for a bunch of good parts...
Just my opinion or comment,... Good Luck Earl
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Thanks for the comments... I just hate to throw away a block that is so shiny! It is a 4 bolt main, with a lefthand dipstick so it is a 70's engine. ( I haven't ran the casting numbers to see exactly what year it is, but being 70's maybe a better chance of being a good casting? ) Worst comes to worst, I guess I have a good crank, bearings, timing chain set, new Howards solid cam .510 lift 288/288 duration ( spec card was included :) ) , new oil pan, balancer and t- chain cover, rods and oil pump to save. Next question.... if I feel brave and bolt on some heads and try it, what would likely happen IF it fails? I assume it would be a cylinder wall failure, which would take out the block, piston, (which wouldn't matter much at that point), and anything else? Most likely the crank and heads would survive, maybe? I'm still thinking that for the price of a gasket set and my labor, if the rest of the good parts would be salvagable after a failure I might just try it in a street vehicle. ( but not for the track because of the heat and stresses ) What about this idea? Again, I really appreciate all comments, thanks! Earl
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Like everyone has said.. not good to go over .40 BUT anyone with half a brain would not do it without making sure it would work.. I assume this guy seeing as all the parts he had in it, would have checked to make sure it was strong.. The guy who machined the block (unless a crooked asshole) would advise against this over size.. BUT then again.. he gets paid whether it works or not.. Don't turf it.. HELL if I had the setup, I'd use it anyway....just to rub everyone the wrong way and brag I had a .80 350 ..I'd drive it like a nun... nice and easy at start.. once I was bored with the "new feeling" I'd drive the shit out of her till she threw an ovary LOL

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On Mon, 22 Jan 2007 22:03:06 -0500, snipped-for-privacy@webtv.net (big e lewis) wrote:

GM also made a 400 SB with a 4.125 bore but it had siamezed cylinders (no watter between them) to allow for more wall strength. .080 over is a lot of material to remove from block (.040 on a side) and too much too for a 350 block. The eprson that built that motor likely had second thoughts about it and got rid of it. Strip the good parts off of it like someone suggested, scrap or sell the bare block and call it even. ----------------- TheSnoMan.com
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You could try it and hope you get lucky... We ran a 400 block that was punched out .060 over... way too much for that, it lasted about 10 runs but we got lucky and it only cracked a cylinder and started puffing out white smoke... luckily no damage other than the block was junk, we were able to salvage all other parts. You just have to hope that it don't let go and hydro the cylinder or bust and let the piston cock in the bore and destroy a lot more... P.S. that cam isn't going to be too good in a truck... hopefully a very light truck, a lot of stall, and low gears...

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