350 small block boring

jacob54904 · #1 10-03-2006, 08:51 AM

Hey,
I have decided to bore out my 350 in my 92 chev suburban. I want to go to a 400, but i am not sure if i can go any higher or not. How big can i bore my 350 out to without causing any problems?

silicon212 · #2 10-03-2006, 10:26 AM

Quote:

Originally Posted by jacob54904

Hey,
I have decided to bore out my 350 in my 92 chev suburban. I want to go to a 400, but i am not sure if i can go any higher or not. How big can i bore my 350 out to without causing any problems?

4.040" and even that's cutting it close. Full safety is nothing beyond .030". The 400 bore is 4.125", these blocks are cast so that the bores are "siamesed"; cast together in between. The 350 is not, and your bores will be paper thin if you try to bore it this far, and with core shift it's not inconceivable that you will have portions of the bore that are exposing the water jacket.

bobss396 · #3 10-04-2006, 11:45 AM

I like .030 max myself. Not that this will get you a whole lot of extra power either without making other changes to the engine.

On many older (much older) engines they could stand a .125 overbore, as they were thick cast with a ton of meat on the cylinder walls. If a bore was cracked, it could be way overbored and sleeved.

Bob

jacob54904 · #4 10-04-2006, 12:45 PM

How much could i overbore a 350 out of a 83 pickup?

jacob54904 · #5 10-04-2006, 12:46 PM

Quote:

Originally Posted by bobss396

I like .030 max myself. Not that this will get you a whole lot of extra power either without making other changes to the engine.

On many older (much older) engines they could stand a .125 overbore, as they were thick cast with a ton of meat on the cylinder walls. If a bore was cracked, it could be way overbored and sleeved.

Bob

how much could i overbore a 350 out of a 83 pickup?

capriceowns · #6 10-04-2006, 01:08 PM

Quote:

Originally Posted by jacob54904

how much could i overbore a 350 out of a 83 pickup?

.030 dont go much over that, unless the machine shop says it ok, but even then its debateable.

If you want more cubic inched out of yor 350, make it a stroker. a 350 just cant become a 400

Rebel Racing 3 · #7 10-05-2006, 11:53 AM

We have taken 350 blocks out to 60 and i even know a guy that we built a engine for that took it to 80 i belive and he filed the block up with block concrete

corning_d3 · #8 10-05-2006, 01:24 PM

I would object to concrete, but there are partial and full block fillers. The only way I'd go over .030 on a 350 is if it was a big-block...

Rebel Racing 3 · #9 10-05-2006, 01:53 PM

Ok first, i ment block concrete, which is not the same concrete you would pour a driveway with, 2nd you can go to 80 over but also 40 60 over is not a prob with a 350.

Rebel Racing 3 · #10 10-05-2006, 07:11 PM

And block concrete=block filer i belive that we mean the same thing

silicon212 · #11 10-05-2006, 10:13 PM

Quote:

Originally Posted by Rebel Racing 3

And block concrete=block filer i belive that we mean the same thing

Block concrete is an epoxy, isn't it?

ANyways, I know that a 350 can be taken to .060 or so. .080 is a serious roll of the dice IMO. Anything over .040 tends to run hot on a daily driver street car. A race car is totally different.

corning_d3 · #12 10-06-2006, 12:15 AM

HAHA, I was almost 100% sure that's what you meant, but there are some people........ I'm weary of over-boring, though. I can change the cylinder bore dimensions on a block with the head removed by squeezing both sides of the cylinder with muh hands. It may only be a few thousanth's of an inch, but it still can be easily distorted.

Rebel Racing 3 · #13 10-06-2006, 11:50 AM

As for the engine's bored over 40 running hot i guess it depends on what you consider hot? I have taken 360's out of our race cars and run them in street cars and never seen the temp go over 230-240 (360=350 bored 60) and as long as you have some money in the engine ie good parts and stuff it should not have a prob running those temps

bobss396 · #14 10-09-2006, 11:28 AM

The main intention of a conservative bore job is to clean up worn cylinders. I would only take the advice of an experienced engine builder as to what is safe for a particluar block. In my opinion, if you want a bigger motor, go with a big block or a stroker.

For a stroker, avoid buying one from one of those mail order houses. You're better off dealing with someone locally that you can sit down with and discuss your options.

Bob

corning_d3 · #15 10-09-2006, 01:22 PM

True
and
True!

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