[racegto65]

If somebody wants to ship a 350 to me in Las Vegas,Nevada, I can sonic check it and then throw it on my boring bar and cut it until I hit water. Then everyone will know.

[taff2]

Why bore it to 4.120" ? Bore it to SBC size of 4.00" for 383ish cu in and open up a world of cheap ,lightweight pistons!

[Firebob]

Seems to me that's what the knock on the stock 400 chebby engines were. They had heat problems because a 350 block was cut to 400 bore and the walls weren't thick enough. They had a tendancy to heat up. That was the buzz back in the day anyway.

Robert

[screamingchief]

That SBC info is'nt exactly true,the 400 SBC is a siamese bore block,ie. the cylinder bores are all connected together internally to gain the needed cylinder wall thickness,thus they lack cooling between the cylinders,hence the heating issues.

Now a 4" bore would be a much more realistic "maximum goal" bore to consider for a deal like this IMO,and with a 4" stroke you would have a "square" combination B/S wise.

That combo would yeild 402 cu.in.

The pin heights will still likely be different though,so dont count on being able to use "off the shelf" pieces for other brand engines.

And it would still need to be verified by a sonic test of all the bores on the block in question,and it may take checking a couple blocks to find the "right one".

As well I'd want to fill the block to the freeze plugs for some added support for the bores (just to be safe),and I'd also plan on using an oil cooler for any extended "street" miles.

[hal101]

what i heard was the sbc 400 had siamese cylinder's
and that was the cause of the cooling/overheating prob's

[blkcrow]

A little off subject but I believe that whole chevy 400 thing was a myth-or they just didnt have an adequate cooling system.Ive built a few 400 chev engines back several years ago with zero issues-not even a hint of overheating with highflowing three cores or stock four core radiators.The big thing was to build 383 strokers but I always preferred the 400 for its ability to make the same h.p. at lower rpm and provide superior torque-great for a street/strip car.

[Scarebird]

the front of that #5 cylinder, is that really 0.028" thick???

["Puddles the Pontiac"]

Originally Posted by Scarebird

the front of that #5 cylinder, is that really 0.028" thick???

no, that was an ink splotch. the reason i showed that was because this was the engine i used everyday. driving and racing. for three years, it was used in my daily driver.most would think this is too thin. i want to offset bore it even more. thought it might relate to the topic.
p.s. anyone ever go more that 4.211?

[77formula]

I have a couple of 350's at the shop. let me know if I'm close enough. I'm in Johnson City.

[74Grandville]

I would like to know if a 350 can be bored to 4.00" this is about a .120 overbore 4" bore/ 4" stroke sounds like a cool 350. looking at a 400 compared to 350 I don't think there is anyway to bore it to 4.12

[77TA406]

I have a 1975 standard bore 350P in the hot tank right now and will do more measurements after it is cleaned up, but for now, I don't think it will be possible to bore a 350 out to a 400. Here's why...correct me if my math is wrong. Through a frost plug hole, I measured the distance between the cylinder walls and got .381...I also measured at the top of the deck and got a measurement of .748 between two cylinders. This leaves a distance of .367, but since that figure includes the thickness of two walls, it must be divided in half, which only gives us a wall thickness of .1835. As stated in the post by bobzdar,a 350 will need to be bored out .245 total, or .1225 per wall. This would only leave .061. Maybe my math is wrong...let me know opinions.
Chris

[bobzdar]

If the minimum 'safe' wall thickness is .200...How could a standard bore block only have .1835 thick walls? I'd have to check it out to see, but perhaps that is correct, or perhaps there's a lot of core shift in that particular block?

[77TA406]

Hi all. I have now measured four different blocks...three 350's ( 1974 & 75 ) and one 400 ( 1977 ). and here is what I have found. The measurements are not accurate to the thousandth, but will still give everyone the answer they are looking for. When measuring the distance between the cylindrer walls through the frost plug holes, all the 350's were approx. .370 inches. When measuring the distance between two cylinders on the deck (where the head bolts up), all the 350's were approx .745 inches. If my math is correct, that gives a cylinder wall thickness of approx .187.
On the 400 block, the measurement through the frost plug hole was approx .210 inches and the top measurement was approx .495 inches, which, if my math is correct, gives a cylinder wall thickness of approx .142. I know that seems pretty thin, but thats how I calculate it. Either way, it's now obvious that 350 and 400 blocks do not use the same casting, based on the distance between the cylinders when measured through a frost plug hole. Earlier blocks might be different...who knows. If anyone else wants to recalculate my figures, I would sure like to know what they find...
Chris

[Jack Gifford]

Thank you Chris, for the research.
To he who said they seem awfully thin- remember that Chris is measuring fore/aft numbers- the wall thicknesses in the "thrust" plane may well be more.

[77TA406]

PJ...you are correct about the thickness in other areas of the cylinder. My measurements taken through the frost plug hole were at the widest...or thinnest point of the wall. The cylinder wall tapers at the top and bottom, so those areas are considerably thicker.
Chris

[greyno3]

I just bought a 1970 350 for $3.50. I did some research and .060 or 3.935 final bore size is max. Checkout this article link.

http://popularhotrodding.com/enginem...9PHREMPontiac/
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[greyno3]

Here's an article out of my 2003 Hot Rod magazine.

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[greyno3]

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