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283 CHEV BLOCKS?

General engine tech -- Drag Racing to Circle Track

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Jeff
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283 CHEV BLOCKS?

Post by Jeff »

Was checking sizes , to order parts for a 283 chev and its been bored to a 4" bore. I do not own a sonic tester, so can anyone tell me if these blocks are thick enough to safely overbore 0.125 th. The casting # for this one 3731548. I would have to take another .020 out to use, or look for another block.
Jeff.
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Post by Ed-vancedEngines »

Tons of those were build to be 4 inchers. Anything beyond that, I would be guessing. The 301/302 SB Chevy engines were one of the more popular combinations way back when. I can not see why a very small over hone would not be ok though.

Ed
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Post by bill jones »

-I bored a 1967 283 block out to 3.998" and used a set of standard bore but well used 350 pistons along with a 3.550" stroker crank.

-This block had a curvature about 2 to 2-1/2" wide where the counterweights swing so the 350 steel crank I was using fit with no problems other than the main bearing oil holes being so far offset from grinding the 350 mains to small journal.

-I have a set of tongs that I made to measure the bore wall thicknesses reaching down thru the water jackets---and I found the block to need to be offset bored to save what little precious wall thickness there was.

-This measuring and boring process took much more time than normal but I feel it ended up being a neat engine for a nice street driver.

-But it ended up in a dirt oval track car in Georgia----ran 1500 competive laps---mostly on dry slick tracks.

-It got freshened with new ring & bearings---changed from a wet sump to a dry sump.
-Maybe during this first rebuild or somewhere along the way it got a set of nascar honda journal sized rods and lighter pistons etc----stroked the crank a little further and bored out to 4.020" and ran another 1500 laps.

-All of this was with the stock two bolt mains but using ARP studs.
----------------------------------------------------------------------------
-During another rebuild it was found the rear main cap was cracked down both sides of the main studs---and over to the oil drain notch just in front of the rear main seal.

-Everything else looked to still be in excellent shape---so I ground the cracks wide open and brazed that main cap up---detailed the brazed area real nice and shotpeened the cap.
-The block has since been align honed and the main cap was not distorted from the brazing enough to cause any problems---so the engine is going racing again this summer.
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-I don't have any idea what the block is that you have----I don't know about the casting numbers---but those old blocks were pretty thin compared to the power we are expecting out of engines today.

-Where your block has already been bored there's nothing you can do to help save any precious wall thickness with offset boring--so you'll either have to just go ahead and do it---or maybe get the block sonic tested or build a set of measuring tongs to measure the wall thicknesses.

-I have seen more than one 327 with .070" thick walls at the front or rear of the cylinders like between the cylinders---that ran pretty good "back in the day".

-If you are going to run a 283 3" stroke I wouldn't worry about it much as those short strokes just don't load the cylinder walls like a 3.480 or 3.750" stroke does.
-The heavy pistons for those old 302's had long wide skirts that were real easy on cylinder walls.
----------------------------------------------------------------
-I might have the bre wall thicknesses written down somewhere---and if I can find it I will come back with that info---maybe tomorrow.
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Post by Ron C. »

They had a lot of core shift problems with 283 that were being bored out to 4". Just make sure you got a good one. As I remember from those days there were more that didn't take the 4" bore than ones that did..

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Post by PackardV8 »

IMHO, Better pay someone to sonic test it or find another block. Personally, I would never run a SBC 283" at 4.020". In fact, unless it were for some numbers-matching restoration geek, there is no good reason to ever build another 283". Parts cost more than for a 350".

Yes, Ed, I was there, too and saw thousands bored to 4" as the 301" was considered the hot setup in the late 50s/early 60s. It was often literally the hot setup, because it left some cylinder walls so thin, it caused many of them to run hot. Taking that much iron out also left the block as limp as a noodle. You want to see cylinder wall flex, bore a 283" to 4.020" and then bolt on a torque plate to do the honing - the cylinders will look like a coke bottle. Many real racers mostly stayed with .0625" and their 292" were usually faster and lasted longer than the 301"

thnx, jv.
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Post by C Stevens »

Look at the underside of the bores, if the area is flat instead of curved, don't even think about a stroker...even 3.25. Don't ask how I know. :cry:
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Post by Ed-vancedEngines »

Well Jack,
Back then most of us had never heard of or had even thought about torque plate honing. Cylinder wall thickness? What that meant was you did n't hit water when you got your block bored :). Block filling? No way am I gonna add any more weight. :)

Jahns Pistons and Clay Smith cams were the order of the day but there were probably more of the 097-098 Duntovs around.

IN the D/Stock class at your local track was where many of those 301's showed up. 301 with a 2 x 4 Corvette intake.
They were the hit of the streets until Mopar-Ford showed up with thier Factory Showrooom available Hot Rods.

Ed
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Post by bill jones »

-Ok---here's what this stock 1967 wall thickness ended up with after offset boring the block to 3.990"---and just prior to the final hone using a sonic tester (instead of the tongs I had mentioned).


-1-.172"non thrust walls-----.135"thrust walls
-3-.176"--------------------------.152"
-5-.175"--------------------------.164"
-7-.168"--------------------------.191"

-2-.163"--------------------------.204"
-4-.155"--------------------------.189"
-6-.160"--------------------------.182"
-8-.167"--------------------------.193"
---------------------------------------------------------
-1-.216" front----.106"rear
-3-.123"-----------.125"
-5-.114"-----------.107"
-7-.117"-----------.191"

-2-.171"-----------.112"
-4-.119"-----------.128"
-6-.113"-----------.103"
-8-.146"-----------.170"
---------------------------------------------------------
-Reviewing these numbers I feel they are actually pretty decent----but I really don't like the .135" thrust wall---even tho we have already moved the centerline on that hole as far as we could which was something just less than .060".

-If you look at the front and rear of cylinder # 5 and #6 they are within .007" to .010" of being perfectly centered front to rear--so even tho they are the thinnest pair of walls there just isn't much more you can do with'm.

-Having a method of measuring the wall thicknesses was a BIG deal with this old block.
Ed-vancedEngines

Post by Ed-vancedEngines »

Whew!
Man' Looks like we were all flirtin with danger way back when. Thankfully we didn't have any nitrous back then. That might also explain why a 292 seemed to run a little better than basically the same thing in a 301. one time.

Very thin stuff.

Ed
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Post by CNC BLOCKS »

We had a guy show up with a newlt revuilt 302 short block uing a 283 casting that another shop just built and they did not sonic test the block and when we sonic tested it we found that one of the thrust sides was only .088 thick and I believe it ened uo on ebay.
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Post by PackardV8 »

Interesting that Carl found a block with .088" walls and bill jones moved another cylinder bore centerline .060" to maintain a .135". Put it back that .060", because it wasn't done that way in the bad old days, and that cylinder thrust wall would have been .075". Anyone want to bore it another .020" and send it out with your name on it?
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Post by Jeff »

I appreciate all the feed back, the block is out of a customers 57 chev that will be abused. So I will dig up another block, put that one in the corner till I buy a sonic tester. It was built into a 327 combo. He kinda wanted the #'s to match the car.
He is having me do 2 engines for each car, a 55 chev and 57. The 265 and 283 are suppost to be stock rebuilds. Then the 2 327's are going to be built to be abused. No matter what I build for him they will be pushed to the limits. :lol:
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Post by CNC BLOCKS »

Jeff wrote:I appreciate all the feed back, the block is out of a customers 57 chev that will be abused. So I will dig up another block, put that one in the corner till I buy a sonic tester. It was built into a 327 combo. He kinda wanted the #'s to match the car.
He is having me do 2 engines for each car, a 55 chev and 57. The 265 and 283 are suppost to be stock rebuilds. Then the 2 327's are going to be built to be abused. No matter what I build for him they will be pushed to the limits. :lol:
Thanks Jeff
Is that the block with no motor mounts on the sides as I have one of those in the shop for sale and its a 283
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Post by mtkawboy »

Back in the prehistoric notech 60's, I had a 301 in my Vette for five years that survived 2 years in a late model modified winning 38 straight features in the process prior to going in the Vette with nothing but a cam change. The pistons sounded like they were swapping holes at idle but we didnt know about wall thickness back then, it either did or it didnt. The thing was a rocket in ts day. Maybe I was just lucky. No one ever tried more then .125 over that I know of. 301's were very common but some ran and some didnt which is where the wall thickness comes in Id guess. After breaking a crank in half at 7000 I put a 327/360 motor in it
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Post by JBrady »

Any opinions on sleeving blocks? Could save the "numbers matching" block and give back wall thickness and strength. Just a thought. Darton does some interesting sleeves for LSx applications. Not sure about older blocks.
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