Can someone tell me what year chevy started making the cylinder walls thicker to accept the larger bore? I believe the earliest 283's were just bored out 265's so the cylinder walls were thinner. Is that true and if so, is it a problem for rebuilding? Thanks Rob
I don't have your answer, but your post had dropped off of the first page. Maybe the folks who have your answer wouldn't otherwise have seen this but this will get it back on page one (I've left this open hoping to see the answer too). I have been told that the later 283s also had thinner walls and that my '66 283 could not be bored enough to make a 301 out of it. Anyway, I'm interested in seeing the answer.
In the early 60s they were being bored and stroked to 352 cubes, if I remember correctly. I have read 1964 was one of the best years, but have always assumed any of them could be punched out .125. I cant imagine the 57's were just overbored 265's, but then I cant imagine that people live and die over their cell phones, either.
Time to hunt down the how to build 301 articles in old rod magazines. Before the 283 was called a small block as there were no big blocks yet. Had a couple of friends do it when I was young but didn't know that there was a difference in cylinder wall thickness then. Here this may be what you want. http://www.classracer.com/classforum/showthread.php?t=13114
many years ago a member did a post on this subject that had actual block numbers and the results of his sonic testing. i can not recall his name , and a quick search by me didn't find it. he was an engine builder and he built several engines that was given away as door prizes at the HAMB drags...maybe someone can remember him? anyway...i seam to recall that the early 60's ones was the best....but don't hold me to it
You should be asking about which casting numbers to look for rather than which years as that is more of an indicator which is more suitable. A 3737739 block is 58/59 production and had much thicker walls than previous blocks. A 59/61 3756519 block is similar. Yes, there were a lot of 4 inch bore 301's built out of 283's, but before I would do one today, I would sonic check the block. That being said, there is one Chevrolet 283 block you can safely bore to 4 inches. That is a 64/67 3790721 Chevy II block. Chevrolet used this casting for either 283 or 327. If you can find one originally bored to a 3.875 bore, just have it rebored. This was the hot item in the 70's for Modified Production small inch motors as the thick cylinder walls allowed for better ring seal at high RPM.
wonderful information, thank you! The one I am looking at (actually 2) but the one I'm most interested in is a 64, I will check the casting numbers on both. To my knowledge both are factory bore yet. I'm not looking to make a monster motor, if possible I'd just hone the cylinder walls. I'm looking to do a factory build if possible. Thank you so much! -Rob
The Nova 283 blocks were a real popular choice for machining to large bore diameters. The block casting number is 3862194 but they are getting hard to find, at least at a reasonable price, compared to the non Nova application blocks which are 1/2 the cost. Don't even try to find a "721" block unless you have deep pockets as the matching number L79 (327) Nova people pay big $$$ for them and they were only used for very early 66 model year production, the "362" block was the one used thru end of production. I believe the 65 Nova 300 hp 327 cars also used the "721" block.
I just looked at the casting number 3834810... Looks like it's a 64-66 2 bolt main. I mean it runs supposedly and it's $200 so. I will have to get the number off the other one later today then decide.
You may already know this but by your post above it kinda sounds like you thought they were available as a four bolt main block also. The Corvette 327's didn't even get four bolt mains. 283's never were available as a 4 bolt main.
Honestly I didn't know that but when I had looked it up I didn't think about it. I wasn't concerned really about 2 or 4 bolt mains. Just a stock rebuild/clean up anyway. I was concerned because if I find one that needs to be bored and had already been bored I wouldn't be able to. I think I should be good though. I went and looked at one it needed up being a 58 and also not complete. I'm going to look at a 65 tomorrow. It's complete I'll look at castings to confirm the year and info. Thanks a lot everyone! -Rob Sent from my iPhone using H.A.M.B.
The '56 265 991 castings can safely be bored .125 while the 57 265 548 castings can go even more.About .165 I believe.. 1958-62 283's also had thicker cylinder walls & can be bored to 4.000" when new. In 1963 until 1967 GM changed the 283 & the cylinder walls were thinner. I believe about.060 was about the most you could go with those.
In 1967 I bought a junk yard 63 283 and had it punched out to a 301 and had no problems with the cylinder walls. However it did run a little hotter than a 292 I built. For what its worth
never had the problem in my '64, but there were a rash of bad camshafts around that vintage. i remember guys punching them out .120 back then to make a 301, but never heard of a preferred block for it...
I read in an old magazine that 58 to 62 blocks had the thickest cylinder walls, and were the preferred block to bore to 4.00 inch. I just rebuilt a 327, cast in November of 1961, and even my machinest commented that it had thicker cylinder walls than he had seen before.
In the summer of 1960, my buddy and I took his 265 in to the local machine shop to ask if it would bore out to a 283, and the answer was yes. The engine was bored and there were no issues. Bob
O this happened today. It's a 1965 283 from a really nice looking Bel Air. Should work well with my project Sent from my iPhone using The H.A.M.B. mobile app
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