Im guessing the casting number ends in "520". standard equipment witches hat used on all 283 motors. some people refer to them as power pack heads, but not high performance, just better than the ones used from 1962 and older on 283. those earlier ones did not have the witches hat, and usually had smaller valves prior to 62.
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Beaumontguru
MY BEAUMONT HAS 4 STUDDED TIRES AND 2 BLOCKHEATERS......AND LOTS OF OIL UNDERNEATH. The other one has a longer roof.
standard equipment witches hat used on all 283 motors.
Yep.
I have camel hump heads on one of my 283s. After some research, I've found that camel humps weren't really all that awe-inspiring performance-wise, contrary to belief.
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Prince Edward Island
'64 Parisienne CS "barn find" - last on the road in '86 ... Owner Protection Plan booklet, original paint, original near-mint aqua interior, original aqua GM floor mats, original 283, factory posi, and original rust.
The power packs I have here are 896 cast but I think they are Canadian so might be the same/similar thing as a 520 just different foundry. From what I've heard they are good for a 283 with a standard bore or small overbore. You can stick 305 1.84" intake valves in them and work OK, or use fuelies with 1.94 intakes but really need a 60 or 125 thou overbore.
I tried using 305 heads on a 283 once. With standard 4" bore gaskets the water was awful close to the gasket edge, ended up with a set of Felpros that just worked but the water ports on the heads were awful close to the metal rings around the bores. With proper 283 head gaskets they probably would have been OK.
I have what was a running 283 here with 462 fuelies on it. Have to take the heads off to clean up the valves as its been sitting for a while now and looking at them with a flexi camera up the plug holes they need a valve job. If it has a 4" bore I'll leave them on but if its STD to 40 over I'll be changing them out for the 896 power packs as I don't have any 305 heads. The other heads that might work if it has a 60 or 125 thou overbore are a pair of early Corvette alloys, they are 58cc or so with 1.94 intakes.
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I have a 62 with 283 and 480 heads, pure junk! The 520 power pack heads aka witch hats, are a much better head and also used on the lower hp 327's which came out in 62. 1958 - 61 you could get the 283 with a 4bbl and it had 230 hp. This engine was know as the Super Strato-Flash and had 9.5:1 compression with power pack heads and different cam. The 58 & 59 2 bbl 283 had 185 hp and dropped to 170 hp in 60 - 62 with 8.5:1. Starting in 63 to the end in 68 the 283 was only available with a 2 BBL and 195 hp. 1958 & 59 the 283 had a 2-4BBL option producing 245 hp and in 59 a fuel injection option with 290 hp. Unfortunately, I didn't dig into the various head options but my GM 61 & 62 manuals clearly show different specs for the heads on the Strato-Flash vs Super Strato-Flash. I don't know how much help you find this info but it may help you in searching different years for different heads knowing what power they produced. The information I provided here was for factory engines. I did read an article that said the most hp ever out of a 283 was 315 and it memory serves me correct that engine had 2 - 4 BBL and who knows what else done to it.
The 315hp 283 was a Corvette engine if I remember correctly and was fuel injected. It had the original fuelie 461X heads. Was essentially a 283 with good heads and solid cam plus 2.5" exhaust manifolds. It was replaced later by the L84 375hp 327 which was basically the same thing but with a larger bore and longer stroke (L84 was an L76 (365hp) with injection).
