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1957 283 heads

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#21 ·
I'm confused, 997 heads with the towers were found on Vettes with the 220HP, 245HP, 250HP and 270HP engines.
Passenger cars with a 220 HP engines and 283HP engines had 539 heads with the pyramid? That is what I'm reading... Al
 
#22 ·
alhewitt said:
I'm confused, 997 heads with the towers were found on Vettes with the 220HP, 245HP, 250HP and 270HP engines.
Passenger cars with a 220 HP engines and 283HP engines had 539 heads with the pyramid? That is what I'm reading... Al
Click to expand...
That is correct.
 
#24 ·
That chart has many errors in casting numbers and applications. It has double tower 56 762 heads listed as 997 casting and single tower also as 997. It only shows 896 and 520 for pyramid PP heads and left out 58 770 castings along with many others.
 
#25 ·
alhewitt said:
I'm right in the middle of this subject with my engine shop. I'm having my 283" engine gone through with new components and the pistons are special to get to 10.5:1 compression ratio with the 539 heads. Or so I'm told. The piston guy wants the heads to measure and insure that the pistons do not have conflicts with valves. Back in 1962 I installed power pack heads (I assume they the were 539 series) on a new 340HP 327 short block. Cheep horse power as the new GM short block cost me $250! I'd give 10 times that today for one. There was no valve conflict with the pistons. So today my machine shop uses a piston manufacture that is unsure what domed pistons are needed without seeing the heads. Oh well better to be sure than sorry... Al
Click to expand...
If you use a flat top piston, and a 63 or 4 cc combustion chamber, and at zero deck height plus 0.48 thick Fel-Pro head gasket. You should have nine and half to one without a domed piston can achieve the same thing with a 30 deck with a 022 head gasket factory, GM steel shim Piston that is completely flat, which just to valve relieves
 
#27 ·
Your heads with the single hump in the middle are Canadian powerpack heads. The chamber is not like a US powerpack, looks like a US 2 barrel head chamber. I wonder what a Canadian 2 barrel head chamber looks like, maybe like a 55 -56 truck head chamber, larger than a regular 2 barrel head.
 
#30 ·
Leroy Falk said:
The 997 heads were quite special. Besides higher compression they came with swirl polished valves and came stock with double springs. I had a set on a 301 gasser and they ran great
Click to expand...
Yes, 997 heads are special, but they were not better. Unless you relieve the area around the back side of the chamber, then you basically a powerpack head because you loose the smaller chamber that the 997 has. The lightened valves were only on the 270HP heads, not the 250 or 245HP 997 heads. Double springs or dampeners?
 
#32 ·
Leroy Falk said:
Just telling you what I had. I had them all apart and did a valve job on them. If you don’t believe me, fine, but I know what I had!
Click to expand...
You stated that 997 heads( not MY 997 heads) but not all 997 heads came off 270 HP engines. I don't want people to get a wrong idea that all 997 heads had the same valves. If you had real double springs someone added them.
 
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