I did a search here, and was able to find where the numbers were on the block, but just not sure what it is. This is the number stamped between cyls 5 & 7 R495261. The casting number on the back of the block is 565528, is this a 1956 engine?......Thanks..Ed
That would indicate that the block is a '53. But as for the heads, well, is there a large number cast on the top of the exhaust port area?
The heads are also '53. Those 303 heads are OK for low-performance resto's on original Olds's, or OK for a hot-rod engine that you want to be period-correct to the early to mid '50's, but there are better heads you could use. Please note, the better later heads not only have larger ports but also larger valves. If you use the later heads for more performance, then it will be up to you to make sure that the small bore size of the 303 won't interfere with the either valves or the flow around the valves.
Those are the last of the 303 heads. They still have the original style small ports, but do offer more compression than the original style combustion chambers of the earlier engines (8.25:1 instead of 7.25:1). All heads had 1.75/1.44 valves through '55; the sought after '56 "10" heads kept the 1.75 intake, but went to a 1.56 exhaust valve. It wasn't until '59 that Olds opened the intake up to 1.875, where it stayed through '64. I'm going to run a pair of "3" heads on the 303 in my A, mostly so I can use the Fenton headers I've got. They won't work on the '54 and newer exhaust ports.
Guy's.... if it wasn't for the HAMB i would have spent days trying to research this on my own, thanks eveyone for the help...Ed
I just learned something from Heathen about when the valves changed. But I know the ports on the 303 heads are dismal.
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