Saw the thread referencing the 555 heads and speculation on whether it was an earlier version of the 333's got me wondering about the other small ports,it appears that the 817's & 333's are percieved to have superior ports to the earlier 379's,what about the 1147&586 heads do they have the same ports as the later heads?Also does anyone have experience with the 555's do they have chambers like the 333's and do they have the better ports also?
Small port heads
- Thread starter 427John
- Start date
As far as I can tell,the 1147,817 and the 333 have the same bowl size under the valve which is where they;re superior.The 379s and others are too thin to approach what the better heads are cast to in production form.The truck /industrial heads such as the 555 and the 702 were used on engines that the factory governed down to about 4,000 rpm.They were only concerned about torque in the idle to the point that they were governed to rpm range.Since they were using the double notched block to lower the compression,the head surface would be flat.
Don't forget those "in between" 1173s. We think those were the predecessors to the 1147s and 586s. I have a set dated 1960 I think, maybe 1959 I forget right now. Been thinking about letting those go 
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TomK
.TomK
I get that about the truck heads but that would apply to the 333's too.So I was just wondering if the earlier ones had the better ports also,if so and it were a double notch flat version except for valve size ,then it would be pretty much a functional equivalent of the 1147's & 817's wouldn't it?
Makes sense,bet that 409 truck motor felt like more than 20-30 horse jump over the 348 truck.