Thread: pro topline casting numbers

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serious race head??... my plan was to take them to a shop to be hot tanked, and gone over and to see exactly what I have.. then put them on my 84 k20 pick up... has a 383 stock heads flat tops, with comp cams xtreme energy, lift .520/.523 duration 274/286, headers, holley 670 avenger...my question would be, could I put these on this motor, and see an improvement? and still use 89 octane? is there such thing as too much head?? haha

Sorry, duplicate post.

Originally Posted by bendougcarl

serious race head??... my plan was to take them to a shop to be hot tanked, and gone over and to see exactly what I have.. then put them on my 84 k20 pick up... has a 383 stock heads flat tops, with comp cams xtreme energy, lift .520/.523 duration 274/286, headers, holley 670 avenger...my question would be, could I put these on this motor, and see an improvement? and still use 89 octane? is there such thing as too much head?? haha

Yes, there is such a thing as too much head and you have found it. Those heads with flat-top pistons will make 12.0:1 in a 355 and 13.0:1 in a 383. The large 220cc intake runners will want more revs in a 383 to move enough air to create sufficient velocity to pack the cylinders properly, figure 7000/7500. Those revs will require a more expensive valvetrain, more rear gear and a looser converter, as well as more cam than what you presently have.

In the name of common sense, sell these turds and buy some heads with 75/76cc chambers and 200cc intake runners that will operate on the street with pump gas. 75/76cc chambers with the pistons you have now will make 9.6:1/9.7:1 static compression ratio, compatible with pump gas and your present cam.