Thread: 383 build questions

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The only thing you need to change out are your heads. I have an Eagle rotating assembly with SRP forged pistons (-5cc) and I-beam rods in my 383. If you go to aluminum heads with 68-72 cc chambers (mine are 68cc AFR 190's) and a cam like a CompCams 280 Magnum which has an intake closing point at 66 degrees or a cam with a higher intake closing point, you should have no problem with using 91 octane like I do. A lower intake closing point will raise your DCR. For example, I considered CompCams XE-274 which has an intake closing point of 63 degrees, but that cam would have made my DCR 8.64 which is problematic (Anything over 8.5 with aluminum heads risks detonation.) My DCR figures out to be 8.469, and I have yet to experience any detonation. But I would not recommend my combination for iron heads. You can normally run .5 more DCR with aluminum heads. I would not worry about your Eagle rotating assembly. The only difference I have heard between SCAT and Eagle is that SCAT has a little nicer finish. But I have also heard that some builders prefer Eagle connecting rods to SCAT for some reason. Personally, I think it is a matter of comparing six to one-half dozen. My short block builder sells Eagle, and they are a highly respected machine shop in this part of the Midwest.