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BT casting failures

May 18 2017 at 7:35 AM
SSdynosaur  (Login SSdynosaur)

Response to Re: any idea on the cause?

In my experiences, Jay's assessment is absolutely correct. A solution already exists in the T&D inventory but it includes milling off the "as cast" T&D rocker mounts from BT and following T&D's method of mounting their "competition" FE rocker system on a Ford or other OEM-style, pedestal-mount rocker designed head. The revised method includes a 0.600 thick, secondary solid steel bar that bridges the intake port roof castings and ties all the upper head bolts together while also providing the mounting points for the previously included T&D adapter bar/plate for mounting the rockers. Obviously, this method removes all the valve spring opening load from the cylinder head casting and transfers it to the head bolts. While the HR head presents a worst case scenario for this problem I believe it exists, to some degree, in all the BT heads employing their supplied T&D mounting bosses. This is not a new phenomenon for the HR head design and was seen in many lower-end engine failures beginning in 63/64 for those who have been racing them that long. In defense of BT quality, when these designs were conceived, likely, NO one imagined they would be running with 400# seat and 1100# open pressures. If your application is less aggressive that simply means you can run more cycles before failure but no guarantee that it won't fail.

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