[HWYSTR455]

Originally Posted by 64speed

No they provided the pushrod length necessary. I was overloaded with information I didn’t understand yesterday but basically this is my 2nd go round with this. My Pontiac rockers just never made the grade with these heads but the BBC make the grade perfectly

So you gave Butler the length your builder provided and they shipped you the pushrods requested.

You should ask them about using BBC rockers, see what they say.

Bookmark this thread for future reference.

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[NeighborsComplaint]

Originally Posted by HWYSTR455

So you gave Butler the length your builder provided and they shipped you the pushrods requested.

You should ask them about using BBC rockers, see what they say.

Bookmark this thread for future reference.

.

Already called it after the first motor broke. It's the rockers.

Interesting tidbit ... assume for the moment the OP was running the Lunati 712 cam in the ill-fated motor. With 1.7 ratio rockers his lifts were .606"/.623" (I/E). If the rockers were 1.8 ratio, .642"/.660" (I/E). If the cam was the 713 , then .634"/.640" (I/E) w. 1.7 rockers and .671".678" (I/E) w. 1.8 rockers.

[1968GTO421]

Originally Posted by NeighborsComplaint

Already called it after the first motor broke. It's the rockers.

Interesting tidbit ... assume for the moment the OP was running the Lunati 712 cam in the ill-fated motor. With 1.7 ratio rockers his lifts were .606"/.623" (I/E). If the rockers were 1.8 ratio, .642"/.660" (I/E). If the cam was the 713 , then .634"/.640" (I/E) w. 1.7 rockers and .671".678" (I/E) w. 1.8 rockers.

Good point, however I believe this time 64speed is using the 041 cam with .470" lift (with 1.5 rockers). With 1.7 rockers lift would be around .533". Many cams have that lift with 1.5 rockers so I think this time he might be OK with those rockers. But I would not go that route. I would investigate the problem Gach mentions in post #1491. I believe Pontiac engineeers knew the limits of their block and didn't exceed the 1.65 ratio rockers. FWIW