I bought this timing cover (for $20 you can't go wrong) and after watching this YouTube video below, not sure if I should use it. At about 6:20 in he states that 71 and up covers have a 5/8 oiling passage. I believe I have the style cover on the right with the 1/2 passage. I have a '72 1241735 455 block. Do I have an older cover 67-89? The oil passage measures 1/2 inch but will it work on my mild build street '72 455? This is a budget build, aleady installed new oil pump gears, TA booster plate, TA oil preassure regulator and new crank seal so would like to use it if possible. Thanks Here is link to my motor build thread. http://www.v8buick.com/index.php?th...atibility-and-clearances.392011/#post-3470016 Link to timing cover I bought. http://www.v8buick.com/index.php?threads/455-timing-cover-20.388410/ Video that shows the differences. 6:21 in the video
You CAN make the 1/2" 67-70 cover slightly larger to 9/16" and it will be better but not ideal. Since you already have a 72 block, it has the 5/8" oil feed passage and the 5/8" pickup. You'd be better off locating a later 5/8" front cover to save yourself some worrying time. You can reuse the booster and new pump gears in the replacement cover. About the only way I'd use the 1/2" cover is if I had pre-5/8" block. I'd drill it from 1/2" to 9/16". Some folks have drilled all the way to 5/8" but it makes me nervous. Then, you could massage the 1/2" cover to 9/16" (only an 1/32" per side) and still use the large 5/8" pickup.
