Tapping oil galley holes

[TripleJ]

My 428 block is just  about ready to go together. One of the last things to do is to tap the oil galley holes. Wondering if you guys are using tapered reamers or just the pipe tap alone? I have started one hole with just the tap and to get the hole large enough to get more than a couple threads on the plug you have to bury the tap pretty deep. The thought of breaking a tap in my block is enough to give me nightmares. Thanks.


  Joe Menard

[Rory428]

I have always just used  regular NPT taps, which fit the lifter feed passages perfectly, a bit tight for the larger galley plugs, but no problems. That said, if you are going to tap all the oil galleys for pipe plugs, you are not ready to start assembly after cutting the pipe threads. I always do any drilling, grinding or tapping of the block, before installing the cam bearings , and do a final thorough jet spray wash, and blowing out all the oil passages, and every nook and cranny before even thinking about installing the cam bearings and beginning assembly.

[blykins]

7/16" drill, with a 1/4 NPT tap.

[TripleJ]

I have always just used  regular NPT taps, which fit the lifter feed passages perfectly, a bit tight for the larger galley plugs, but no problems. That said, if you are going to tap all the oil galleys for pipe plugs, you are not ready to start assembly after cutting the pipe threads. I always do any drilling, grinding or tapping of the block, before installing the cam bearings , and do a final thorough jet spray wash, and blowing out all the oil passages, and every nook and cranny before even thinking about installing the cam bearings and beginning assembly.

Thanks Rory428, the block is totally bare, all machining is done, this is the last step before final washing.

[TripleJ]

The missing ingredient is drilling beyond the press in plug seat. A new 7/16 drill and tap, mission accomplished! Thanks for the replies .

 Joe Menard