Water pumps

[TomC750]

Originally Posted by tubman

Arghhh. I wish you would have told us yesterday about your plans for today. Using a regular tap to chase flathead head bolt threads in the block is NOTrecommended. Those threads are cut to a different standard than normal so they will seal better (a bunch of the head bolt holes go right through to the water jacket). It's better to use a genuine Ford head bolt with 3 or 4 grooves filed in it as a chaser.


Not to worry, if you search the forum you will find sealers recommended that usually solve the leak problem resulting from this. If you still have leaks, there are several block sealing products that also work well.

Well, hard for me to believe I did any harm. The tap went in smooth and easy until it got past the reach of the bolt, then there was rust. I have forgotten my "class of threads", but I would expect the bolts to be in that class that allows for a close fit. We rebuilt a lot of flatheads back in the day, I never recall having a leak problem.