Block cleaning and magnaflux

[GOSFAST]

Originally Posted by Mn1949ford

Hey fellas- Can anybody recommend a place in Minnesota to get my flathead block cleaned and magnafluxed? I live between St Cloud and Princeton,but will drive as far as needed. Thanks

It needs to be pressure tested more than it needs "magging", pressure test shows everything?

Thanks, Gary in N.Y.

P.S. "Magging" is definitely OK though! Pressure test first, "mag" second! (Tip), whatever shop you choose for machining try to find one that has a block-plate to finish hone the bores?

[Tim Ayers]

Originally Posted by GOSFAST

It needs to be pressure tested more than it needs "magging", pressure test shows everything?

Thanks, Gary in N.Y.

P.S. "Magging" is definitely OK though! Pressure test first, "mag" second! (Tip), whatever shop you choose for machining try to find one that has a block-plate to finish hone the bores?

Gary is a pro and his advice is spot on. After going through four blocks recently, only thing I would add to his suggestion is this:

Clean it the best you can at home first before doing any tests. The fifth block that I wound up using had so much crud in the rear of the block, I literally could drive a long screw driver into the mass like a nail into wood. If I keep that crud in, I believe it would have sealed a leak while pressure testing.

When you are up and personal with the block, you can sometimes find cracks yourself before spending any money on any services. On two of them, I was able to locate cracks by eye.

Its a dirty job, but a necessary step. Use braided cable in a drill, screw drivers, coat hanger, or anything you can to get in there and clean as much out as you can first.
Having it on a stand helps because you can tilt the block to get the crud to fall either forward or back and you can vacuum it out with a shop vac.

Once you scrape out as much as you can, then have it pressure tested. I prefer to give it a quick cleaning dip before magging it.

If it all checks out, I highly recommend a bake and blast cleaning before the machine work starts to get any of the remaining crud out. After machining, it will need to be dipped cleaned again to get rid of the metal dust that is there. A rag cleaning doesn't always get off all of the cast iron dust left from the machining process.

Many steps involved but worth the effort and expense to ensure you have a good block before building.