MTFCA Forum

I found a real mag testing unit in all my parts a couple weeks ago and had fun with it today after I got some yellow mag powder in the mail. The flywheel I was going to use had a crack from one of the pins all the way to the center. I have three others that are ok.
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All 4 of my brake drums have cracks on every single one of the bolt holes. All 4 of them...
. .and then after soaking my Ricardo head in Zepp solvent for 4 days, I uncover this amazing "Fix". There's some work to do for sure... it took some time to uncover it and clean all the epoxy away, but I now know why this head was leaking in a mysterious way... I see some silver braising to fix this in my future. I found this product that looks interesting
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All 4 of my brake drums have cracks on every single one of the bolt holes. All 4 of them...

Check your other drums closely, especially reverse. It's rare to find one of those that isn't cracked.

Jeff, do some google searching on 26/27 brake drums with cracks there. Mine has the same issue. Some have suggested that this could have been that way for many miles/years even from new because of the thinness of the area. I chose to use the one I had. The drive plate is held by the drum so unless it blows the sides of the boss out, it is not going anywhere. Now a cracked low or reverse drum, different story. If you have a better brake drum, by all means use it.

I carefully checked each of the other drum's webbing as well as the drums themselves and all is good. So interesting how things you can't see with the naked eye come screaming forward with the right tools. Talk about an education!

Jeff

jeff- those cracks in the brake drum can't go anywhere- use it.

Dan

Dan McEachern wrote: ↑

Wed Oct 09, 2019 12:31 am

jeff- those cracks in the brake drum can't go anywhere- use it.
Dan

Thanks Dan. I'm getting that same info from asking around. I'll find the best one and use it.

Major bummer today... I got the block back from the machine shop and it was cracked in several spots. Luckily I have 2 more. What a pain. Uncertain if it happened pre or post boring, but from the looks of the cracks I'm guessing pre.

The next block I magged myself before I dropped it off. I'm glad I figured out how to use that giant mag coil and got the right ferrous powder.

Boy, this stuff certainly can test one's patience... but keeping it in perspective, these are 100 year old cars. And it certainly is an education.

Is this block even savable? Sleeve the cylinder and put in valve seat inserts?
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Yes the block could be saved. Might look into having the cracks pined then install valve seats and sleeves if you really want to save the block. One of my exhaust has a crack that runs almost to the outside, been running it that way for years. One of the reasons I put the overhead on, but am running stock head for now.

The cracks going to the outside- just pin them. The crack to the cylinder wall- normal practice would be to pin it and then sleeve that cylinder, as I'm not real fond of a pin in the ring travel area, but given how much these get driven relatively speaking, pin the end of that crack as well (there is no water in that area) and put valve seats in. Late blocks are still plentiful enough that its not really worth sleeving it unless you have a good reason to. Looks like you may have needed a seat in one anyway, and that should have been done before surfacing. Just my opinion.

Since you got a whole new box of powder, there other places on the block to check. Call me if interested, I'm not into a lot of typing on my tablet. Others may chime in.

Andy

Andyclary wrote: ↑

Thu Oct 10, 2019 7:59 pm

Since you got a whole new box of powder, there other places on the block to check. Call me if interested, I'm not into a lot of typing on my tablet. Others may chime in.

Andy

My check was cursory only. The machine shop you recommended did a full mag on the block this time before they bored it today. Not sure why they didn't the first time of the first block, but that's water under the bridge! It'll be done tomorrow.

Jeff