59A vs 8BA Block Cracking?

[Barn Junk]

Have dragged home, dissembled and examined a number of flatheads over the years. In my experience, I seem to have noticed that the valve to cyl cracks are more common in 8BAs than 59As. Maybe just because they operated in heavier cars?? Also the 59A factory relieved blocks are not usually cracked there.
Ran across some nice big bore pistons (+1/8 and +3/16) and am going to machine and assemble a few motors. Since I can use either type block, have others developed any preference as to what series of blocks might hold up better or are they all just a crap shoot. Does the relieving reduce hot spots and reduce risk?

 

[rotorwrench]

Relieving actually makes the block a bit more vulnerable but mostly if a person uses a crow foot chambered head design like a lot of aftermarket finned aluminum heads have to take advantage of the relief. The relief in truck engines actually was to drop the compression a bit to prevent the ping on the gasoline of the day. They needed all the help they could get back then. Its use in hot rodding was the hope that decreasing the chamber size and relieving would help with breathing flow but the help was limited and higher compression brings back the heat. Much of the cracking in the old engines was due to lack of maintenance on the cooling system. They can overheat for a lot of reasons which will cause cracking. Keeping up a cooling system with twin water pumps and antique type radiators takes a little more work than the modern stuff for sure.

Some folks prefer the 8BA block since it is more versatile for transmission changes and others prefer the 59 series for the nostalgia. Apples and oranges to me. There all good.

 

[tubman]

I've brought this up a couple of times on the H.A.M.B. because of my personal experiences. I have had 6 8BA blocks over the years and have never had one that was fatally cracked. Of the four I still have, 3 don't even have "part number" cracks; the other one has two out of the four possible.

However, the responses on the H.A.M.B. have almost all been the other way; 8BA blocks are more crack-prone, my experiences not withstanding. I like 8BA's because I am done dealing with torquetube banjo rears and full-floating bearings. This happens when one gets old.

So, I guess, the question is still "up in the air".

 

[scooder]

I gota say my experience is that 8BA style are more often cracked from valve seat to bore than earlier stuff.
Choice is yours really dependant on transmission choice, 8BA can be bolted to any transmission.
Martin.

 

[rotorwrench]

I think that time has clouded the issue of whether one cracks more than the other. When I was a kid, I remember piles of old flathead blocks setting in salvage yards that were cracked either due to overheating or freeze up. The numbers looked pretty even to me for both types. There were a lot of 8BA block type engines sold back in the 48 thru 54 time frame. That's 6 to 7 years of production with follow on production for spare parts. The 59 series was only produced from late 44 thu 48 so that's a marked amount less production. Most of the cracked 59 series were scrapped a long time ago and a few of those imediate post war vehicles ended up with 8BA engines in them.