V8 crack problem

Mbetti

Mbetti

Junior Member
Building a 8BA. I magnafluxed the block tonight and found some deck cracks I am not real concerned about, but I did find one from a pan rail bolt up the side a little ways then sideways 2 directions, T shaped. I suspect this is from freezing. See pic. Appreciate any input. Weld? Pin? Ignore? Junk?
Mike
 

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I'm no expert, but I'd try to get that fixed, Over 50 years ago, when they were hard to find, someone gave me a SBC block that they'd let sit outside with water in it and it had worse cracks than this on both sides. I brazed the cracks up (to stop the water leaks with no thought to structural considerations) and it was still holding when I sold the car it was in.

There was a thread on here or the H.A.M.B. in the last couple of months where someone finally tore down an engine that had served him faithfully for many years and he found about 2 feet of weld bead down by the pan rails.

Edit : Found it. Look at post #62 on this thread : https://www.jalopyjournal.com/forum/threads/after-25-years-its-time.1048439/page-3#post-12272928
 
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John R said:
Ignore is not a viable option. Weld or pin.
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My experience with pinning leads me to say- don't try to pin a real long crack in thin cast iron. If you preheat real well, maybe you could weld. If not preheated and cooled slowly, you may find yourself chasing more cracks.
My bet is brazing.

Karl
 
Find someone that is not a wimp about TIG welding cast iron with steel rod. Preheat and peen as he goes an inch at a time.
 

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Im the guy with 2 feet of pan rail weld. That crack is not the worry. Pressure test the block and look for more cracks in the exhaust ports that you cant get to....
 
Thanks for the replies, but things go worse in my mind. How about this crack for welding?
 

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If you can't get it welded , try the vacuum J.B Weld trick, I ran one for over twenty years by making a pressure test device and vee the crack and clean it with a good solvent or degreaser type cleaner. install the pressure test tool , (I used a cylinder head and made a gasket from neoprene) made a waterpump block off plate and used a air cond. vacuum pump to pull the J.B Weld into the crack, release vacuum and smooth over area. let set for a couple of days. Machined the block to max bore, stroked the crank, Then Ran the hell out of it for twenty years, blew the rods out of it trying to out run a 67 ford mustang.
 
What can be seen is one thing but what can't be seen is another. A person could weld up all the visible cracks and then find out there is a crack inside the center exhaust port. One with multiple cracks or spider webbing is still a reject in my book.
 
I had a 90 Olds with the 307. I hated that car and let it freeze up. Both sides of the block cracked from deck to pan. I Vee'd the cracks and made continous welds with cast rods from top to bottom. It ran fine and gve no problems for several years after. I took nothing loose on the block.
 
Both those cracks mean they are junk. A flathead is an intricate casting and those cracks are indicators of more damage that you won't be able to get to.
 
If you have all those cracks on a single block - I wouldn't screw with it . . . just find another. Who knows how many more there are to deal with.
 
on my original block the was a crack going from the cylinder to inside the valve port
& it was pined all ready I have taken six 8BA apart to find one good one

























7
 
Mbetti said:
Thanks everyone for the direction......junk it is!
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If I were you, I wouldn't scrap it until you have it's known good replacement sitting on the shop floor! Even then, don't scrap it unless nobody else wants it. For free even.
 
Capn John said:
DON'T JUNK it someone can use it!!!
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I agree! If nothing else, use it to practice your porting skills!

Back in the day, during Minnesota winters, we poor folk who drove cracked flatheads used methanol based antifreeze. It leaked into the oil, true, but evaporated out when the engine warmed up, plus it did not eat bearings like 'permanent' antifreeze would. If you had a real bad leaker that sat a few days without running, you crawled under before starting it and loosened the drain plug to let the accumulated antifreeze drain out of the pan.
If the heater started blowing ice cold air, you knew the radiator was so low the coolant was not circulating so you just stopped and topped it off.
 
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