I picked up a flatty 8 this weekend and upon tearing it down i noticed several cracks,They're from the stud bolt hole to the water jacket between the cylinders in three spots. A friend who helped me tear it down said this was normal with flatheads, Is it normal? Can these be fixed?
I know that some can be fixed, but I think it depends on where they are. I am pretty sure that you are o.k. as long as they do not involve the valve seat. Don't quote me on that, but I think there is hope.
All three are in between the cylinders from the stud bolt hole to the water passage just underneath. They don't come near the valves or the cylinders.
Just "about" every flathead has cracks.. it only matters how many and big they are. cracks are normal. if you do a good job with the rebuild you should be ok. also post some pics of the cracks. 3 out off the 4 flathead i had, had cracks. Have some who knows about them take a good look at them and then judge it..good luck.bs
I'll try to get some pics of them this weekend(have to get batteries for camera) and post them. They're not big cracks but are noticable.
Definitely post some pics. If you have that many cracks, it may be cheaper to find a better block than to have the cracks repaired.
You rendering did the job. Both of the flattys I have had and some others I have seen have these same cracks. No big deal. As long as the exhaust and intake areas dont have cracks running from one to another and there is no compromise in the valve and cylinder area your ok. Now hurry up and get that thing together so we can see it.
just use a good sealer when you put any head bolts in to the waterjackets and they will seal up fine, copper coating on the gaskets will do the rest.
Those aren't cracks, they're stress relievers... Av Permatex or the gray non-hardening modern stuff Permatex has for fasteners into water--can't think of name. Forget smearing goo on antique gaskets, you can now get modern ones with the teflon or whatever mystery magic stuff, just like you'd use on a modern engine. Should help allow the heads and block to do their things as they expand and contract more happily. Studs: Do not tap holes, although it is quite likely they have been tapped by someone in the past 50 years--the block threads are extra-deep class three fit, and tapping with any normal tap or thread chaser will remove metal and leave studs very slightly wobbly--I always wondered about this as I happily ruined those holes in the past. Before final assembly, screw in studs just a little more than finger tight, mebbe 10 ftlbs, with your chosen goo on the threads, put on heads and gaskets, and tighten the nuts on to tight enough to force nuts square against heads but not enough to compress gasgets, and allow to set for a while. Assuming head surfaces and nut bearing surfaces are machined square to the world, this will help set the studs vertical so you don't have a struggle getting heads on and off.
Thanks for the info Bruce! Glad ya posted that cause i was going to tap all the threads before it went to my machinist.
Just cleanemout with gun cleaning brushes and carb spray, and tell the machinest to stay outta there too. Banjo rear axle bolts and holes are special, too--run a tap in there, and all the lube will soon be on the outside of the case.
i ,ve heard the same as the other guys...as long as the crack does not run into the valve seat od down into the cylinders it will propably be ok.. you might want to put a stud in the particular hole and use sealer on it before installing the heads..
Those cracks are so common they have a factory part number. Cracks from bolt holes to water holes can be ignored. Cracks down a cylinder can often be fixed and the cylinder sleeved. Cracks in the pan rail or main webs are terminal.
One of the first thing you should do after its relatively clean is presser check the water jackets. Its kinda rare but there can be cracks in hard to see places, like the exhaust ports. On the last one I did I had about 8 or 10 studs leaking water with Teflon thread sealer . I tore it back down and used permatex right stuff and it sealed up perfect, zero leaks.
Oilcan Harry hit it on the head... here is what i get from my readin' the center main web between the babbit and the main bearing area is a common crack place... NO FIXUM for that. gotcha a boat anchor. same on the pan mating surface. cracks around the jackets are common and so are jug cracks and valve/cylinder cracks... those can all usually be fixed. worst case have it sleeved and haul ass
So far those are the only cracks! I have to find the tool to get the valves out so i can get it cleaned and inspect it real good.
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