After removing the head on my 48 Super six, I found a crack between the #3 cylinder and the adjoining intake valve. I did a liquid penetrant test on all of the similar areas and found another small crack in the #1 cylinder. I'm not too concerned about that one but the #3 crack extends down the cylinder bore a little past the ridge, and on the valve side, it goes through the valve seat. (See the attached photos)
I spoke to two different engine rebuilders and they both recommended a valve seat insert, which is kind of a no-brainer, but they also want to sleeve the cylinder. This kind of scares me.
I have a spare motor that supposedly had been rebuilt at some time in the past and then sat outside and was never used. I pulled the head off of it, and yes, it looks rebuilt but rusty now, On this second motor, there are cracks in 3 of these locations! I tried to pop the valves out to see if the seats had been replaced but they are all seized.
So I'm thinking this is a fairly common problem with these engines and someone out there must have had some experience fixing this. Ford flatheads tend to have the same problem.
Feeling inside the water jacket with a wire, it looks like the deck is about 1/2 inch thick where the crack is, so judging by the results of my test in the photos, I would have to say that I think the area is cracked right through into the water jacket.
Is there any point in even trying to fix this? The stitching screws I've heard about would probably do the job although I've never used them. Does anyone know what lengths they come in? I'm thinking they should be long enough to go from the cylinder right through to the valve seat.
Does anyone have any experience with repairs of this type? Any comments or recommendations?
Thanks Fella's!
Mike Patterson
Mike, this is very common on Narrow blocks. ['48-''50 ] Starting in '51, they relieved the block, which corrected a lot of the cracking problems.. You should find a picture or a '51-262 block to compare to, cut your block to match that relief, install a new valve seat and it will probably be fine. To expand on your question about a sleeve, yes, we have done this many times. Something you have to have is a good machinist. Drill and pin the block, install a new valve seat, and sleeve.The sleeve has to have a shelf to seat on at the bottom of the bore, and can not be too thick. Hudson used a 4 ring piston, and if sleeved incorrectly, will have interference with the ring groove. I hope this makes since to you. No worst than it appears in the pictures, you can probably get away with relieving the block, and new valve seat in both, and continue your build. As many on here can tell you, the deck of a Hudson block is almost an inch thick.
FYI
I would ensure the Water Distribution Tube below the valves is clean after your cracks are repaired. Ive had cracks repaired by a few different methods and never had a problem afterward.
Well, I've found a couple of photos of the valve area relief in a newer engine (308), which obviously is a lot less of a relief than the 7X, but no dimensions are given. It looks like about 1/8 depth of relief but this would widen the land area on the deck considerably and with a bit of radiussing, should really help to alleviate the problem in the future. I think it would be good to do this an all cylinders while I have the engine apart. I will pass your information on to my machinist. I might as well give him the piston and crank, just to make sure of the required dimensions. I really appreciate your advice Doug. Thanks
You know, it's tempting to just throw the head back on and continue driving it, but I know if I do, I will have worse trouble later. I will pull the tube, prior to any repairs and hopefully it will go back in OK after the repairs!
Thanks for your help Chuck
FYI
Not sure why you removed the head, but couldnt be because of the cracks which pronably been there for Yrs from aging iron and perhaps overheated a few times. If this Hudson is a Driver and not for Hi Per4f, only a Driver, with an Intake Seat crack, (which runs cooler than an Exh), I would lap the valves then re install the head with a new gasket. The cracks may never go any further, but I would ensure not to over heat the motor in the future. Flatheads like you mentioned are nortorious for dracks and according to their Web Site they only fix the major cracks leaving the tiny ones alone.There are products to pour in to seal tiny cracks for peace of mind. I like K&W Permenate Block Seal.... .
I pulled the motor out to redo all the seals and gaskets because it was leaking quite a bit of oil. The pan also had a serious bash which needed to be straightened out. The head was getting some antifreeze on top and I thought it might be cracked. I can't find any cracks but I am getting it magnafluxed this morning to be sure. I am suspecting a leaky head gasket. I had another head ready to go on, but I would rather stay with the original head if it's OK. It has a slight lengthwise bow on the gasket surface so I will get a skim taken off before I use it. The head bolts seem to be a bit loose in the holes, which concerns me a bit as well.
I do not intend to drive far and it will not be a hot rod, but it would be nice to go a few hundred miles at a time, to attend a Hudson meet or something.
As long as the motor is out do it right and freshen it up at a good machine Shop. You will never regret it..
Tell the machinist that all the parts are available thru the Club Suppliers because that sometimes bothers a machinist when taking on an antique job.
Yeah thanks Chuck. I got the original head magnafluxed today and it's a boat anchor - several large cracks that didn't show with a dye check, but lit right up with the mag. I have another head (a 1950 model with the machined ridges) and had it checked for cracks, and planed. ready to go on.
The motor shop declined to do a repair on my block because he thought that once .090 was removed for a cylinder sleeve, and whatever else for a valve seat insert he didn't think there would be much material left to work with. He was pretty sure he would only make it worse. I will have someone else have a look before I throw in the towel.
I'm running out of time now though. I will have to go back to work soon, for about 6 weeks. It will have to wait now till I get home again. Thanks again.
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