My 27 block has a hair line crack in the top of the valve chamber between #2&3. It runs through the valve cover flange and up about an inch. The block and frame stamp match. I need to bore this block so is it worth repairing or is replacement best?
It can be repaired. I'd recommend cast iron welding it. It'll probably set you back $400. A different block will set you back for less money.
How about a picture? Sounds like it's not into the water jacket. Maybe it's not fatal. If you have the block welded you will likely also have to have it rebabbiited.'
This may help as a temporary fix.
It probably can repaired. I would get an estimate or two. Take some pics of it and send them to some of the repair shops that repair cracked blocks.
I would consider the cost of another block to the repair cost of your cracked block. Probably can find another good block but finding one with good Babbitt is another story.
You might want to consider metal stitching to save your number matching block.
We in New England are blessed to have a metal stitcher whose skills place him somewhere between Artist and Wizard. Much of the work which comes to him is routine and ordinary, but occasionally he repairs something with work that is nothing short of magical, and often at a reasonable cost in almost anyone's world.
As an example: a fellow in our club noticed a slight weeping of coolant from the center welch plug. Using the appropriate tools to pick and scrape around the plug in order to confirm a rusted out plug, he had a portion of the block from the welch plug to the valve cover flange and into the valve chamber FALL OFF!
Now, this was a rebuilt engine that he had been running for a number of years with NO problems. He had some money invested in that block: bored, new valves, pushrods, a few new valve seats, and of course babbitt. Needless to say he was crestfallen. Following the advice of club members he pulled the engine and brought the block to the Magician who repaired it. The repair was Beautiful; drag your finger tips over it and feel nothing, with a coat of paint it disappeared and it, of course, did not leak. The cost was something like $285.00
I hope that you can find a satisfactory solution to your problem. Good luck, Bill
The crack is in the water jacket. Here are some pictures.
I would find another block, I had one welded up form a professional shop and the estimate was 300. and when I picked it up it was 980. for it. That is a real common crack on 26-7 blocks, I quit buying them at auctions unless the valve door is open and the head is off, been screwed way to many times. You can knock the numbers off another block and restamp it and the only one that will no it is not original is you!
After completing a valve job and some other maintenance, I was putting the engine back together, attaching the water return hose to the elbow on the block when the entire area around where the elbow bolts fell off completely. Thought I was doomed as all number match on my 1914.
If I remember correctly, I posted this issue on the forum and, as usual, the help and suggestions was overwhelming! It was suggested I use something called Belzona. It's like a glorified J B Weld and, frankly, expensive. It's from the Rumford Industrial Group in Miamisburg, Ohio. Google it.
After very carefully cleaning and sandblasting the area, we mixed and applied this stuff, sort of embedding the two studs into the goop. Carefully following the directions.
The repair has been in place for just about a year now and it has been great through all last summers touring. No problems.
Hope that helps.
Are you sure it does not go to the port? Dan
Google " How to repair cracks in cast iron Gas Engine Magazine "
There are several methods discussed that you could do yourself.
Theses pictures show same crack and more. All can be readily repaired by metal stitching. I wouldn't advise welding since the water jacket on Model T is thin around freeze plug area.
I would check to see how many other cracks block has before discarding it. Good blocks are hard to find. http://www.jandm-machine.com/metalStitching.html