[White Lightning]

Hey guys whats your opinion on running a bbc with a crack running between the water jacket and the back head-stud hole? Ive heard it can cause hydro-lock and then its a serious problem if your driving. If that is the case whats the chances of it happening; just looking for opinions on the matter, i've heard some guys wont touch em and others build them like the cracks were not even there.

 

[Busted Knuckles]

In order to cause hydro-lock, it's going to have to get through the fire ring around the top of the bore which is nearly impossible. This sounds a lot like the same thing that appears on almost every SBC 400 block. As long as it's between a coolant hole and head bolt, run 'em. If it's between the coolant hole or head bolt hole and the cylinder, it's junk.

 

[White Lightning]

Thanks for the input, haha just looking for reassurance

 

[BillK]

Bob,
A picture of the crack would be helpful. One of the problems when they crack this way is that the bolt hole tends to expand when you tighten the bolt or stud.

 

[SMALLBLOC]

Moroso ceramic seal will fix anything but a broken heart

 

[kirkwoodken]

The first thing I do with ANY crack is to drill a hole at the end or ends of it to keep it from spreading. What size hole will depend on what you are working with. If you can't drill a hole, grind or make a radius at the end of the crack with a rotary file. That's the way the window crack repair guys do it, by drilling a hole to keep the glass crack from spreading, then seal up the hole. How you seal the holes is the same as how big of a hole you need to drill. Depends on the material and the damage. However, the pros often use "stitching" and it works very well, IF they are not starting their learning curve on your part. (This means you most likely need to find an old person.) http://www.locknstitch.com/metal_stitching.htm Just about anything can be fixed by a person who knows what he/she is doing. Fixing cracks is not an art form, but it does take knowledge and experience.

When I worked at Cupples Products, our 3600 ton extrusion press developed a crack in its cylinder. An outside company was called in to repair the crack and it was repaired as explained above, Drilled holes at ends of crack, stitched and welded. The cylinder was refinished with something that looked a modified floor sander. When done, it worked like new. Had roughly a 40 "bore.

If there was ever a block that should have been made with blind head bolt holes, it's the 400. If Duntov would have had his way, the '63 Corvette would have been a Rochester Fuel Injected 400SB. He couldn't sell it to the bean counters. Could have had an OEM 500+HP SBC Corvette in '63. Think how that would have changed things for the Ford and Chrysler camps.

Like Mr. B. Knuckles says, if the crack breaks into a thread hole, that hole supplies the radius to keep the crack from spreading. No problem. Put an extra drop of gunch around the crack and on the threads, and put it back together.

 

[White Lightning]

The blocks at the machine shop getting head work so i cant get a pic right now, the crack is running from top to bottom of the hole maybe half-inch of iron. I dont think its gonna get worse but as mentioned above i was concerned about the metal heating up causing the hole to expand which might let the stud lift some. Is it possible that it could lift enuff for water to be drawn through the gasket and head?

 

[engineguy]

Bob,
Have the block repaired with the locknstitch process, as Ken has suggested. This method is used successfully quite often in the heavy duty industry, where a bare block for an engine such as Caterpillar might run $10k or more. Then look at the bolt threads very closely, as you might need to repair/replace the threads too.

 

[White Lightning]

where would i get this done at, machinist shop or where? Any ideas on how much a repair like that would cost?

 

[Bob Tiley]

our local machine shop welded up my buddies 440 mopar block half way across the lifter valley and then bored it. The engine ran great for years. You need to preheat before welding and know what you are doing. At my last job we used to weld 2000 lb cast iron forklift counterweights to the frame. Preheating to 600 f then stick welding.

 

[engineguy]

where would i get this done at, machinist shop or where? Any ideas on how much a repair like that would cost?

Check your local automotive machine shop, they should be able to do it, especially if they do any heavy duty engine work such as Cat, Cummins, Mack, Detroit Diesel, etc.

 

[BillK]

Bob,
Loc N Stitch makes a thread insert called a "full torque" http://fulltorque.com insert that is supposed to be able to fix these types of cracks but .... The installation process is VERY critical. I am getting ready to buy the kit to do a few 400 blocks that I have that have the typical cracks from the steam holes to the bolt holes. After a long talk with the guys at L&S they recommended not to try using thier stitching pins, but to use the full torque inserts instead BUT .... he told me that you pretty much have to do them on a Bridgeport in order for them to be a successful repair. I hope they work ok as I have three 400 blocks that I would like to save.

By the way, this entire thread is speculation without some pictures

 

[GOSFAST]

I believe the crack the poster is seeing is the same one we've seen over the years on at least 1/2 dozen builds? It's actually quite common!

If it's the one in the photo below, we've established the fact that is a "non-issue" and has no adverse effect on the build and will cause NO issues down the road.

Thanks, Gary in N.Y.

P.S. Here's a shot of the last one out the door a couple years back! It's been running for some time now!!

 

[White Lightning]

the picture above is the crack im dealing with thanks for posting.

 

[rustbucket79]

I've seen the same thing, maybe 1 in 20 blocks I've seen it. I've always attributed it to impacting out that head bolt where it has some corrosion on the tip, spreading/loading that area like a wedge as the bolt backs out. Shouldn't be an issue.