How about McMaster-Carr, put 3260 in the search box and then scroll to the bottom - maybe a No. 0 by 3/16" in stainless steel? Other possibility it seems to me would be to use a split roll pin (page 3216) in 1/16". That said, I think it would be easier to drill and tap three 6-32 holes right next to the freeze plug, and use a large OD washer to overlap the plug and short screw with locktite, rather than trying to angle drill the lip of the plug and into the block (I guess this has less chance of hitting water but seems much harder). Just make sure not to drill through into water, but if you do the locktite also acts as a thread sealer. This would be especially easy with the motor on a stand.
stage I cracking ? where?
- Thread starter norbs
- Start date
How about McMaster-Carr, put 3260 in the search box and then scroll to the bottom - maybe a No. 0 by 3/16" in stainless steel? Other possibility it seems to me would be to use a split roll pin (page 3216) in 1/16". That said, I think it would be easier to drill and tap three 6-32 holes right next to the freeze plug, and use a large OD washer to overlap the plug and short screw with locktite, rather than trying to angle drill the lip of the plug and into the block (I guess this has less chance of hitting water but seems much harder). Just make sure not to drill through into water, but if you do the locktite also acts as a thread sealer. This would be especially easy with the motor on a stand.
From looking at the thickness of material, 6-32 is way to big, i am thinking something smaller and bolting a piece of metal across the plugs, good or bad idea? Would this promote more cracking drilling the holes around the frost plugs maybe?
Robert Wilson
Member
- Joined
- May 26, 2001
Those are exactly what was in the block. Judging from the remaining hole size, the No. 0 is what was used.
So I guessed right on that size, and too big on the screws
. Norbs, I think using a large washer on each screw would be better than a strap going all the way across, but that's just me. The cracks I've heard about go horizontal roughly through the middle of the plugs, so how about using two screws, one at the top and one at the bottom so you avoid those areas?Here is a Theory for you Norbs.
When we weld a crack on a stressed piece of steel, we Drill both ends of the crack to prevent it from cracking again.
Why not Drill a hole beside both frost plugs, tap them to 1/4 pipe thread and install pipe plugs. that should prevent a crack in that area.
When we weld a crack on a stressed piece of steel, we Drill both ends of the crack to prevent it from cracking again.
Why not Drill a hole beside both frost plugs, tap them to 1/4 pipe thread and install pipe plugs. that should prevent a crack in that area.
Lee Thompson
New Member
- Joined
- May 24, 2001
What do you'll think about this?
Veeing out the crack--welding it up--machine 2 cold roll steel plugs the correct dia. for a slip fit in the freeze plug holes (1/4 in. thick) and welding them in solid. Seems as though that would help hold the block together. Also could hard block on the outer side of the bore.
Veeing out the crack--welding it up--machine 2 cold roll steel plugs the correct dia. for a slip fit in the freeze plug holes (1/4 in. thick) and welding them in solid. Seems as though that would help hold the block together. Also could hard block on the outer side of the bore.
AM i doomed now?
Ok, this is what i have done, i have drilled and tapped a hole in the center where they usually crack. I am also epoxying in the frost plugs. Did i create a weak spot now where i drilled it? Or did i prevent it from cracking like a few have suggested here. I need some opinons before i do the other side??
Ok, this is what i have done, i have drilled and tapped a hole in the center where they usually crack. I am also epoxying in the frost plugs. Did i create a weak spot now where i drilled it? Or did i prevent it from cracking like a few have suggested here. I need some opinons before i do the other side??
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Lee Thompson
New Member
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- May 24, 2001
?
IMO, if you tapped for a NPT, that will tend to spread the block @ the point where it tends to crack, when tightened.
IMO, if you tapped for a NPT, that will tend to spread the block @ the point where it tends to crack, when tightened.
The powersource book reccomends drilling and tapping the block drains in that exact spot.
I'm Sure Norbs wont overtighten the drain plug.
placement in the middle of the cracking area is the whole point, i have to think GM new of this cracking problem and the suggestion to place the Drain this high is most likely helpfull.
What is the worst that happens? it cracks anyway???
Lee Thompson
New Member
- Joined
- May 24, 2001
It might be expensive but what about taking a steel plate and maching the casting plugs out of it and leaving them attached to the plate at slightly narrower, like 0.005 narrow spacing or a 0.002 oversized plug and pressing that into the casting plugs? It would compress the area between the plugs were they tend to crack and also put hoop stress on the plug bores.
turbodave231
Moderator
- Joined
- May 24, 2001
I've been watching this thread, holding my breathe because I'm using an early 4.1 S2 block. 3-4 years and a couple hundred passes.....no cracks....not yet anyway.
I've done some research on cast iron welding. Very tricky stuff. Even the "experts" have limited sucess. I've been told the carbon content in the iron migrates out of the parent metal and pollutes the weld. The welding needs to be done with the casting preheated and the casting needs to be heated back up after welding. Stresses need to be relieved by peening or shot blasting................or it just cracks again.........which seems to agree with what everyone has said here.
Brazing on the other hand may be a better approach. The parent metal never actually becomes molten. The process is more like soldering than welding. Brass or bronze will take a beating and it can be strong. Maybe not as strong as uncracked cast iron.........
I think that if you can properly stop-drill the crack and prevent it from spreading, brazing may be the best repair. I'd probably magnaflux the area to be 100% sure you know where the crack ends. Cracks in cast iron are very hard to see without magnaflux.
Why not make an O-ringed solid steel or aluminum freeze plug that is thru bolted to a T-bar placed inside the water jacket? It might weep if the crack re-developed, but it sure as hell wouldn't blow out. IMO pinning a sheet metal plug just adds more holes in the cast iron and more stress risers.
I've done some research on cast iron welding. Very tricky stuff. Even the "experts" have limited sucess. I've been told the carbon content in the iron migrates out of the parent metal and pollutes the weld. The welding needs to be done with the casting preheated and the casting needs to be heated back up after welding. Stresses need to be relieved by peening or shot blasting................or it just cracks again.........which seems to agree with what everyone has said here.
Brazing on the other hand may be a better approach. The parent metal never actually becomes molten. The process is more like soldering than welding. Brass or bronze will take a beating and it can be strong. Maybe not as strong as uncracked cast iron.........
I think that if you can properly stop-drill the crack and prevent it from spreading, brazing may be the best repair. I'd probably magnaflux the area to be 100% sure you know where the crack ends. Cracks in cast iron are very hard to see without magnaflux.
Why not make an O-ringed solid steel or aluminum freeze plug that is thru bolted to a T-bar placed inside the water jacket? It might weep if the crack re-developed, but it sure as hell wouldn't blow out. IMO pinning a sheet metal plug just adds more holes in the cast iron and more stress risers.
That looks like alot of work Lee to repair. Hope it holds for you. The crack looks like to me be caused by vertical stress, up and down. Putting some plugs in that are solid might not help, putting the metal plate might help strengthen the overall area though. Brazing sounds like a good idea if it works?
Cryo
You think Cryoing a block would strengthen the molecular integrity and relieve structural stress between freeze plugs as it is $400 to do a block. Of coarse it would have to be done on a block prior to it cracking. Just a thought one could call one of the Cryo specialist and ask them if in fact it would alliveate this problem between freeze plugs. Expensive Stage blocks that are worth prophylatic cryo protection.
You think Cryoing a block would strengthen the molecular integrity and relieve structural stress between freeze plugs as it is $400 to do a block. Of coarse it would have to be done on a block prior to it cracking. Just a thought one could call one of the Cryo specialist and ask them if in fact it would alliveate this problem between freeze plugs. Expensive Stage blocks that are worth prophylatic cryo protection.
Lee Thompson
New Member
- Joined
- May 24, 2001
So far so good !!!!
7 WOT passes in the bottom 10s @ close to 140 MPH--no leaks and no signs of a crack coming back.
7 WOT passes in the bottom 10s @ close to 140 MPH--no leaks and no signs of a crack coming back.
