stage I cracking ? where?

[Reginald West]

I have not pulled it apart since it was welded but I do look at it often and so far it looks good.The welder I used (like all of them claimed that he is a guru)anyway he said he used a real low heat and a high copper content rod. I think having the hard block in it takes a lot of the strain off the block and makes it much more ridged.

 

[750H.P.V6]

I tried to weld repair mine twice and it cracked again in short order both times. Later on it cracked in the same place on the drivers side too. At that point I scrapped it and started over. I agree with Reggie that the hard block might help out with block distortion and minimize any further cracking if the block is already cracked as well as keeping it from leaking also.

Neal

 

[Lee Thompson]

?

Norbs

Pin those freeze plugs. My stage 2 block cracked between the freeze plugs and like Jeff and Neal the plugs came out at the top of the track.I filled the block with hard block and pinned the plugs. That was 2 years ago and the motor is still running strong and it does not over heat.


REG

Not trying to start anything but how do you know that it does not overheat. The water should run the same temp as before--I can see where the oil might run a little hotter but what about the area of the cyl. bore that gets no water or oil to carry the heat away. You basically have a hunk of steel with no provisions for heat tranfer.
I have a crack in mine from freeze plug to freeze plug and have thought about welding--hard blocking--pinning--epoxy or all of the above.
I have heard many times of hard blocking and it still runs cool but if you think about it there is no reason the water should run any different assuming the cooling system is up to snuff.

I'm thinking about laying it on an angle and hardblock up the out side just above the freeze plugs leaving the inside to be able to get water. Then again how is that going to affect the bore with one side cooler than the other.

Food for thought.

 

[Reginald West]

Lee
My block is filled just above the freeze plugs the water flows through the block around the upper hafe of the bore. I am told (and I think its right) that most of the heat is in the upper hafe of the cylinder and the heads. The reason I say it does not run hot is I don't see water temps above 200 degrees and when I torn the engine a part there was no hot spot on the cylinder walls or pistons. I don't drive this car alot on the street but drive it around in 100 degree weather once in a while.

REG

 

[Lee Thompson]

Good info

Lee
My block is filled just above the freeze plugs the water flows through the block around the upper hafe of the bore. I am told (and I think its right) that most of the heat is in the upper hafe of the cylinder and the heads. The reason I say it does not run hot is I don't see water temps above 200 degrees and when I torn the engine a part there was no hot spot on the cylinder walls or pistons. I don't drive this car alot on the street but drive it around in 100 degree weather once in a while.

REG

I have to do something--WAY TOO MUCH $ in this piece of iron to toss it. Thanks

 

[Underboost]

Reg,

The only time to use "hard block" is before the machine proses right?
Otherwise when the "hard block" hardens it will change the shape of the block
do to expanding concrete. Correct? :smile: Just my 2.

 

[norbs]

If anyone can find a pic it would help me alot to see where to apply the epoxy/metal re-enforcements etc?

 

[Lee Thompson]

pics

Here you go--minus freeze plug that left @ 3/4 track.

 

[norbs]

That is pretty sick, how thick is the material where the crack is roughly? Notice that the casting around the frost plugs is not centered around the hole? Maybe that has something to do with it? I will look at mine right now.

 

[Mac in SD]

I seem to remember our local machine shop saying that threading the holes for pipe-thread plugs helps a little bit with strength in that area. Many aluminum block Chevy V6's he built had them, as well as SCAT blocks. Anyone else have an idea on that?

 

[CTX-SLPR]

It would add compressive hoop stress the same way an interferance fit fastener does. It works on aircraft fasteners, but they don't see the thermal loads that an engine block does. I think its worth a shot, not likely to hurt. The TA blocks use them and I've seen kits to do it too.

 

[Lee Thompson]

That would be great

I seem to remember our local machine shop saying that threading the holes for pipe-thread plugs helps a little bit with strength in that area. Many aluminum block Chevy V6's he built had them, as well as SCAT blocks. Anyone else have an idea on that?

If the current hole was sized for a NPT thread--best I remember it is not as I checked last time my block was out. It would have to be somewhere in the 1--1-1/4 in. thread. Pipe is measured I.D.

 

[750H.P.V6]

Lee,

Is your block a 3.8 or a 4.1? The reason I ask is that the 4.1 block should hold up a bit better if you end up going with the hard block. Welding the block won't hold, you might want to try brazing it up. Pinning the crack will keep it from leaking but it will still be cracked so you've compromised the strength of the outside wall of the block.

On my 3.8 liter block the crack continued to run after cracking between the freeze plugs. It ended up about 2" long on either side with one end of the crack heading toward the flexplate and one end heading toward the motor mount. Like I said above it cracked on the drivers side after that and then cracked horizontally in the #4 cylinder approx 1/2 " below the deck surface.

Sorry for the bad news.

Neal

 

[norbs]

So why build a stage I if its weaker than a 109? You know how much $ i have into this thing? Is it doomed?

 

[CTX-SLPR]

Don't know why but the 3.8L Stage I blocks have a reputation for doing this for some reason. I think the main reasoning is the 14bolt heads over the 109's. I think the 4.1L Stage I blocks are less prone to cracking between the plugs but I'm not totally confident in that. If you think you have a lot of money in this block, you should see how much is in my Production 4.1L. It might be less but its potentially a bigger gamble.

 

[Lee Thompson]

Neal

Mine is a 4.1 Stage II--early unit--takes a Buick rear seal--POS ever since I purchased it. Mine is also cracking past the plugs. Right now, just rearward.Thanks for the info.

 

[750H.P.V6]

Norbs,

I 3.8 liter Stage I blocks aren't any different that the Stage II blocks of the same vintage. The 4.1's will tolerate more abuse for a longer period due to being a stronger design from the outset. The siameesed cylinder casting ads structure to the block and the additional displacement is an added bonus. I know Reggie's block was a 4.1 and Lee's is also so they're not infallible either. Basically if you buy a used block, crank, or set of rods there's no telling what it's been subjected to prior to you owning it. I wouldn't tell you your project is doomed but at least now you know what to look out for.

Neal

So why build a stage I if its weaker than a 109? You know how much $ i have into this thing? Is it doomed?

 

[geno]

Ive got my 4.1 Stage1 block in the office and was thinking about making a table out of it Cracked in 3 places

 

[Reginald West]

Originally Posted byUnderboost
The only time to use "hard block" is before the machine proses right?
Otherwise when the "hard block" hardens it will change the shape of the block
do to expanding concrete. Correct? Just my 2.

Yes if your going to bore the block I would fill it first.However I did not bore mine the right after I filled it I ran it for about 9 months with just honing the cylinders and using the same pistons.At the cost of machine work and new pistons you might want to try it that way before you invest in all new stuff.

NORBS
I have looked everywhere for pictures of the pinning process but I have found none.Its almost impossible to get pictures with the engine in the car.

 

[Robert Wilson]

0153

My stage 2 block had small spiral shanked rivets, 3 per plug, pinning them. The holes drilled for the rivets do not penetrate water jackets. I threw them away after removal because I damaged most of them. I looked for a picture from several rivet web sites to show without luck...
I was planning on not pinning the plugs when I complete my project but you guys have got me scared. Anyone ever crack an 0153 stage 2?

thanks,
Robert