Limits of JB weld block repairs

[yoss]

Its almost summer again and I got some great help here last year , some of you might remember me as the guy who found bondo on his engine block. Anyway my jb weld repairs were not holding last summer , they kept failing and leaking and I think its because the lower part of the crack was pushed out when it froze - its on a flat part of the water jacket, probably a good 4 inches long - and no , no water in the oil.

Long story short can I hammer the lower part of the crack back into shape with the top or is this too dangerous for the casting , obviously I have nothing to lose but I'd like to hear the voice of experience before I try - should I heat it before hitting it ect - I know this/these questions come up REPEATEDLY and are annoying , so thanks in advance for your patience

 

[Bondo]

Re: Limits of JB weld block repairs

Ayuh,... I woudn't bother trying to bend it, more likely it'll just Snap off...

The Epoxy reair should work if you Prep the surrounding area...

 

[dieselram94]

Re: Limits of JB weld block repairs

I assume the crack is not in a spot where you could weld it? I have successfully welded a few cracks in blocks before.....I always preheated the area I was going to weld first with a torch and the welded the crack. I have also seen a product simmilar to jb weld repair cracked alluminum heads as well. This product is Marine tex and is sold in marine stores in various sizes. Hope you can fix it.

 

[cedarjunki]

Re: Limits of JB weld block repairs

have you tried reinforcing the jb repair with a piece of wire screen or mesh? or even a piece of a beer can.

 

[yoss]

Re: Limits of JB weld block repairs

from my limited understanding welding a cast iron block is not desirable, pinning would definitely not work without getting the jacket back into shape and I have read opinions that suggest a vortec 350's water jacket is too thin anyway - I am going to grind off whats on there now during the weekdays and then try to make a decision, I will probably end up trying to bash it back into place because after the trouble last summer I'm 9/10 of the way to buying a 400hp 350 (its a direct drive) from US Engine for 2,500 or picking up a core and building it up myself for the experience -

which by the way, are there any marine specific internals? My much more experienced mechanic friend said forged pistons and crank were likely

 

[bomar76]

Re: Limits of JB weld block repairs

1. There is no such thing as a vortec block.
2. The casting thickness is the same on roller/non roller, 2 piece and 1 piece main blocks
3. The marine specific INTERNALS are: camshaft, head gasket. That's it.

Your mechanic friend is full of it.

 

[zbnutcase]

Re: Limits of JB weld block repairs

Slather it with a GOOD epoxy, such as Marine-Tex, not JB Weld. JB good for small jobs, not so good for cracked blocks.

 

[billy4hp]

Re: Limits of JB weld block repairs

I have had the experience of repairing and modifying more than my fair share of cast iron blocks both aftermarket and OEM... Sometimes it's to repair a crack or to install oil return screens, magnet installation, dry sump fittings, etc..

The problem with most epoxy repairs are:

1. Incorrect prep

2. Attempting to repair the unrepairable (there are limits to what can be fixed)

3. Not allowing enough time for the product to fully cure

4. Using a product that does not match the expansion and contraction rate of the item being repaired


These guys produce one of the best epoxy repair kits IMHO...

http://www.miller-stephenson.com/

If you scroll down you will see a link to their epoxy kit, Miller Stephenson 907. You can order it direct from Miller Stephenson...

It has the closest expansion and contraction rate to cast iron that I have found and works very well in a "single sided" repair where the crack is on say the outside of a block and the repair would be unsupported versus a deck repair where the repair would then be sandwiched between two items...

JMHO...

 

[Lodgepole]

Re: Limits of JB weld block repairs

Whatever you do, don't try to hammer it back in line. You will end up with a hole instesd of a crack. Cast iron just won't bend twice.

 

[Fishermark]

Re: Limits of JB weld block repairs

I will probably end up trying to bash it back into place because after the trouble last summer I'm 9/10 of the way to buying a 400hp 350

Bash it and you will be 10/10 of the way to buying a new engine. It sounds like that's what you want to do anyway.

There is no way you will be able to bend it back into place. As mentioned above - either epoxy it again with some better prep... or go ahead and get your new engine.

 

[yoss]

Re: Limits of JB weld block repairs

You guys have convinced me I am going to pick up a core and rebuild or make a 383 out of it - I can seriously mate my vortec heads to any 350? I asked in here last summer and was told differently that I would need a vortec block for everything to work

 

[billy4hp]

Re: Limits of JB weld block repairs

You guys have convinced me I am going to pick up a core and rebuild or make a 383 out of it - I can seriously mate my vortec heads to any 350? I asked in here last summer and was told differently that I would need a vortec block for everything to work

I believe you are confusing a "Vortec" block (no such thing) with a factory roller lifter block...

And yes you can bolt the Vortec heads onto any year Generation I small block Chevrolet block without modifications.

 

[bomar76]

Re: Limits of JB weld block repairs

You guys have convinced me I am going to pick up a core and rebuild or make a 383 out of it - I can seriously mate my vortec heads to any 350? I asked in here last summer and was told differently that I would need a vortec block for everything to work

Again there is NO SUCH THING as a vortec block.

NO SUCH THING.

Question:
Is there a vortec block?
Answer:
NO

Vortec heads will bolt on to any 350 block
You need a vortec pattern intake manifold with vortec heads.

 

[Fishermark]

Re: Limits of JB weld block repairs

Vortec heads will bolt on to any 350 block
You need a vortec pattern intake manifold with vortec heads.

Don't know who told you what last year - but as mentioned above - you simply need a different intake manifold if you go with Vortec Heads.

 

[billy4hp]

Intake manifold for use with Vortec heads...

Intake manifold for use with Vortec heads...

Just an FYI on the whole intake thing, most well equipped automotive machine shops will have a steel template that allows them to transfer on the old style intake bolt pattern onto a Vortec head with a standard mill (Bridgeport)...

Shouldn't cost you more than $100.00 for a pair of heads...

Just wanted to throw that out there...

 

[yoss]

Re: Limits of JB weld block repairs

well fortunately I already have the vortec intake manifold bolted to my heads - but you guys have saved me a ton of trouble and money already because I might have bought an older block not provisioned for factory roller rockers

 

[Tommywalton]

Re: Limits of JB weld block repairs

I went through the same thing. Don't waste 2500 on a merc shortblock. Orielys sells 350 long block without core for around 1300. Swap parts, go boating. I went to a srapyard and bought a 350, swapped and ran all last summer for around 500. I have welded 3 engine blocks, all sucessful. No preheating. Rods for welding cast iron. I found that I couldn't travel too far once I started welding. 1/4 inch max. 2 of the 3 had no leak but 1 I could get it to seal. A coat of jb weld sealed it. That was 3 years ago and it still running. I left my cracks pushed out. it give u a little ledge for your weld to sit on.

 

[HT32BSX115]

Re: Limits of JB weld block repairs

Yes, I would not hesitate to replace that block with a wrecking yard truck long block....or just buy one new.....

some of you might remember me as the guy who found bondo on his engine block.

Well if that happened to me, I'd invite him in and offer him a beer!!


Cheers,


Rick

 

[Bondo]

Re: Limits of JB weld block repairs

Just an FYI on the whole intake thing, most well equipped automotive machine shops will have a steel template that allows them to transfer on the old style intake bolt pattern onto a Vortec head with a standard mill (Bridgeport)...

Ayuh,... I believe you're Wrong about that,...
The Intale ports on Vortec heads are about .200" Higher than the old style heads...
The intake ports of an old manifold, won't line up with, nor fully cover the Vortec head intake ports...

 

[billy4hp]

Re: Limits of JB weld block repairs

Ayuh,... I believe you're Wrong about that,...
The Intale ports on Vortec heads are about .200" Higher than the old style heads...
The intake ports of an old manifold, won't line up with, nor fully cover the Vortec head intake ports...

Bond-o,



Ayuh,.... Here ya go...


http://www.goodson.com/store/template/product_detail.php?IID=2954

Use a 1205 or 1206 Felpro intake gasket... Works just fine... Sure you might have to do some minor port matching but nothing out of the ordinary... In fact, most decent machine shops will scribe your intake for you as part of the procedure so you know if anything needs to be done or not...

I am not touting this as something that should be done with Vortec heads (there are some draw backs), but if given a particular situation where I had to use the old style intake and I had a pair of Vortec heads I would modify them in a heart beat...

The whole reason that Goodson even produces a plate is there are multiple "budget racing sanctioning bodies" that allow you to use Vortec heads but require a certain casting number 2bbl cast iron intake manifold from the mid 1970's to be legal. This modification of the Vortec heads has been done for years...

JMHO....