Technical Would you run it?

Currently rebuildning a small block Chevy. Its a 350 thats being stroked to 383. Some days ago the shop contacted me. Due to worn cylinders we had decided to rebore the cylinders to 040.
The cylinders looking real nice. However in two of the cylinders two small areas with pores appeared during the rebore. They are located far down in the cylinders. Well below the rings. About an inch or so from the bottom.

My main concern with these are if there is a risk coolant leak or other problem? They are very small. Havent been able to see how deep yet.
By the looks of them them looks like casting defects in the sleeves.

At this point the block is more or less ready. The pores appeared while the last cylinders were rebored. So sleeving isnt really an option. As far as I see it I can either run it or find another block. Suggestions?

 

Those look like pin holes, and if sleeving isn't an option, I'd say get a new block.

 

is there coolant that far down in the block?

 

Being that low in the cylinder, is coolant going to be near them? A cylinder wall thickness checker should verify solid material or coolant p***age.

 

Looks like casting porosity where the section thickness of the iron changes. If its not in the area of the waterway it wont be a problem. Fill the block as much as you can and check for signs of wet.

 

We tried yo measure it and its right by the end of the water p***age. At very bottom really close.

 

Was considering to fill it up with water a bit and leave it for a few days. A leak would create a streak of rust quite quick I guess.

 

I would ask for your machine shops opinion...afterall, they will be the one responsible for covering the warranty.

 

I see you are in Sweden where there might not be a large number of replacement blocks available to you plus, it sounds like you've already spent the $$ in machine work on this block ... you could possibly use a product like Hard Bloc or Moroso Engine Block Filler and only partially fill the block, then use a coolant system sealer.

I have heard of people doing partial block fills on street engines so the block gets added stiffness but doesn't compromise too much of the cooling system. I have never done it, but it might be something worth looking into.

If I remember correctly, when doing a partial fill, one side is filled up to the bottom of the "frost/core plugs" then the engine is rotated and the other side is poured. Again, I have heard of it being done with no apparent affecting of street cooling but I haven't done it myself so I am definitely not speaking from experience.

 

We ran a lot worse stuff than that in log trucks

 

You can buy leak test die that will show up in UV light. Used for testing water systems.

 

They arent that uncommon. The problem is to find decent ones. Some years ago they were common and you could buy them cheap. Now its harder and most Ive seen are overpriced wrecks.
Its a shame this block has this problem since its a fourbolted one. Have another fourbolted 350 in the garage. That one is also in bad shape. Nasty crack on the side.

 

If it were my block, I would have it sonic tested to see how thick the sleeve is in that area. In lieu of that another idea is to pour rubbing alcohol into the block. Seeps through pits better than water and doesn't affect the metal. Just keep flame away.

 

Would it be best to check it under say, 20/25 pounds of pressure? Make up some plexigl*** plates to mimic the head bolt pattern, then plug and supply air through maybe the tstat housing? Plug the WP ports too.
Look for air bubbles?

I’ve heard about this for FH V8’s.

Edit: I should say I’ve read about folks doing something similar for the FH V8. But I don’t have details.

 

I'd use something like kerosene or diesel fuel. It creeps through tiny cracks very well . I've also used a long tube on an air-pressure gun to blow from inside the block against the problem area while squirting light oil or other liquid on the cylinder bore side. It'll bubble if the air gets through.
If those checks show no problems I'd run the block. I might even clean the pits out with a good clean solvent (paint thinner?) and work epoxy like JB Weld into the pits before honing. Some may laugh, but it works! The rings don't run down in that area anyway....

Terry

 

Would be a good idea to test it.

I've seen some engines run with pits filled in using JB weld in the areas where the rings contact. Even if these pits are leaky, there's gotta be a way to seal it up.

 

It will have to be tested under pressure, 25 psi. The area of concern might be below coolant but the defect may extend upwards into coolant p***age. You used the term sleeves, do you mean bores or is the block sleeved?

 

Is sleeving the two cylinders a possibility? HRP

 

I would test it under pressure before putting any more time into it. Might not leak sitting there but once it's at operating temperature with 15#s of coolant pressure it could be a whole other story. If a shop is building it then let them handle it and get paperwork for what they did...

 

Pressure test it. You will need one plate for the head surface and one for one of the WP inlets. Test each side individually. This is most like operating condition and the best test.
If this is going to be a big issue where you are, use alcohol or another smaller molecule liquid as mentioned. The shop may also have dye penetrant for cracks that could be poured into the water jacket area.
https://en.wikipedia.org/wiki/Dye_penetrant_inspection

 

X5 for a pressure test

 

Another vote for use of a block filler product, I'd use RokBlock epoxy since it is designed to expand and fill voids and crev***es and is water tight.
Stuff gets used all the time here in the states.
If your worried about cooling just do a minimal fill, just to seal up the bottom 1/2" of the block water jacket

Rokblock, Professional Engine Block Filler, 25 lbs. - Compe***ion Products

 

Why can’t it be sleeved?

 

I'm sure it could, but it has already been bored at least in all cylinders. Sleeving requires an overbore, a chilled sleeve and a warm block, then a press. This can and will distort the other cylinders, which is why it's always done before boring. In effect, it could easily take his 40 over bore block and turn it into a sleeved block that needs to next size up pistons and another round of boring. Time and money, along with it probably going to 60 over and that's often the limit.

 

Thanks for the input. Been looking around for replacement blocks. And its not looking that good. In the past these small blocks was one of the most common V8s in Sweden. You could find them more or less everywhere. Now they are becoming rare. At least decent ones. Many look like ****.

However Ive found one block. Its a four bolted truck block. 010 casting. Seems to be from a 1974 c10. The cylinder bores seems to be a bit rough. But its possible to rebore. Since I need 040 it has a bit of margin to it.
Its a couple of hours drive. Thinking about giving it shot.

 

How much power are you planning on? Do you really need a four bolt main block?

 

If I were a gambler I'd put my chips on that being a dry spot. I'm surprised nobody mentioned the quick obvious check. Measure the depth of the cooling p***age from the deck as close to the area as possible, then down the bore. If in the bore it's less than ⅛ I'd worry just a little. If it's further down the bore just finish the job. If there is any concern, yes a very short rokblock treatment will settle your nerves for good. No more than ½" or whatever the product minimum is if there is one. I've seen a lot worse win races all season long. Good luck...