SBC block filling ?

[Reed Granrt]

Originally Posted by randy wilson

I see no advantage to filling any block. When we used to do it on stock blocks, not one rebuild were the cylinders round. Quit filling, and everything stayed straight. The stones just chattered after a teardoiwn using hardblok.

Randy
I would like to address this with my opinions and observation. Filling a block is a lot like purchasing a new block and putting it into service and is a lot like pouring new concrete. Lets address each one individually. If you purchase a new block, lets say a Dart, it will take a couple of tear downs and re-hones to get the bores to stabilize as the block has to go thru a "settling & curing" time. The aspect of pouring the block goes thru much of the same process as concrete. It will take that pour a couple of tear downs and re hones to stabilize also. Where I have seen definite advantages is where the block cylinders walls are thin and flex in the every firing pulse. I feel the poured block is a definite advantage but I also feel is does have a disadvantage. And that is the poured section runs at a different temp than that section with water going thru it, therefore they are 2 different dimensions. I have found that there is a definite small taper from top to bottom as a result of that temp difference. Most good machinist and racers know how to minimize that problem. Is the filler material a temp stabilizer? Not in my thought process. On any given run, the temperature in the block will begin to climb and will continue to grow thru the run. The filler material will continue to increase in temperature but the water cooled section will hit a maximum and then water will begin to cool it or stabilize it. This is not a perfect world, but with stock blocks, sometimes it is a necessity. There is another plus of a poured block over a stock block and without any doubt, the filler adds rigidity to the block. No doubt, in my mind, it strengthens the bottom end in the crank area. Is there a definite advantage to a poured block. I feel you have to look at each situation. A 9 to 1 motor doesnt need it as much as a 12 to 1 motor does and it goes on and on. But I feel if you do indeed pour a block, then by all means try to cure it after the pour for it to stabilize and shrink as much as possible before you machine it.
And I most certainly agree with Carl, that I never like a poured block over most after market blocks but as we all know, some manufactures do not have the advantage of an approved after market block and are forced to work with what they have and improve it any way that they can.
Hey just my thoughts.
reed

[carl hinkson]

Originally Posted by Reed Granrt

Randy
. If you purchase a new block, lets say a Dart, it will take a couple of tear downs and re-hones to get the bores to stabilize as the block has to go thru a "settling & curing" time.

And I most certainly agree with Carl, that I never like a poured block over most after market blocks but as we all know, some manufactures do not have the advantage of an approved after market block and are forced to work with what they have and improve it any way that they can.
Hey just my thoughts.
reed

We have refreashened a lot of circle track engines using Bowtie and Dart blocks and so far have not seen any problems with cylinders being out shape during the rebuild, I would think if we had any issues we would see it on a leak down test or blowby out the breathers.

I don't know how pouring a block will make the bottom end stronger as it has nothing to do with the main webbing. Adding splayed caps will strenthen the bottom end!! as it ties the main webbing in with the pan rails.

The poured blocks we have seen where the pour stops show alot of wear as the bottom of cylinders do not come up to temp like the top of the cylinders do.

We sonic test all our blocks be fore any work is done and go from there!!!

[Dwight Southerland]

Originally Posted by Reed Granrt

But I feel if you do indeed pour a block, then by all means try to cure it after the pour for it to stabilize and shrink as much as possible before you machine it.

X2

Use some good telemetry and find out the difference in temp of a filled block (the metal part, not the water that is circulating) at the bottom of the stroke and at the top after some hard runs. That will tell you much more than all this theorizing. I do know that a BBC early 396 block has an entirely different temp pattern than a sleeved 454 service block.

[396chevy]

Originally Posted by Dwight Southerland

X2

Use some good telemetry and find out the difference in temp of a filled block (the metal part, not the water that is circulating) at the bottom of the stroke and at the top after some hard runs. That will tell you much more than all this theorizing. I do know that a BBC early 396 block has an entirely different temp pattern than a sleeved 454 service block.

Yep, For sure!!