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Block filler

3K views 6 replies 7 participants last post by  johnsongrass1 
#1 ·
I have a 400 SBC that didnt clean up at 40 over and my machine shop went ahead and bored it 60! I know that usually this is a no no with these siamesed blocks but he assured me that this was one of the thicker blocks and it would be ok for mild performance without NOS. (it wasn't sonic tested) My question is... would it stiffen the block and strengthen it if I gave it a partial block fill? Anybody out there put block filler in for street use?
 
#3 ·
filler

You can't add the filler after the machine work was done. Most of the times it will distort the bores. If the block was not sonic tested it's a crap shoot on how long it will last....... There are under cuts that run along the side of the bores on these blocks and some have been reported to be as thin as .100" I would search out a shop with a sonic tester and pay the $$$ and have it checked before i go any futher. If you decide to take a chance and run it the way it is " DO-NOT" let it detonate.....

What are your plans for this motor,compression,cam, heads, nitrous????

Keith
 
#4 ·
I have run block filler on a few street strip engines.As a matter of fact that is the only engines I have used it on.I have done a few half fills to save a block.With the half fill,the engine wont run much hotter then without the fill,or might not run hotter at all,but I would have liked to see the bores finsihed with the filler in place.I will usually plate hone the cylinders after filling on a block with non fresh bores.I only do this when I want to salvage a race block for a street project.I cant get a good 454 core around here for less then $600,and that is for a smoking pile of dung.I have scored a few 454's with cylinders blown out from thrown rods and such,and I will take one with otherwise decent bores,and fit it with a sleeve or two,then half fill it if it looks like the damage went into the water jackets.This works on any engine,but it mostly worth the effort with bigblock since the cores are so expensive.I scored a thick wall 454 4 bolt that was .060" over,zero decked and align honed with a hole in one cylinder fo $50,and I spent $125 on the sleeve,100 to rehone it,and $50 in filler and supplies and I had a $1000 engine block{including the value of the machining} for about $300.It is running in a daily driver street car right now and doesnt show any signs of problems.I filled that one with about a little under 2" of filler.It also helps to run an oil cooler.Good luck.
 
#7 ·
If you decide to fill after the machining you need to use the cheapo cast iron rings. They will seat better and last longer than the moly rings. The filler will distort the bore when curing because the stuff expands. Hence the need for a cheapo ring which will seat faster and seal better due to their natural ability to compensate for roundness. If you were to use very stiff moly rings you would have a higher leak down percentages, possibly even ring flutter if all went wrong.
 
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