Suedes Car Club
Tech Q and A => Running Gear => Topic started by: 31Rodder on May 08, 2007 6:55 pm
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is it possible to warp a block if the engine overheats? or is it just the heads?
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I would imagine you could warp the block. I would think tho, that having the deck planed may get you by.
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Warping the entire block is not that likely. However, it is easy enough to warp a local area in the block, because localalized hot spots will occur when an engine is overheated. Typically cylinder bores will warp, especially in thin wall castings of a Chev 350. A Chev 350 cylinder walls will range between 0.075" to 0.090" thick due to the draft required to pull the core during casting. If the engine is bored 0.030" over, the wall thickness can drop to 0.060". For all practical purposes, this is considered the limit for ductile cast iron. I have known a few people who have tried going 0.040" or 0.050" over on a 350, but the engine only lasts for a few thousand miles before the cylinder walls warp enough to cause a drastic drop in compression. It is also possible to warp bearing surfaces (Such as a couple of certain V-Twin's at work right now, but that is another post) if the heat is localized in that area. Flatheads are notorius for warping the deck and area round exhaust valves to the point of cracking, since that becomes a hot spot.
I apologize for the long, rambling answer. (I can't help myself)
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thanks for the replys
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30 over? Huh? ive seen 60 over 350s Run HARD for long periods of time with no problem.. the only thing ive heard about is not to go over .040 on a SB 400...
a 400 and a 350 is a the same bore centers..... im not 100% positive but a 400 is not all just stroke.. bore size is larger too...
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to repeat what rb said, you can totally warp a block. I believe .009 is the limit on flatness. Grab a straight straightedge and a feeler guage.
all first gen small block chevys have the same bore centers the 350 is a 4" bore, 3.48" stroke, the 400 is a 4.125" bore/3.75" stroke, and its f'd up that I remember crap like that.
how much you can bore a 350 totally depends on when the block was made and what the block was made out of. A 1974ish and earlier block had a lot more nickel in them and were thicker in some areas and could easily be bored .060. They also take a long time to rust compared to newer ones. The newer '80's blocks. . . i shrug my shoulders. I wouldn't trust them. Any new bowtie block from GMPP is also stout everywhere. The good news is you can sonic test any block and see exactly how thick the cylinders are on that given block. This info isn't from me, I soaked it up working at homerun racing engines in Alex.
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is it possible to warp a block if the engine overheats? or is it just the heads?
Why do you ask grass hopper ? :)