How deep can you safely deck a block?
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From: Norton, MA
How deep can you safely deck a block?
I'm talking about a 400, with pistons that currently sit about .077" down in the hole.
I want to deck the top of each cylinder bank. The goal is to raise compression, I'm not going for any quench stuff, so I can mill the head bottoms slightly too.
For the cam I'm trying to run, I need to dump a bunch of that .077 height, like .040" or more, even if I advance it 4*.
The calculations I've done up to now include a .04" thick head gasket, but if I could only take off a total of .040" deck height (say, .02" off the heads, .02" off the block), I would have to go to a .021" gasket. I'd LIKE, therefore, to take out as much deck height as possible in iron, so I can run a normal thickness (cost) head gasket.
How deep can you go in a block before you hit water, get so thin you get temp issues, or compromise strength? Same for a head (open chamber, M head)?
Also, what's the general rule of thumb for how much you can take off without having to modify an intake because the heads sit tighter together now? Same question for pushrods since you can only shim the rockers to a certain point.
Thanks for any info you guys can give me, just brainstorming a little bit tonight.
AleX
I want to deck the top of each cylinder bank. The goal is to raise compression, I'm not going for any quench stuff, so I can mill the head bottoms slightly too.
For the cam I'm trying to run, I need to dump a bunch of that .077 height, like .040" or more, even if I advance it 4*.
The calculations I've done up to now include a .04" thick head gasket, but if I could only take off a total of .040" deck height (say, .02" off the heads, .02" off the block), I would have to go to a .021" gasket. I'd LIKE, therefore, to take out as much deck height as possible in iron, so I can run a normal thickness (cost) head gasket.
How deep can you go in a block before you hit water, get so thin you get temp issues, or compromise strength? Same for a head (open chamber, M head)?
Also, what's the general rule of thumb for how much you can take off without having to modify an intake because the heads sit tighter together now? Same question for pushrods since you can only shim the rockers to a certain point.
Thanks for any info you guys can give me, just brainstorming a little bit tonight.
AleX
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From: Norton, MA
Well I've thought about that, but these are already flat tops with just a 3cc valve relief.
A custom set would be a ton, and I don't know of anyone who makes any with domes. I could think about bushing in some 351C pistons I guess, but this wasn't meant to be a total rebuild, just top end.
I could also probably get my rods metalled up and redrilled slightly off center, to get the pistons to top out a little higher, but that's no great solution either.....
What's going on is I was supposed to get some Aussie heads in a trade from all the way back in April, and the guy finally pops em off his motor last weekend, and they're open chamber....... Needless to say I wasn't pleased, but now I'm just trying to make something work. The bottom of my engine is fine, and so is the top in fact, but this was gunna be a nice upgrade of my current open chambers.
A custom set would be a ton, and I don't know of anyone who makes any with domes. I could think about bushing in some 351C pistons I guess, but this wasn't meant to be a total rebuild, just top end.
I could also probably get my rods metalled up and redrilled slightly off center, to get the pistons to top out a little higher, but that's no great solution either.....
What's going on is I was supposed to get some Aussie heads in a trade from all the way back in April, and the guy finally pops em off his motor last weekend, and they're open chamber....... Needless to say I wasn't pleased, but now I'm just trying to make something work. The bottom of my engine is fine, and so is the top in fact, but this was gunna be a nice upgrade of my current open chambers.
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From: CASA GRANDE AZ
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Could you offset grind the crank some?
That would bring the pistons up at TDC. Perhaps with a moderate offset and a moderate decking job you could get the pistons up out of the hole?
just throwin' out ideas.
That would bring the pistons up at TDC. Perhaps with a moderate offset and a moderate decking job you could get the pistons up out of the hole?
just throwin' out ideas.
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From: Norton, MA
Border, yes I could either offset grind the crank or do essentially the same by offset resizing the rods, but like CJ says, that would just invite all sorts of other weird issues with clearance, balance, and strength.
I thought of sneaking up the main (crank) bore just slightly too (.1"), but that would screw up the timing chain, and front and rear seals.
And CJ, I know Tim Meyer's site well haha, but his pistons don't offer me enough compression. I'm trying to run a fairly long duration cam, and I need a static CR of over 10.5:1.
I thought of sneaking up the main (crank) bore just slightly too (.1"), but that would screw up the timing chain, and front and rear seals.
And CJ, I know Tim Meyer's site well haha, but his pistons don't offer me enough compression. I'm trying to run a fairly long duration cam, and I need a static CR of over 10.5:1.
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yep longer rod will give you more compression, with the same bore/stroke/deck height.
I'm "told" that a 350 rod or even one from the 360 (mopar) will bump up compression... just to throw something else into the mix for you - why not leave compression down and throw 10psi on a blower at it instead? nothing beats blower whine!
I'm "told" that a 350 rod or even one from the 360 (mopar) will bump up compression... just to throw something else into the mix for you - why not leave compression down and throw 10psi on a blower at it instead? nothing beats blower whine!
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