Compression
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Joined: Jan 2004
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Originally posted by scroob
And please don't call it a 400M. There is no such motor. The M designation is for the 351M only.
Put a Crane 268H cam in that 400 and I bet it would come close to the 460.
And please don't call it a 400M. There is no such motor. The M designation is for the 351M only.
Put a Crane 268H cam in that 400 and I bet it would come close to the 460.
just different crank and pistons everything else is identical
some people call them 400 cleavelands wich is not rite
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Joined: Nov 2003
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Thanks guys for al of the comments and suggestions. I think I will remove #1 intake and exhaust rockers and measure the travel. If I use an old pushrod I can put score marks on it for high and low then remove it and get a good measurement using the calipers. This way I won't have to worry about the rocker ratio or hydrolic lifter collapsing and I will have the proper geometry.
OK, I know better than to put a "M" after 400. What was I thinking? Must have been too much exhaust
OK, I know better than to put a "M" after 400. What was I thinking? Must have been too much exhaust
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From: Pryor
The most accurate way would be to use a dial indicator over the rocker tip. Then divide by 1.73. You wouldn't have to disassemble anything to do this. If you want to take off a rocker arm you could measure the lobe directly using a pushrod and a dial indicator. You could even throw a degree wheel on it and see what the duration of the cam is.
BTW, cranking 110 or so compression tells me it is likely a fresh stock 460 or the static CR has been bumped up a little. Like was said before you can't tell for sure, especially if the cam has been changed but that would be my guess. It is almost certainly not 10:1 or more though. That would likely give you around 160 or so cranking compression, again, depending on the cam.
BTW, cranking 110 or so compression tells me it is likely a fresh stock 460 or the static CR has been bumped up a little. Like was said before you can't tell for sure, especially if the cam has been changed but that would be my guess. It is almost certainly not 10:1 or more though. That would likely give you around 160 or so cranking compression, again, depending on the cam.
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Freshman User
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I was able to remove the rockers on #1 and use a dial on the pushrod. I kept the geometry as in line as I could. My readings were .235 intake and .255 exhaust. My book says the stock lifts are .253 & .278 so I think I'll just go with a cam kit. Thanks for the help guys. It's kind of a pain to reverse engineer a motor you know very little about but I figure it will help with my future build plans.
