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Discussion Starter · #1 ·
Does any have a clue as to what Compression Ratio 041 cast heads 2.2 intake .65 exh 510 lift 242 duration cam on a sbc 400 60 over bore
Forged Flat tops with Valve insets?Just Curious cant keep a Stock Crank in it?:smash:
 

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Discussion Starter · #3 ·
thanks was just curious went to a 355 4140 steel crank stage 2 i rods and je forged pistons much better but i miss the Torque ill tear down the 400 this winter and she why it wont stay toghther!...thanks 4 the input!
 

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depending on the head gasket, deck height and amount of milling the heads have recieved you could be at:

64cc.... 0.041 HG> 11.9

60cc.... 0.015 HG> 13.5

both at zero deck height
 

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Discussion Starter · #5 ·
Nxs Deck Clearance was @0 stock felpros so i think the 13:1 is more in line but would that cause a problem with a stock crank?when it comes to dollars i learn fast...thanks 4 the help!
 

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I have seen more than one stock 400 crank warp. The balancers have a tendency to spin at high speed and throw the balance off.

You have such high compression I would not be suprised if spark knock was trying to spin bearings ....gas, you mentioned race gas, what octane? did you ever drive it with pump gas?
 

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Discussion Starter · #7 ·
Yes Pump gas was a no no Detonation was awful...went to a110 lowlead cured that...but after two engines i gave up first one i pulled down all mains were past the babbit...just wondered if the Compression was too much 4 a stock crank?

Bye the way only Drove it a few miles with Pump gas!
 

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The mains and not the rods?

Doesn't sound like excessive compression, more like a warped crank or... the block is out of align. Replace the caps and feel around the inside perimeter where the bearing resides. If you feel a notch where the cap and block meet either the caps have been installed on the wrong mains or the block is warped.
 

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Discussion Starter · #9 ·
went through all that actually felt a notch on first block and had it line bored still it ate the mains Rods were not Noticeably Damaged ? would like to redoo the 400 would u sugest a new crank? id like to Know what caused it so when i tear it down this winter im going Bearing to Bearing!but the warp is a thought!Just wondering if the external balancer could have been off enough to eat it up?
 

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You need to have the crank checked for runout and the block rechecked on the main alignment. Is it worse on the center mains? If so, I would definately say something is not straight. I actually juste went through a main bearing failure, and mine was due to the machine shop not properly cleaning and brushing the oil passages. I specifically ask for that, but they did not do it. The next shop I took it do did, and they found rust and dirt in oil passages.

Just a thought,

Chris
 
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