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SCR vs. DCR
https://slantsix.org/forum/viewtopic.php?t=45431
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Author:  805moparkid [ Sun Jun 26, 2011 6:20 pm ]
Post subject:  SCR vs. DCR

ok so this is a new variable that i have come across... i know that a big cam bleeds off compression and what not so i started looking...

and well im not sure i like what i found...

here are the specs on my motor (street/strip 91 octane)
3.480 bore
4.120 stroke
6.700 rod
.157 in the hole
3.510 bore head gasket .020 compresses
44cc chambers
cam's IVC is 67 (adv) and 51 ( @ .050)
cam is .475 valve lift 246 @ .050 106LSA installed @ 102

now the program i use to figure compression and what not says i have 9.96:1 SCR... good... i just went onto wallace and it said its 235.12ci and a 8.95 compression! based on this my DCR is like 7.6!

now i need to be a little closer to 8.5 to 9 DCR...

am i just missing a step or what? thanks guys...

Author:  DusterIdiot [ Sun Jun 26, 2011 7:46 pm ]
Post subject:  Nope that's right...

Double checked your numbers, they're right...If I were picking a cam with a 246 dur @ .050 I'd be shooting for the 10-11:SCR range and hoping for something in the 8.6:DCR range...

I usually deck the block pretty well, then fine tune the CR by shaving the head after I have checked the piston to deck height...Sounds like you need to deck the head a bit more to make it all jake...

Good Luck,

-D.idiot

Author:  805moparkid [ Sun Jun 26, 2011 11:04 pm ]
Post subject:  Re: Nope that's right...

Quote:
Double checked your numbers, they're right...If I were picking a cam with a 246 dur @ .050 I'd be shooting for the 10-11:SCR range and hoping for something in the 8.6:DCR range...

I usually deck the block pretty well, then fine tune the CR by shaving the head after I have checked the piston to deck height...Sounds like you need to deck the head a bit more to make it all jake...

Good Luck,

-D.idiot
yea the head has .110 off and the block is .030 off (.157 in the hole) this was my first motor build so i would next tike start with the block and then the head...

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