I have a motor that I am interested to see if its DC is too high I have a feeling that it might be. here are its specs

383
4.03 bore
3.75 stroke
5.7 in rods
flat top pistons -5cc valve refliefs
54cc heads
cam: 230/236 112 LSA 107 center .544/.554
.039 head gasket
dont know piston to deck or quench

 

here is a pretty cool site you will learn alot from
plus you can download a killer calculator
http://www.empirenet.com/pkelley2/DynamicCR.html

 

To calculate the DCR, you need the intake ATDC max lift timing. To calculate both the static and dynamic CR's you need the deck height and the gasket bore. Do you have access to the machine shop that prepped the block? They should have all the block info you need. The ATDC intake data is in the cam spec card.

 

its Zero deck hieght and the gasket bore is 4.04

 

Yea I've already been there and downloaded the calc i must be filling out one of the fields incorrectly as I got a 11:1 DCR

 

Notice the post by Tito, he's dead on. You have to have the atdc number and 11.1 is to high for DC.

 

You need "advertised" duration, not duration at 0.050" to calculate DCR.

Rich

 

the ATDC spec is 26

 

advertised is 282/288

 

anyone...

 

I calculate your intake closing point as 68 degress ABDC. Your DCR is 9.86. Your SCR is 12.67. I think you are going too far for pump gas. You need a thicker gasket or a bigger cam to bleed off some cylinder pressure. A bigger cam will help with detonation at low enegine speed, but you still may have a problem at or around peak torque.

Rich

 

Correction: intake ABDC max lift timing.

 

alright heres what i got down the list and the only thing im not sure of is the piston to deck clearance
bore 4.03
stroke 3.75
rods 5.75
cc chamber 54
head gasket .039
gasket bor 4.04
flat top pistons -5 cc relief
Cam:
282/288
lsa 112 center 106
IVO (BTDC) 35
evo(BBDC) 82
IVC(ABDC) 67
EVC (ATDC) 26

I keep getting reall high numbers

 

With the above numbers and zero deck piston height I get 12.38 Static CR and 9.72 DCR.

 

I posted the correct numbers. They are too high for pump gas.

Rich