505 BBC Cam vs Compression ratio
Posted: Mon Jun 29, 2020 12:20 am
I currently have a 505 BBC with the following:
13:1 CR
Dart Pro1 325's
Intake Valve: 2.300 Exhaust Valve: 1.900
Lift Int. Exh
.100 85.2 71.9
.200 153.1 120.0
.300 218.0 172.5
.400 286.2 215.9
.500 338.7 247.8
.600 386.7 296.4
.700 388.1 309.6
Cam is as follows
Numbers are based on a 1.7 rocker ratio (the engine has a 1.8 intake rocker on it)
Int. Exh.
Lift .707 .707
Adv. 294 302
.050 265 273
110 lobe sep.
106 Int cent.
.016 lash
@ .050 lift
IVO: 26.5 BTDC
ICL: 58.5 ABDC
EVO: 70.5 BBDC
ECL: 22.5 ATDC
I am putting together a pro touring car, and happened to have this engine laying around. What I'd like to do is see what I can do to make it pump gas friendly while spending as little as possible on it (switching to an LS down the line). If I were to knock the CR down to 10.5:1 or 11:1, would it make it a total dog, or am I going to need to do a cam change as well? It will be going in front of a close ratio T56 and a 3.70 rear gear FWIW. I'm not necessarily trying to optimize this combo, but just trying to make it something I can have fun with until I go to an LS.
13:1 CR
Dart Pro1 325's
Intake Valve: 2.300 Exhaust Valve: 1.900
Lift Int. Exh
.100 85.2 71.9
.200 153.1 120.0
.300 218.0 172.5
.400 286.2 215.9
.500 338.7 247.8
.600 386.7 296.4
.700 388.1 309.6
Cam is as follows
Numbers are based on a 1.7 rocker ratio (the engine has a 1.8 intake rocker on it)
Int. Exh.
Lift .707 .707
Adv. 294 302
.050 265 273
110 lobe sep.
106 Int cent.
.016 lash
@ .050 lift
IVO: 26.5 BTDC
ICL: 58.5 ABDC
EVO: 70.5 BBDC
ECL: 22.5 ATDC
I am putting together a pro touring car, and happened to have this engine laying around. What I'd like to do is see what I can do to make it pump gas friendly while spending as little as possible on it (switching to an LS down the line). If I were to knock the CR down to 10.5:1 or 11:1, would it make it a total dog, or am I going to need to do a cam change as well? It will be going in front of a close ratio T56 and a 3.70 rear gear FWIW. I'm not necessarily trying to optimize this combo, but just trying to make it something I can have fun with until I go to an LS.