Help me set my timing curve please! 236/236 110 cam,
08-01-2008, 08:36 PM
#1
Help me set my timing curve please! 236/236 110 cam, Ok to start off this engine is carbureted with an MSD6010 unit. Which really shouldnt matter as far as timing curves go. I am just looking for what you guys are running with similar camshafts. Here are the cars specs.
1968 Firebird <2900lb
2000 LS1
stock 241 heads
236/236 .651/.651 110+4LSA
Hooker LT headers
Victor JR carb intake
Holley HP750 vacuum secondary carb 72 primaries, 76 secondaries 6.5PV (assume fuel is right as this is a pretty darn close setup)
30 spline T56
4.56 gears with 30" MT ET street radials (roughly 3.73s with a 26" tire)
Anyway Heres what i have. Base timing of 18 degrees going to about 24 degrees by 2000rpm then 28 degrees at 3000rpm. The way the MSD box works is i plot points on a line graph where i want my timing and it follows the line.
Now to tune the MAP vacuum advance there is a separate graph. I plot points on a line graph with the variables being Psia and degrees advance. Right now i have it advancing 10 degrees at 9 psia, and around 5psi i have it advacing around 5 degrees down to 0 degrees at 0.
The car idles at 10.7psia which from best i can converet is around 22hg. This is with the timing idling at about 28 degrees with the vacuum advance. Car idles at 750rpm. At part throttle 3000rpm (not in gear) the car sees about 4.6psia and 31 degrees advance. When i advanced it to 34 degrees i could almost hear it slightly missing or breaking up but it does have open headers right now so its hard to tell it could just be really loud.
I'm really new to tuninng LS1s and really anything without a distributor but this is so much simpler. I just dont know much about what timing i should be running with this engine. Any help please? Thanks guys!
1968 Firebird <2900lb
2000 LS1
stock 241 heads
236/236 .651/.651 110+4LSA
Hooker LT headers
Victor JR carb intake
Holley HP750 vacuum secondary carb 72 primaries, 76 secondaries 6.5PV (assume fuel is right as this is a pretty darn close setup)
30 spline T56
4.56 gears with 30" MT ET street radials (roughly 3.73s with a 26" tire)
Anyway Heres what i have. Base timing of 18 degrees going to about 24 degrees by 2000rpm then 28 degrees at 3000rpm. The way the MSD box works is i plot points on a line graph where i want my timing and it follows the line.
Now to tune the MAP vacuum advance there is a separate graph. I plot points on a line graph with the variables being Psia and degrees advance. Right now i have it advancing 10 degrees at 9 psia, and around 5psi i have it advacing around 5 degrees down to 0 degrees at 0.
The car idles at 10.7psia which from best i can converet is around 22hg. This is with the timing idling at about 28 degrees with the vacuum advance. Car idles at 750rpm. At part throttle 3000rpm (not in gear) the car sees about 4.6psia and 31 degrees advance. When i advanced it to 34 degrees i could almost hear it slightly missing or breaking up but it does have open headers right now so its hard to tell it could just be really loud.
I'm really new to tuninng LS1s and really anything without a distributor but this is so much simpler. I just dont know much about what timing i should be running with this engine. Any help please? Thanks guys!
