Ign timing curve
08-27-2013, 02:26 AM
#1
Registered
Thread Starter
Join Date: Sep 2011
Location: Chesterfield Va.
Posts: 58
Likes: 0
Received 0 Likes
on
0 Posts
Ign timing curve
I know this is a loaded question, but I am looking for opinions for the advance curve GM HEI Marine dist.. in a 468 BBC. It's not a go fast boat 38 ft. 15000 lbs. 468 round port 781 castings with a little bowl work and port matching , dual plane intake 10-1 compression hyd roller motor. I'm looking for big torque not really the HP . I'm thinking the advance should start around 850 900 rpms and be all in by 2800 with a max rpm on these engines around 5500 with a total around 32 to 34 degrees. Tell me what you think ideas etc. I realize it will take some tuning but looking for a good starting point. 
Thanks Jamie
Thanks Jamie
Platinum Member
08-27-2013, 07:00 AM
#3
Registered
with that much compression and iron heads, without 93 don't think you can run that much timing...total about 28-30 max, what would be great if you could run 34-36 up to about 3000 then pull back to 28-30...
08-28-2013, 02:07 AM
#4
Charter Member # 55
Charter Member
I would go with about 20* of advance starting at 1000rpms and all in at 3000rpms. Set total to 32-34*. That is the same an HP500 curve.
BTW, 10:1 compression is way too high, especially for a very heavy boat like yours. It has very high risk of detonating even with 93 octane fuel.
BTW, 10:1 compression is way too high, especially for a very heavy boat like yours. It has very high risk of detonating even with 93 octane fuel.
