March 24, 2020, 09:11 PM
R.BOLDEN489 BBC TIMING
I purchased a race car with a 489 BBC, I checked the timing and its on 40 degrees. I was just wondering if anyone else runs that much timing. This car ran consistent and done well. The motor has a 2927 intake,1050 dominator with 2"spacer,aluminum pro comp heads that have been worked,dome arp pistons,722/722 lunati roller cam,and I was told they had to move the cam around to get valve to piston clearance and that it had a lot of compression.this is in a 3100# plus car that runs 1/8 mile with a powerglide and 488 gear
March 24, 2020, 09:23 PM
HS professorI run 38-40 degrees on all my big blocks with a big dome on gas. If running alky, 35 degrees seemed to work well. They all start easily and don't detonate on 110 octane, These are 454-468 stuff with off the shelf pistons, so compression is never more than a true 12.0.
March 24, 2020, 09:35 PM
more cubesYep, not uncommon at all. I don’t think many try more timing based on what they’ve heard it needs. I had a 15 to 1, 615 BBC with old conventional heads long ago that ran best at 40* on gas. It picked up like .04 and around 1.5 mph going up from 38* IIRC, running 7.40’s at 180. I didn't expect it to like it.
March 25, 2020, 09:55 AM
FootbrakeJimOP did not mention what fuel it burns, so I assume gas. My 468 with big domes liked 40* best on race gas, not a lot of diff from 38* though, like .01-.02 quicker, maybe 0.5-1 MPH faster, so I went with the safer 38 in case of fuel quality variances, etc.
On methanol, it likes 36* best. Tested at 2* increments, from 32-40.
March 25, 2020, 10:09 AM
TOP38quote:
Originally posted by R.BOLDEN:
I purchased a race car with a 489 BBC, I checked the timing and its on 40 degrees. I was just wondering if anyone else runs that much timing. This car ran consistent and done well. The motor has a 2927 intake,1050 dominator with 2"spacer,aluminum pro comp heads that have been worked,dome arp pistons,722/722 lunati roller cam,and I was told they had to move the cam around to get valve to piston clearance and that it had a lot of compression.this is in a 3100# plus car that runs 1/8 mile with a powerglide and 488 gear
Assuming the pointer is correct for that motor with open chambered heads and a decent domed piston 38 to 42 is common.
March 25, 2020, 10:53 AM
R.BOLDENYes I checked the pointer and it is correct,the previous owner run 110 race gas,and I am going to run Avgas from the airport. I'm shifting it on 6600 and going through no more than that,and it has #8 ngk plugs in it,he had a Autolite 3933 which is like a #9 ngk.i normally run #7 ngk in all my small blocks, but this is my first bbc
March 25, 2020, 12:04 PM
chasracerYou could go to the colder #9 NGK and bump the timing a couple of degrees to see if it likes it.