bumped timing on my Mefi 3 to 36.5 degrees WOT from 29.5 using 89 octane and gained solid 3mph on boat.
Eddie Marine std type alum manifolds gave a couple more mph.
Also using K&N air filters but they have always been on the boat so dont know the difference.

Stock cam? Id be very nervous going that high on 100 map timing for a stock 502mpi because cam is so small and may cause detonation. Did you drive it with something like scanner pro and watch for KR?

Can you pull 502 BBC crank w/o removing heads

Based upon this thread, I'm guessing not.....I had same thoughts!

Nervous going that high with 89 octane I meant, would want to see the KR even with 93

Another MPI project worth mentioning I did this summer: .030 over 502 (509) (I did NOT build the motor), a chopped down runner, chopped down divider 502 mpi intake (I did), port matched, well blended, TPIS twin 68mm TB, early FA, promax chingchong heads assembled by Jimmy V, made 600 ish on dyno w open dyno headers, 560 ish wiith EMIs ,was installed in a 2000 28 powerquest then I tuned it on the water. Ran 81 Mph at LOTO at the shootout turning a 28 pitch.
Second 509 I built w AFR 300 Oval ports, Edelbrock Proflow mini tunnel ram that we ported with a worked 90 MM TB, made 695 hp at 6300 on my dyno in dry, open header trim, high 650s at 5800/5900 with EMIs with long, dry to tip tails. Hasnt ran a good number in the boat yet because boat is a Orca the killer whale PIG (29 foot Envison).Smitty

What camshafts were in these motors?

articfriends
On the knock retard, i checked about 3 years ago when i bumped up the timing and had no retard, but that was on premium gas, which I've used my whole life even on stock motors.

Recently I sometimes put in 89, and I haven't checked it live for knock lately, but have looked at the alarms history on the diagnostic program and don't recall seeing any history of KR logged. But from what i see with all of ya'lls info, it's a little too close and I will go back to premium.

Motor just feels too good at 36 WOT vs stock 29, to drop it back down. Stock even drops down to around low low 20's when cruising and open it up. I bumped that up to around low 30's at RPM above 3000 and WOT. A noticeable difference. I've got the charts somewhere.

the 509 with Edelbrock manifold had a hyd roller, 113.5 ls, 236/[email protected], .650 lift double fire swap
the mpi 509 w ching chong heads had a cam from Jimmy V , hyd roller, std firing order, 236/244 @.050, .646 lift

If your not getting KR on the 89, keep running it, I havent pushed the limits much on a 502 mag with bone stock can because most motors I tune have bigger cam. The few I have tuned w stock cam (gimme fuels 38 ft) I kept a little more conservative because he may be able to hold it at wot forever, another one had twin hot air superchargers and went into KR with stock timing on 93, Smitty

Bumping this old thread (sorry), looking for help building a high HP 540 MPI engine for a Baja Outlaw 25, which will eventually be Pro Charged, honestly looking to duplicate the LPE 540 marine package JL used to produce (585 HP), then strap the blower on it.