So, running 10.15:1 compression ratio in my 390. At the time of engine build, plan was that truck would never go below 3000' elevation (I live at 5300') and didn't plan to tow anything beyond a utility trailer and run regular gas normally. Well like everything else, things change and now tow a 4000lb trailer and have plans to go to well below the 3000' level. I've been down to about 1000' already and with super gas it runs great except that it does ping when pulling up hill. No bueno. I feel pulling timing back may not be enough and have thought about adding an egr setup to help keep cylinder temps down and prevent detonation. I know I've removed a bunch of EGRs over the years so the though of adding one goes against what this old schooler knows, but they do have their purpose. I know will lose a bit of power but considering that engine rated at 360hp, 460lb/ft tq I'm not too concerned. Also considering that at my elevation am already losing about 15% power, so should still be a net gain at 0', plus could block off when not towing. Perhaps the best of both worlds.
Thoughts?

 

Hi,

I would start by re-adjusting the timing before going the EGR route.

 

See:
https://www.ford-trucks.com/forums/1...l#post20769650

 

Get colder heat range spark plugs and back the timing off. You should easily be able to pull enough timing to get rid of any pre-ignition/detonation on 91 octane at your compression ratio.

What RPM range does it ping at? If it doesn't ping at idle, but does at mid range, you need to re curve the distributor so it doesn't advance so quickly.

I would also look at running a Duraspark or GM HEI ignition system and set it up with a module that can pull timing out with the flip of a switch.

 

I'd say go for it. Detonation is no good. Use a thermal vacuum switch and ported carb vac.

 

Just brainstorming here:
EGR cuts out as soon as you give it more than just a little gas, so that may not help much.
All notes above sound true. Retard a little, use slightly heavier springs in distributor, and readjust your vacuum canister for less advance at light throttle.
Might run gas with a little more alcohol in it, or add just a little bit of e85 to tank. Ups the 'octane' but has a little less power.
Note that alcohol burns just a hair quicker, but without enlarging the jets, you get a little less cylinder pressure.
For towing, you are going to need to back off on the timing a little anyway. Not for the rockies, but down on the plains.
Heading for the southeast hills, that thought about a Duraspark setup is a way to go. However, using the 2-degree retard wire only changes it a little.
You may want more than that at times, thus the recurve advice is valid no mater what.

My fantasy is that someone with a background in sound ping analysis would help us get a ping-sensor working on these noisy old FEs. If we can hear it, a system should be able to warn us with a light or something. I hear it is a problem involving ignoring noise from the loose engine design between ignition 'windows'.