Lets see, back off timing (were not talking 10° here just a couple at most, maybe even back off ao the vacuum advance and not retard the mechanical at all) and lose say 1 mpg, say 10 mpg to 9 mpg. Means you now are paying $0.333 a mile instead of $0.300 per mile, if paying $3.00 a gallon . Ok, now spend another 30 cents a gallon for gas or $3.30. If you are lucky and don't loose any mpgs, you get.............gee $0.333 per mile driven. I see no improvement in savings and on top of that if you are running your timing that close to the edge it isn't wise or cost effective if it breaks or melts something it's gonna be way expensive and then there is the down time.

FYI additives sound nice but none, I repeat none have been shown by independent testing to do what they claim, so don't bother. Besides more expensive gas or additives are a bandaid, timing change is a fix and the proper way to solve this guys issue.

 

Jim Henderson's suggestion of carrying higher octane in one tank, reg in the other might be the best solution. Certainly burning high octane for the whole trip is not going to be a savings, dollar-wise. So run on the regular unless the temp gauge goes above normal then switch to the higher octane tank. If all is well with the engine it won't ping if the temp is normal.

I had an experience in Mexico that was a dramatic demonstration of the effect of octane and engine heat/pinging. Climbing out of a deep canyon on a dirt/rock road in 114 degree heat on Pemex regular. (Non efi) Under most circumstances my truck ran well enough on the Pemex. The road was all first and second gear and the truck started first to get hot then pinging set in. I stopped several times and ran the engine at 2,000 rpm to cool it down, but with load it would go back to the same cycle. I was carrying a fiver of U.S. Shell premium which I dumped into the tank which was probably down to three gallons or so, and again ran at high idle till the temp was normal and proceeded to climb again. After that, I was able to drive normally. No pinging, no overheating. Without that premium gasoline, I think that truck would still be in that canyon because the road got even steeper. (Side note, that was when Mexican gasoline was really poor. Now it is essentially the same as what we get in the States.)

 

First thing here, the carbon buildup needed to raise a point of compression is so far above what will build up on a piston as to the point you have a lot more serious trouble than knock, or detonation. Don't believe me, check your compression calculator it takes 20cc of volume to raise a 460 1 point of compression, the usual dish on a 460 piston is 22cc, I have yet to find one totally filled up, infact I would venture a guess you could take the carbon from all 8 cylinders on a dirty engine and not develop 20cc of carbon. On top of that by the time an engine has enough carbon buildup to be an issue, it will usually have cyl wall taper, and blow by that effectively reduces your dynamic compression. Now add to that fact that a late model 460 is lucky if it has 8:1 compression, and heck it should run on 85 octane at sea level. So to clear up why a older engine with carbon buildup will detonate or ping or whatever you want to call it, it has nothing to do at all with raise in compression it has to do with hot spots the preignite the gas before the spark plug fires (which is why it's called predetonation btw) carbon will get extremely hot and stay that way creating hot spots that cause this, so will a sharp edge on a piston, or running too hot of a heat range spark plug. Also yes I have heard of using walnut shells to clean pistons and combustion chambers out when an engine is disasesemble, but there is a much easier, cheaper, and faster way to clean a engine that is running. Start it bring rpms up to about 2000rpm, and mist water down the intake, it will clean almost all the carbon out of the combustion chamber, I have done it on engines I was getting ready to tear down, and the piston tops looked brand new when done.
Also the saying that the engine backing the timing off 1 or 2 degs hurts power and economy is just wrong, yes it will maybe drop 5-10hp, but running too high of octane will drop that much too, and it will do it all the time instead of just when it's pulling hard.
Also since it was brought up, did the 460s ever actually have a knock sensor, I don't recall one on any I have worked on, not all fuel injected engines do have them it was mainly a GM technic to run more compression to get hp numbers up to stay competitive.

 

The study I read that raised the compression ratio a point from deposits was done some years ago in Volkswagons. Maybe a small amount in one engine may have a greater effect in that engine than an equalvalent amount in other engines. Carbon is an offender for hot spots but what is worse is metals that contaminate the combustion chamber principally Calcium and Magnesium. These come from the detergent oils we use in cars and is the reason aircraft use dispersant oils or what they call "ashless" oil. Ford has been using knock sensors since 1980 and continues to use them today but I think your right, the 460's dont have em that I know of. Might be that the base timing is fixed.

 

Gentlemen,

I initiated this post to try to get a simple "yeah" or "nay" to a fairly simple issue I questioned; and it appears I inadvertently may have started an FTE civil war.

I have come up with my own answer/solution to the original question. I started with the keyring the ignition key was attached to and replaced the key with one that starts a 2001 F250 4x4 Crew Cab with a 7.3 Powerstroke Diesel. Now it knocks all the time and I don't have to worry about it. I also don't have to worry about any of the other multitudes of mechanical miscues/malfunctions/and failures that had come to characterize everyday life with my 171,000 mile 97 F350, which has now gone the way of the dinosaur. I came to the conclusion that I, like Popeye, "...Can stands what I can stands and then I can stands no more!"

I appreciate all of your input, regret some of the blows inflicted, yet admire the passion of all who have "contributed" to this thread.

sa_rains

 

Well SA, glad you took care of your question yourself.

But this was a very good thread in my eyes. Things do get a little heated here sometimes but that is not to be taken seriously. You get a lot of smart and experienced guys airing a lot of views and the net result is that when you boil it all down, it is very instructive. We all live in our own vacuum and nobody thinks of everything so having these discussions are mentally stimulating. I often come away saying to myself 'gotta remember that.' Like the 460 knock sensor... didn't know that.

 

Congrats on your Stroke SA. There's plenty of passion in the Stroke forum too.

 

sa, don't worry about it, these little "aurguments" get lots of info out. Well now that you have a PSD, the next step is to get you infected with PMS (powerstroke modification syndrome) it will start small like the kwik filter, and ccv mod and progress from thier. I have a 2000 with a 7.3 and love it, and I think you are really gonna like that one.

 

Howdy y'all,


I have a 460 in my boat (rated at 340hp)

OMC says to set the timing at 10 degrees BTDC with 86 octane and 15 degrees with 92 or better.
(advance curve takes it to about 35 degrees max)

My bigblock race buddy told me to set the timing at what ever makes it ping and back it off 2 degrees at a time until it doesn't.


I'm at 14 degrees with Arco regular(10% booze) and it's not pinging yet.

no octane booster, secret sauce etc.

I think running a 460 in a boat is probably the hardest thing you can do to it....



Regards,

Rick

 

Listening to your buddy and doing street stuff to your boat motor is gonna it burn down. You realize boat that a boat engine is working hard all the time, like going over a steep mountain pass that never ends. I was a certified OMC and Merc mechanic for a lot of years and you don't want to do that in a boat motor. On the street is ok, but a boat is a different world.

 

This is of course is why I did not take it past 14 degrees. (btw this particular race buddy has been building big block marine engines since the 70's)


(do you shoot blackpowder in that 45/70?)

 

Yes, I do shoot blackpowder in one of my 45/70s. That would be an original Model 1873 "Trapdoor", well over 100 years old and still shots great. In my Marlin 1895SS, Ruger #1, Mauser 1871/84 custom and Thompson Contender Super 14 pistol I shoot smokeless as I actually hunt with them.

 

Oh MAN....this is off topc!!......Moderator PLEASE forgive me!


I have an 1873 Carbine (Dad bought for 7$ when he was a kid in the 30's, ) in pristine condition that I shoot FF in .........+ a 45-120 Pedersoli Sharps that I shoot F in!

Very cool stuff...

 

Yeah and to prevent that I sent you a PM.

 

I have an 86 F-250 4x4 460 C-6 3:55 gears and I pull a 10,000# travel trailer and I have tried it all and 85 octane gives me the same as 91 octane. The only time 91 octane might of helped was when I pull from Kingman AZ to Las Vegas. I get pinging when I cross the river and start up the other side until I get to about 2,000 FT ELEV. I run 10 advanced overall 36 degrees. In fact I filled in Las Vegas and headed up the eastern side of Nevada and the higher I got the better mileage I got on 85 octane.