I have a 93 f150 4.9 and the motor doesnt seem to have its full potential. I tried seafoam in the gas vac line and oil. I noticed little to know difference. Motor had 177k on it. I heard ppl talk about putting a pint of diesel to a full tank of gas can do wonders. Can anyone shed light on that.

 

I've heard this and would advise against it, as little as %1 diesel can do some damage. The other way around (gas in a diesel tank) works like a charm to help burn out carbon deposits. Diesel has a higher flash point than gasoline and won't ignite in a gasser, it may lube valves or rings or something along that nature but they make products for that and even those don't really work that great. If putting a little diesel in your tank really accomplished anything everyone and their mother would be putting a couple ounces in every time they fill up.

Check engine vac, you can learn a lot from a vac reading, plenty of videos on youtube that discuss the 8 things it can tell you.

Ensure fuel pressure and good ignition system.

 

You might want to up your timing a little. I'm running mine at about 16 degrees. At the standard 10 it ran like a slug. It will kill some mpg though.

 

Kill MPG? WRONG! I've yet to have seen a single timing bump report hurting mpg. Gaining, yes, hurting, nope! Running 15 degrees on mine for more than a year and along with all of the other mods, I'm still at 21mpg.

The easiest and cheapest way to wake up the 300 is to do the electric fan swap. Dual factory fans cans be had for less than $30 at the salvage yard and the fan controller for $18 at Advanced Auto. You can purchase brand new factory style Chrysler or Ford dual electric fans for around $100 as well all day long. They are much better IMO than aftermarket single fans. Lot's of good reading here.
https://www.f150forum.com/f10/electr...light=fan+swap

You can expect a real power gain of around 15hp swapping to the e fans. A thorough tune up and doing the seafoam through the brake booster method will clean the top end. Again, never heard of Seafoaming the top end not having positive results. Running it in the gas is a maintenance item. Flushing the top end is the way to go. As far as running diesel mixtures, I have not, but I see it done first hand allot. My boss runs a gallon to his full tank in his Escalade about once a month and says that it keeps the motor clean. He's an engine builder and a classic car restorer and knows his stuff. Likewise, once in a while, he will run a gallon of gas through the 6.0's and 7.3 ambulances just because with no ill effects.

Personally, i did run two cycle in my 300 for a couple of years to lubricate the top end. It immediately ran quieter and never had an issue. I added about a 1/4 of a quart to every full tank, 16-17 gallons, and there was a noticeable difference as far as the clatter the 300 once had. After I went through the major tune up and flushed the motor, it ran super quiet without the two cycle and I got out of the habit.

 

since your talking gasoline additives here's a dyno result of gas and octane additives.
just so you know for sure if they actually help. i'll find the link to the article they messed with the timing but these results were stock timing on a FI Hemi. (for anyone that doesn't know Ford and GM made lots of Hemi's but can't use the copyrighted name)

87-Octane Unleaded: 396.0 hp/401.3 lb-ft

87-Octane Unleaded With 104+ Octane Booster: 397.9 hp/403.1 lb-ft

91-Octane Unleaded: 402.1 hp/409.4 lb-ft

91-Octane Unleaded With 104+ Octane Booster: 399.8 hp/403.6 lb-ft

100-Octane Unleaded: 403.5 hp/407.5 lb-ft

114-Octane Leaded: 408.3 hp/414.7 lb-ft


http://www.hotrod.com/techarticles/e...ng_comparison/

 

OK, maybe killing is the wrong word. When you turn the timing up, the engine idles higher, thus using a little more gas to maintain higher speed. Now if your driving highway or open road, it won't effect it much if at all. But if our doing city driving, the higher idle at each stop or stalled traffic will eat at your gas. And that's not from a report, just real life.

 

You do know idle can be adjusted to compensate for that right?

 

I thought the truck would adjust idle on its own after a timing bump?

 

Try a qt of ATF in a full tank to burn off carbon. This does work.

 

Techron, Gumout Regane, Gumout Regane High Mileage, Redline SL-1 or BG44K. All of these have PEA in it and will do wonders.

I hear that the Royal Purple fuel system treatment is good too.

Marvel mystery oil can help if you have the patience to measure the proper amount for each tank.