93 Octane necessary??
Thread Starter
|
5th Wheeling
Joined: Jan 2019
Posts: 41
Likes: 0
93 Octane necessary??
I was told on a 70's engine, it needs 93 octane. Then I did some research, and found that too high octane causes rough idling and other problems.
I thought regular gas was fine, and even preferred. Any thoughts??
Here is engine description (77 F250) where Im told it runs on 93 octane :
351 modified engine ,about 50,000 miles on it. Built at a race shop in Florida. Edelbrock performer 650 CFM 4 barrel carb and intake, Edelbrock high flow water pump, Four core radiator, MSD ignition. Headman long tube headers, Flowmaster mufflers. C6 trans, 205 transfer case Dana 60 in rear, Dana 44 upfront with Yukon Chrome Molly axle shafts.
I thought regular gas was fine, and even preferred. Any thoughts??
Here is engine description (77 F250) where Im told it runs on 93 octane :
351 modified engine ,about 50,000 miles on it. Built at a race shop in Florida. Edelbrock performer 650 CFM 4 barrel carb and intake, Edelbrock high flow water pump, Four core radiator, MSD ignition. Headman long tube headers, Flowmaster mufflers. C6 trans, 205 transfer case Dana 60 in rear, Dana 44 upfront with Yukon Chrome Molly axle shafts.
Freshman User
Joined: Nov 2016
Posts: 42
Likes: 1
Not knowing the compression I couldn't tell you...but if it was stock you definitely do not need 93. The main reason why 351/400s and 70s 460s are pooches is because they have such low compression. Almost anything from 73-81ish will be lower comp, your friend is off the mark a bit.
Believe Nothing
Joined: Jun 2004
Posts: 7,514
Likes: 398
From: W. Central FL.
I
:
351 modified engine ,about 50,000 miles on it. Built at a race shop in Florida. Edelbrock performer 650 CFM 4 barrel carb and intake, Edelbrock high flow water pump, Four core radiator, MSD ignition. Headman long tube headers, Flowmaster mufflers. C6 trans, 205 transfer case Dana 60 in rear, Dana 44 upfront with Yukon Chrome Molly axle shafts.
:
351 modified engine ,about 50,000 miles on it. Built at a race shop in Florida. Edelbrock performer 650 CFM 4 barrel carb and intake, Edelbrock high flow water pump, Four core radiator, MSD ignition. Headman long tube headers, Flowmaster mufflers. C6 trans, 205 transfer case Dana 60 in rear, Dana 44 upfront with Yukon Chrome Molly axle shafts.
Mountain Pass
Joined: Sep 2017
Posts: 200
Likes: 0
From what I know Edelbrock carbs are not calibrated for or comparable with alcohol, race or E85 pump fuel. They also need a fuel filter between the fuel pump and the carb.
Thread Starter
|
5th Wheeling
Joined: Jan 2019
Posts: 41
Likes: 0
this is what he said:
"It has always run that way it’s an old Engine from the 70s those things were made to run on regular gas 93 octane is the closest thing to that and I have confirmed that with quite a few different mechanics. If you run 87 in it it starts pinging real bad.There are different versions of 351 modified. This engine is a truck version and has a towing package cam in it. This is not a typical 351 that you would find in one of the Broncos or Torino vehicles.That could be the reason it runs only on regular gas or 93 octane. I have never researched that other than opinions from mechanic friends."
Laughing Gas
Joined: Apr 2018
Posts: 1,244
Likes: 12
It was probably built with higher compression than stock. It might only need the higher octane when pulling though.
You could try putting 87 in a bottle pre-fuel pump and see how it runs off that.
You could try putting 87 in a bottle pre-fuel pump and see how it runs off that.
Trending Topics
Grumpy goat
Joined: May 2017
Posts: 3,058
Likes: 594
And I wouldn't trust pump gas ratings. Gas stations get caught scamming customers all the time. We had one nearby that was selling three different octane fuels for over 20 years. Someone (probably fuel delivery driver) busted them out....They only had one fuel tank. I buy Klotz octane boost, 87 octane fuel, and mix it myself so I know what I'm getting.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
Lead Driver
Joined: Oct 2018
Posts: 7,879
Likes: 2,367
If it's stock or anywhere near it and you're pinging then your timing is too advanced. you wouldn't need 93 or anything near it.
There is no downside to more octane besides wasted money. when people talk about higher octane in 70's engines they mean before mid 1971. after that with rare exception 70's engines are dogs and require nothing special. the 351 and 400 were certainly no exception.
There is no downside to more octane besides wasted money. when people talk about higher octane in 70's engines they mean before mid 1971. after that with rare exception 70's engines are dogs and require nothing special. the 351 and 400 were certainly no exception.
Lead Driver
Joined: Oct 2018
Posts: 7,879
Likes: 2,367
91 was the lowest octane you could get back then. if your 360 is stock it's low compression and will run fine regular gas today if you don't want to spend the money on super. worst case you may need to slightly retard the timing. your call.
if your 360 is stock octane is the least of your problem. the lack of lead trashing your valve seats is what will take you out. but if you're not towing it should take a while.
if your 360 is stock octane is the least of your problem. the lack of lead trashing your valve seats is what will take you out. but if you're not towing it should take a while.
Laughing Gas
Joined: Nov 2013
Posts: 1,207
Likes: 60
From: S.E. Louisiana;so far USA
Octane requirement depends on a lot of factors; mostly compression and timing. My '76 460 runs fine on 87 without any distress. But it is almost totally stock. You should determine what your engine needs. You should use the minimum octane that will not produce pre-ignition. Sustained knocking can cause engine damage. If 87 knocks then try the next higher; 89 or whatever is available in your area. If it requires 93 to stop the knocking, then use 93.
