type gas
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 82
From: NorCal
Go low buck 87 octane.
Octane is the measure of a fuel's resistivity to pre-ignition. If you're running 10:1 compression or higher, then the engine should run at least 89 octane if not 92 or higher. That way, it won't pre-ignite and lead to "detonation" aka "knock" which can lead to engine damage.
Octane is the measure of a fuel's resistivity to pre-ignition. If you're running 10:1 compression or higher, then the engine should run at least 89 octane if not 92 or higher. That way, it won't pre-ignite and lead to "detonation" aka "knock" which can lead to engine damage.
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
rcraft, Welcome to FTE & the Bumpside Forum 
I buy the cheepest gas on the corner, and don't worry about the other. I am not driving the truck a lot not, but have around 50,000 on the rebuild. It is still strong as a bull.
John
I buy the cheepest gas on the corner, and don't worry about the other. I am not driving the truck a lot not, but have around 50,000 on the rebuild. It is still strong as a bull.
John
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
Also the use of higher octanes are needed while towing or hauling. Then depending on where you live your and loads you carry don't even think or cheap low octane. You may have to even back off on the timing so it don't ping.
Any heavy Towing will add to the death of your exh. seats even with a lead additive only helps about 35% from ping and or over heating the seats to the point on down hill from their.
A good indication that your seats are starting to go is popping back through the carb when going up a hill and you start putting foot into the gas pedal. Will become a lost of power until you let your foot off the gas...
PS
Recommended list of fuel octane for use listed is in the hand book manual the comes in the glove box when new buying a new truck..
orich
Any heavy Towing will add to the death of your exh. seats even with a lead additive only helps about 35% from ping and or over heating the seats to the point on down hill from their.
A good indication that your seats are starting to go is popping back through the carb when going up a hill and you start putting foot into the gas pedal. Will become a lost of power until you let your foot off the gas...
PS
Recommended list of fuel octane for use listed is in the hand book manual the comes in the glove box when new buying a new truck..
orich
Postmaster
Joined: Nov 2012
Posts: 2,806
Likes: 8
From: Langley, BC
I've never before heard anyone say that you need higher octane for towing. I and everyone else use 87 if the engine calls for 87. I towed 12,000lb last summer running 87 in my Highboy up and down a canyon road and it did just fine.
Super Moderator
Joined: Apr 2004
Posts: 34,491
Likes: 2,806
As OEM your '71 pickup 390 used 410 spec pistons, resulting in low 8s compression and a piston about .100 down the hole.
If you have advanced the timing, you may have to use a higher grade of fuel, but at the stock setting, it will be happy with 87.
As per the above, the valve seats will be unhappy regardless.
We had a '66 wagon that burned a valve a 41000 miles. YMMV with valve seat and valve life.
If you have advanced the timing, you may have to use a higher grade of fuel, but at the stock setting, it will be happy with 87.
As per the above, the valve seats will be unhappy regardless.
We had a '66 wagon that burned a valve a 41000 miles. YMMV with valve seat and valve life.
Trending Topics
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
We never stop learning always something new ever day:
Back when these trucks engines were built to run on 91 octane was the lowest rating to use. Higher grade octane maybe needed if you are using a higher advanced timing or having a vacuum advance leak causing a lean condition. Or in a very dry climate like a desert of temps in the 100-126 high day time temps. You never know what temps you'll encounter when your out of town or moving. It can happen to you!
Low grade octane gas burns hotter then higher octanes, this add to detonation/pre-ignition conditions. This is when carbon deposits in the cylinder that becomes red hot like cinders that act as a glow plug and ignite that will or can burn a hole through the piston when the condition is not corrected. Or engine runs on after key is turned off.
An engine that has been running too low of octane the Spark plugs will have a bunch of little type of BB's fused to the center porcelain electro.. This is molten metal off the top of the pistons.
orich
Back when these trucks engines were built to run on 91 octane was the lowest rating to use. Higher grade octane maybe needed if you are using a higher advanced timing or having a vacuum advance leak causing a lean condition. Or in a very dry climate like a desert of temps in the 100-126 high day time temps. You never know what temps you'll encounter when your out of town or moving. It can happen to you!
Low grade octane gas burns hotter then higher octanes, this add to detonation/pre-ignition conditions. This is when carbon deposits in the cylinder that becomes red hot like cinders that act as a glow plug and ignite that will or can burn a hole through the piston when the condition is not corrected. Or engine runs on after key is turned off.
An engine that has been running too low of octane the Spark plugs will have a bunch of little type of BB's fused to the center porcelain electro.. This is molten metal off the top of the pistons.
orich
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
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
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
Hotshot
Joined: Mar 2013
Posts: 14,255
Likes: 199
From: Phoenix, Az.
Kind of a loaded question. I say that because it would kinda depend on the quality of your local gas. Example, here in Phoenix we get crappy gas. Especially if some one buys the Fry's grocery store,Costco, or Sam's club,etc. Lord only knows what it is ...gas. I would suggest you buy Name Brand gas at 87 octane. 2X above on the higher grade for towing. Why risk a motor when a full fill up will only cost about $2.00 more? As expensive as gas is now-a-days I would'nt even miss that $2.00. Also CHEAP insurance.
Thread
Thread Starter
Forum
Replies
Last Post
big block power
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
3
Jul 12, 2002 12:34 AM